[clang-tools-extra] 7d2ea6c - [clang-tidy][NFC] Use C++17 nested namespaces in the clang-tidy folder

[Carlos Galvez via cfe-commits]

Author: Carlos Galvez
Date: 2023-01-14T18:51:39Z
New Revision: 7d2ea6c422d3f5712b7253407005e1a465a76946

URL: https://github.com/llvm/llvm-project/commit/7d2ea6c422d3f5712b7253407005e1a465a76946
DIFF: https://github.com/llvm/llvm-project/commit/7d2ea6c422d3f5712b7253407005e1a465a76946.diff

LOG: [clang-tidy][NFC] Use C++17 nested namespaces in the clang-tidy folder

Fix applied by running:

run-clang-tidy.py -checks=-*,modernize-concat-nested-namespaces

Differential Revision: https://reviews.llvm.org/D141770

Added: 
    

Modified: 
    clang-tools-extra/clang-tidy/ClangTidy.cpp
    clang-tools-extra/clang-tidy/ClangTidyCheck.cpp
    clang-tools-extra/clang-tidy/ClangTidyDiagnosticConsumer.cpp
    clang-tools-extra/clang-tidy/ClangTidyModule.cpp
    clang-tools-extra/clang-tidy/ClangTidyOptions.cpp
    clang-tools-extra/clang-tidy/ClangTidyProfiling.cpp
    clang-tools-extra/clang-tidy/ExpandModularHeadersPPCallbacks.cpp
    clang-tools-extra/clang-tidy/GlobList.cpp
    clang-tools-extra/clang-tidy/NoLintDirectiveHandler.cpp
    clang-tools-extra/clang-tidy/abseil/AbseilTidyModule.cpp
    clang-tools-extra/clang-tidy/abseil/CleanupCtadCheck.cpp
    clang-tools-extra/clang-tidy/abseil/DurationAdditionCheck.cpp
    clang-tools-extra/clang-tidy/abseil/DurationComparisonCheck.cpp
    clang-tools-extra/clang-tidy/abseil/DurationConversionCastCheck.cpp
    clang-tools-extra/clang-tidy/abseil/DurationDivisionCheck.cpp
    clang-tools-extra/clang-tidy/abseil/DurationFactoryFloatCheck.cpp
    clang-tools-extra/clang-tidy/abseil/DurationFactoryScaleCheck.cpp
    clang-tools-extra/clang-tidy/abseil/DurationRewriter.cpp
    clang-tools-extra/clang-tidy/abseil/DurationSubtractionCheck.cpp
    clang-tools-extra/clang-tidy/abseil/DurationUnnecessaryConversionCheck.cpp
    clang-tools-extra/clang-tidy/abseil/FasterStrsplitDelimiterCheck.cpp
    clang-tools-extra/clang-tidy/abseil/NoInternalDependenciesCheck.cpp
    clang-tools-extra/clang-tidy/abseil/NoNamespaceCheck.cpp
    clang-tools-extra/clang-tidy/abseil/RedundantStrcatCallsCheck.cpp
    clang-tools-extra/clang-tidy/abseil/StrCatAppendCheck.cpp
    clang-tools-extra/clang-tidy/abseil/StringFindStartswithCheck.cpp
    clang-tools-extra/clang-tidy/abseil/StringFindStrContainsCheck.cpp
    clang-tools-extra/clang-tidy/abseil/TimeComparisonCheck.cpp
    clang-tools-extra/clang-tidy/abseil/TimeSubtractionCheck.cpp
    clang-tools-extra/clang-tidy/abseil/UpgradeDurationConversionsCheck.cpp
    clang-tools-extra/clang-tidy/add_new_check.py
    clang-tools-extra/clang-tidy/altera/AlteraTidyModule.cpp
    clang-tools-extra/clang-tidy/altera/IdDependentBackwardBranchCheck.cpp
    clang-tools-extra/clang-tidy/altera/KernelNameRestrictionCheck.cpp
    clang-tools-extra/clang-tidy/altera/SingleWorkItemBarrierCheck.cpp
    clang-tools-extra/clang-tidy/altera/StructPackAlignCheck.cpp
    clang-tools-extra/clang-tidy/altera/UnrollLoopsCheck.cpp
    clang-tools-extra/clang-tidy/android/AndroidTidyModule.cpp
    clang-tools-extra/clang-tidy/android/CloexecAccept4Check.cpp
    clang-tools-extra/clang-tidy/android/CloexecAcceptCheck.cpp
    clang-tools-extra/clang-tidy/android/CloexecCheck.cpp
    clang-tools-extra/clang-tidy/android/CloexecCreatCheck.cpp
    clang-tools-extra/clang-tidy/android/CloexecDupCheck.cpp
    clang-tools-extra/clang-tidy/android/CloexecEpollCreate1Check.cpp
    clang-tools-extra/clang-tidy/android/CloexecEpollCreateCheck.cpp
    clang-tools-extra/clang-tidy/android/CloexecFopenCheck.cpp
    clang-tools-extra/clang-tidy/android/CloexecInotifyInit1Check.cpp
    clang-tools-extra/clang-tidy/android/CloexecInotifyInitCheck.cpp
    clang-tools-extra/clang-tidy/android/CloexecMemfdCreateCheck.cpp
    clang-tools-extra/clang-tidy/android/CloexecOpenCheck.cpp
    clang-tools-extra/clang-tidy/android/CloexecPipe2Check.cpp
    clang-tools-extra/clang-tidy/android/CloexecPipeCheck.cpp
    clang-tools-extra/clang-tidy/android/CloexecSocketCheck.cpp
    clang-tools-extra/clang-tidy/android/ComparisonInTempFailureRetryCheck.cpp
    clang-tools-extra/clang-tidy/boost/BoostTidyModule.cpp
    clang-tools-extra/clang-tidy/boost/UseToStringCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/ArgumentCommentCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/AssertSideEffectCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/AssignmentInIfConditionCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/BadSignalToKillThreadCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/BoolPointerImplicitConversionCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/BranchCloneCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/BugproneTidyModule.cpp
    clang-tools-extra/clang-tidy/bugprone/CopyConstructorInitCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/DanglingHandleCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/DynamicStaticInitializersCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/EasilySwappableParametersCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/ExceptionEscapeCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/FoldInitTypeCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/ForwardDeclarationNamespaceCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/ForwardingReferenceOverloadCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/ImplicitWideningOfMultiplicationResultCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/InaccurateEraseCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/IncorrectRoundingsCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/InfiniteLoopCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/IntegerDivisionCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/LambdaFunctionNameCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/MacroParenthesesCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/MacroRepeatedSideEffectsCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/MisplacedOperatorInStrlenInAllocCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/MisplacedPointerArithmeticInAllocCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/MisplacedWideningCastCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/MoveForwardingReferenceCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/MultipleStatementMacroCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/NoEscapeCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/NotNullTerminatedResultCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/ParentVirtualCallCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/PosixReturnCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/RedundantBranchConditionCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/ReservedIdentifierCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/SharedPtrArrayMismatchCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/SignalHandlerCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/SignedCharMisuseCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/SizeofContainerCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/SizeofExpressionCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/SmartPtrArrayMismatchCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/SpuriouslyWakeUpFunctionsCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/StandaloneEmptyCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/StringConstructorCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/StringIntegerAssignmentCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/StringLiteralWithEmbeddedNulCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/StringviewNullptrCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/SuspiciousEnumUsageCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/SuspiciousIncludeCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/SuspiciousMemoryComparisonCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/SuspiciousMemsetUsageCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/SuspiciousMissingCommaCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/SuspiciousReallocUsageCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/SuspiciousSemicolonCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/SuspiciousStringCompareCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/SwappedArgumentsCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/TerminatingContinueCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/ThrowKeywordMissingCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/TooSmallLoopVariableCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/UncheckedOptionalAccessCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/UndefinedMemoryManipulationCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/UndelegatedConstructorCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/UnhandledExceptionAtNewCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/UnhandledSelfAssignmentCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/UnusedRaiiCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/UnusedReturnValueCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/UseAfterMoveCheck.cpp
    clang-tools-extra/clang-tidy/bugprone/VirtualNearMissCheck.cpp
    clang-tools-extra/clang-tidy/cert/CERTTidyModule.cpp
    clang-tools-extra/clang-tidy/cert/CommandProcessorCheck.cpp
    clang-tools-extra/clang-tidy/cert/DefaultOperatorNewAlignmentCheck.cpp
    clang-tools-extra/clang-tidy/cert/DontModifyStdNamespaceCheck.cpp
    clang-tools-extra/clang-tidy/cert/FloatLoopCounter.cpp
    clang-tools-extra/clang-tidy/cert/LimitedRandomnessCheck.cpp
    clang-tools-extra/clang-tidy/cert/MutatingCopyCheck.cpp
    clang-tools-extra/clang-tidy/cert/NonTrivialTypesLibcMemoryCallsCheck.cpp
    clang-tools-extra/clang-tidy/cert/PostfixOperatorCheck.cpp
    clang-tools-extra/clang-tidy/cert/ProperlySeededRandomGeneratorCheck.cpp
    clang-tools-extra/clang-tidy/cert/SetLongJmpCheck.cpp
    clang-tools-extra/clang-tidy/cert/StaticObjectExceptionCheck.cpp
    clang-tools-extra/clang-tidy/cert/StrToNumCheck.cpp
    clang-tools-extra/clang-tidy/cert/ThrownExceptionTypeCheck.cpp
    clang-tools-extra/clang-tidy/cert/VariadicFunctionDefCheck.cpp
    clang-tools-extra/clang-tidy/concurrency/ConcurrencyTidyModule.cpp
    clang-tools-extra/clang-tidy/concurrency/MtUnsafeCheck.cpp
    clang-tools-extra/clang-tidy/concurrency/ThreadCanceltypeAsynchronousCheck.cpp
    clang-tools-extra/clang-tidy/cppcoreguidelines/AvoidConstOrRefDataMembersCheck.cpp
    clang-tools-extra/clang-tidy/cppcoreguidelines/AvoidDoWhileCheck.cpp
    clang-tools-extra/clang-tidy/cppcoreguidelines/AvoidGotoCheck.cpp
    clang-tools-extra/clang-tidy/cppcoreguidelines/AvoidNonConstGlobalVariablesCheck.cpp
    clang-tools-extra/clang-tidy/cppcoreguidelines/AvoidReferenceCoroutineParametersCheck.cpp
    clang-tools-extra/clang-tidy/cppcoreguidelines/CppCoreGuidelinesTidyModule.cpp
    clang-tools-extra/clang-tidy/cppcoreguidelines/InitVariablesCheck.cpp
    clang-tools-extra/clang-tidy/cppcoreguidelines/InterfacesGlobalInitCheck.cpp
    clang-tools-extra/clang-tidy/cppcoreguidelines/MacroUsageCheck.cpp
    clang-tools-extra/clang-tidy/cppcoreguidelines/NarrowingConversionsCheck.cpp
    clang-tools-extra/clang-tidy/cppcoreguidelines/NoMallocCheck.cpp
    clang-tools-extra/clang-tidy/cppcoreguidelines/OwningMemoryCheck.cpp
    clang-tools-extra/clang-tidy/cppcoreguidelines/PreferMemberInitializerCheck.cpp
    clang-tools-extra/clang-tidy/cppcoreguidelines/ProBoundsArrayToPointerDecayCheck.cpp
    clang-tools-extra/clang-tidy/cppcoreguidelines/ProBoundsConstantArrayIndexCheck.cpp
    clang-tools-extra/clang-tidy/cppcoreguidelines/ProBoundsPointerArithmeticCheck.cpp
    clang-tools-extra/clang-tidy/cppcoreguidelines/ProTypeConstCastCheck.cpp
    clang-tools-extra/clang-tidy/cppcoreguidelines/ProTypeCstyleCastCheck.cpp
    clang-tools-extra/clang-tidy/cppcoreguidelines/ProTypeMemberInitCheck.cpp
    clang-tools-extra/clang-tidy/cppcoreguidelines/ProTypeReinterpretCastCheck.cpp
    clang-tools-extra/clang-tidy/cppcoreguidelines/ProTypeStaticCastDowncastCheck.cpp
    clang-tools-extra/clang-tidy/cppcoreguidelines/ProTypeUnionAccessCheck.cpp
    clang-tools-extra/clang-tidy/cppcoreguidelines/ProTypeVarargCheck.cpp
    clang-tools-extra/clang-tidy/cppcoreguidelines/SlicingCheck.cpp
    clang-tools-extra/clang-tidy/cppcoreguidelines/SpecialMemberFunctionsCheck.cpp
    clang-tools-extra/clang-tidy/cppcoreguidelines/VirtualClassDestructorCheck.cpp
    clang-tools-extra/clang-tidy/darwin/AvoidSpinlockCheck.cpp
    clang-tools-extra/clang-tidy/darwin/DarwinTidyModule.cpp
    clang-tools-extra/clang-tidy/darwin/DispatchOnceNonstaticCheck.cpp
    clang-tools-extra/clang-tidy/fuchsia/DefaultArgumentsCallsCheck.cpp
    clang-tools-extra/clang-tidy/fuchsia/DefaultArgumentsDeclarationsCheck.cpp
    clang-tools-extra/clang-tidy/fuchsia/FuchsiaTidyModule.cpp
    clang-tools-extra/clang-tidy/fuchsia/MultipleInheritanceCheck.cpp
    clang-tools-extra/clang-tidy/fuchsia/OverloadedOperatorCheck.cpp
    clang-tools-extra/clang-tidy/fuchsia/StaticallyConstructedObjectsCheck.cpp
    clang-tools-extra/clang-tidy/fuchsia/TrailingReturnCheck.cpp
    clang-tools-extra/clang-tidy/fuchsia/VirtualInheritanceCheck.cpp
    clang-tools-extra/clang-tidy/google/AvoidCStyleCastsCheck.cpp
    clang-tools-extra/clang-tidy/google/AvoidNSObjectNewCheck.cpp
    clang-tools-extra/clang-tidy/google/AvoidThrowingObjCExceptionCheck.cpp
    clang-tools-extra/clang-tidy/google/AvoidUnderscoreInGoogletestNameCheck.cpp
    clang-tools-extra/clang-tidy/google/DefaultArgumentsCheck.cpp
    clang-tools-extra/clang-tidy/google/ExplicitConstructorCheck.cpp
    clang-tools-extra/clang-tidy/google/ExplicitMakePairCheck.cpp
    clang-tools-extra/clang-tidy/google/FunctionNamingCheck.cpp
    clang-tools-extra/clang-tidy/google/GlobalNamesInHeadersCheck.cpp
    clang-tools-extra/clang-tidy/google/GlobalVariableDeclarationCheck.cpp
    clang-tools-extra/clang-tidy/google/GoogleTidyModule.cpp
    clang-tools-extra/clang-tidy/google/IntegerTypesCheck.cpp
    clang-tools-extra/clang-tidy/google/OverloadedUnaryAndCheck.cpp
    clang-tools-extra/clang-tidy/google/TodoCommentCheck.cpp
    clang-tools-extra/clang-tidy/google/UnnamedNamespaceInHeaderCheck.cpp
    clang-tools-extra/clang-tidy/google/UpgradeGoogletestCaseCheck.cpp
    clang-tools-extra/clang-tidy/google/UsingNamespaceDirectiveCheck.cpp
    clang-tools-extra/clang-tidy/hicpp/ExceptionBaseclassCheck.cpp
    clang-tools-extra/clang-tidy/hicpp/HICPPTidyModule.cpp
    clang-tools-extra/clang-tidy/hicpp/MultiwayPathsCoveredCheck.cpp
    clang-tools-extra/clang-tidy/hicpp/NoAssemblerCheck.cpp
    clang-tools-extra/clang-tidy/hicpp/SignedBitwiseCheck.cpp
    clang-tools-extra/clang-tidy/linuxkernel/LinuxKernelTidyModule.cpp
    clang-tools-extra/clang-tidy/linuxkernel/MustCheckErrsCheck.cpp
    clang-tools-extra/clang-tidy/llvm/HeaderGuardCheck.cpp
    clang-tools-extra/clang-tidy/llvm/IncludeOrderCheck.cpp
    clang-tools-extra/clang-tidy/llvm/LLVMTidyModule.cpp
    clang-tools-extra/clang-tidy/llvm/PreferIsaOrDynCastInConditionalsCheck.cpp
    clang-tools-extra/clang-tidy/llvm/PreferRegisterOverUnsignedCheck.cpp
    clang-tools-extra/clang-tidy/llvm/TwineLocalCheck.cpp
    clang-tools-extra/clang-tidy/llvmlibc/CalleeNamespaceCheck.cpp
    clang-tools-extra/clang-tidy/llvmlibc/ImplementationInNamespaceCheck.cpp
    clang-tools-extra/clang-tidy/llvmlibc/LLVMLibcTidyModule.cpp
    clang-tools-extra/clang-tidy/llvmlibc/RestrictSystemLibcHeadersCheck.cpp
    clang-tools-extra/clang-tidy/misc/ConfusableIdentifierCheck.cpp
    clang-tools-extra/clang-tidy/misc/ConstCorrectnessCheck.cpp
    clang-tools-extra/clang-tidy/misc/DefinitionsInHeadersCheck.cpp
    clang-tools-extra/clang-tidy/misc/MiscTidyModule.cpp
    clang-tools-extra/clang-tidy/misc/MisleadingIdentifier.cpp
    clang-tools-extra/clang-tidy/misc/MisplacedConstCheck.cpp
    clang-tools-extra/clang-tidy/misc/NewDeleteOverloadsCheck.cpp
    clang-tools-extra/clang-tidy/misc/NoRecursionCheck.cpp
    clang-tools-extra/clang-tidy/misc/NonCopyableObjects.cpp
    clang-tools-extra/clang-tidy/misc/NonPrivateMemberVariablesInClassesCheck.cpp
    clang-tools-extra/clang-tidy/misc/RedundantExpressionCheck.cpp
    clang-tools-extra/clang-tidy/misc/StaticAssertCheck.cpp
    clang-tools-extra/clang-tidy/misc/ThrowByValueCatchByReferenceCheck.cpp
    clang-tools-extra/clang-tidy/misc/UnconventionalAssignOperatorCheck.cpp
    clang-tools-extra/clang-tidy/misc/UniqueptrResetReleaseCheck.cpp
    clang-tools-extra/clang-tidy/misc/UnusedAliasDeclsCheck.cpp
    clang-tools-extra/clang-tidy/misc/UnusedParametersCheck.cpp
    clang-tools-extra/clang-tidy/misc/UnusedUsingDeclsCheck.cpp
    clang-tools-extra/clang-tidy/misc/UseAnonymousNamespaceCheck.cpp
    clang-tools-extra/clang-tidy/modernize/AvoidBindCheck.cpp
    clang-tools-extra/clang-tidy/modernize/AvoidCArraysCheck.cpp
    clang-tools-extra/clang-tidy/modernize/ConcatNestedNamespacesCheck.cpp
    clang-tools-extra/clang-tidy/modernize/DeprecatedHeadersCheck.cpp
    clang-tools-extra/clang-tidy/modernize/DeprecatedIosBaseAliasesCheck.cpp
    clang-tools-extra/clang-tidy/modernize/IntegralLiteralExpressionMatcher.cpp
    clang-tools-extra/clang-tidy/modernize/LoopConvertCheck.cpp
    clang-tools-extra/clang-tidy/modernize/LoopConvertUtils.cpp
    clang-tools-extra/clang-tidy/modernize/MacroToEnumCheck.cpp
    clang-tools-extra/clang-tidy/modernize/MakeSharedCheck.cpp
    clang-tools-extra/clang-tidy/modernize/MakeSmartPtrCheck.cpp
    clang-tools-extra/clang-tidy/modernize/MakeUniqueCheck.cpp
    clang-tools-extra/clang-tidy/modernize/ModernizeTidyModule.cpp
    clang-tools-extra/clang-tidy/modernize/PassByValueCheck.cpp
    clang-tools-extra/clang-tidy/modernize/RawStringLiteralCheck.cpp
    clang-tools-extra/clang-tidy/modernize/RedundantVoidArgCheck.cpp
    clang-tools-extra/clang-tidy/modernize/ReplaceAutoPtrCheck.cpp
    clang-tools-extra/clang-tidy/modernize/ReplaceDisallowCopyAndAssignMacroCheck.cpp
    clang-tools-extra/clang-tidy/modernize/ReplaceRandomShuffleCheck.cpp
    clang-tools-extra/clang-tidy/modernize/ReturnBracedInitListCheck.cpp
    clang-tools-extra/clang-tidy/modernize/ShrinkToFitCheck.cpp
    clang-tools-extra/clang-tidy/modernize/UnaryStaticAssertCheck.cpp
    clang-tools-extra/clang-tidy/modernize/UseAutoCheck.cpp
    clang-tools-extra/clang-tidy/modernize/UseBoolLiteralsCheck.cpp
    clang-tools-extra/clang-tidy/modernize/UseDefaultMemberInitCheck.cpp
    clang-tools-extra/clang-tidy/modernize/UseEmplaceCheck.cpp
    clang-tools-extra/clang-tidy/modernize/UseEqualsDefaultCheck.cpp
    clang-tools-extra/clang-tidy/modernize/UseEqualsDeleteCheck.cpp
    clang-tools-extra/clang-tidy/modernize/UseNodiscardCheck.cpp
    clang-tools-extra/clang-tidy/modernize/UseNoexceptCheck.cpp
    clang-tools-extra/clang-tidy/modernize/UseNullptrCheck.cpp
    clang-tools-extra/clang-tidy/modernize/UseOverrideCheck.cpp
    clang-tools-extra/clang-tidy/modernize/UseTrailingReturnTypeCheck.cpp
    clang-tools-extra/clang-tidy/modernize/UseTransparentFunctorsCheck.cpp
    clang-tools-extra/clang-tidy/modernize/UseUncaughtExceptionsCheck.cpp
    clang-tools-extra/clang-tidy/modernize/UseUsingCheck.cpp
    clang-tools-extra/clang-tidy/mpi/BufferDerefCheck.cpp
    clang-tools-extra/clang-tidy/mpi/MPITidyModule.cpp
    clang-tools-extra/clang-tidy/mpi/TypeMismatchCheck.cpp
    clang-tools-extra/clang-tidy/objc/AssertEquals.cpp
    clang-tools-extra/clang-tidy/objc/AvoidNSErrorInitCheck.cpp
    clang-tools-extra/clang-tidy/objc/DeallocInCategoryCheck.cpp
    clang-tools-extra/clang-tidy/objc/ForbiddenSubclassingCheck.cpp
    clang-tools-extra/clang-tidy/objc/MissingHashCheck.cpp
    clang-tools-extra/clang-tidy/objc/NSDateFormatterCheck.cpp
    clang-tools-extra/clang-tidy/objc/NSInvocationArgumentLifetimeCheck.cpp
    clang-tools-extra/clang-tidy/objc/ObjCTidyModule.cpp
    clang-tools-extra/clang-tidy/objc/PropertyDeclarationCheck.cpp
    clang-tools-extra/clang-tidy/objc/SuperSelfCheck.cpp
    clang-tools-extra/clang-tidy/openmp/ExceptionEscapeCheck.cpp
    clang-tools-extra/clang-tidy/openmp/OpenMPTidyModule.cpp
    clang-tools-extra/clang-tidy/openmp/UseDefaultNoneCheck.cpp
    clang-tools-extra/clang-tidy/performance/FasterStringFindCheck.cpp
    clang-tools-extra/clang-tidy/performance/ForRangeCopyCheck.cpp
    clang-tools-extra/clang-tidy/performance/ImplicitConversionInLoopCheck.cpp
    clang-tools-extra/clang-tidy/performance/InefficientAlgorithmCheck.cpp
    clang-tools-extra/clang-tidy/performance/InefficientStringConcatenationCheck.cpp
    clang-tools-extra/clang-tidy/performance/InefficientVectorOperationCheck.cpp
    clang-tools-extra/clang-tidy/performance/MoveConstArgCheck.cpp
    clang-tools-extra/clang-tidy/performance/MoveConstructorInitCheck.cpp
    clang-tools-extra/clang-tidy/performance/NoAutomaticMoveCheck.cpp
    clang-tools-extra/clang-tidy/performance/NoIntToPtrCheck.cpp
    clang-tools-extra/clang-tidy/performance/NoexceptMoveConstructorCheck.cpp
    clang-tools-extra/clang-tidy/performance/PerformanceTidyModule.cpp
    clang-tools-extra/clang-tidy/performance/TriviallyDestructibleCheck.cpp
    clang-tools-extra/clang-tidy/performance/TypePromotionInMathFnCheck.cpp
    clang-tools-extra/clang-tidy/performance/UnnecessaryCopyInitialization.cpp
    clang-tools-extra/clang-tidy/performance/UnnecessaryValueParamCheck.cpp
    clang-tools-extra/clang-tidy/plugin/ClangTidyPlugin.cpp
    clang-tools-extra/clang-tidy/portability/PortabilityTidyModule.cpp
    clang-tools-extra/clang-tidy/portability/RestrictSystemIncludesCheck.cpp
    clang-tools-extra/clang-tidy/portability/SIMDIntrinsicsCheck.cpp
    clang-tools-extra/clang-tidy/portability/StdAllocatorConstCheck.cpp
    clang-tools-extra/clang-tidy/readability/AvoidConstParamsInDecls.cpp
    clang-tools-extra/clang-tidy/readability/BracesAroundStatementsCheck.cpp
    clang-tools-extra/clang-tidy/readability/ConstReturnTypeCheck.cpp
    clang-tools-extra/clang-tidy/readability/ContainerContainsCheck.cpp
    clang-tools-extra/clang-tidy/readability/ContainerDataPointerCheck.cpp
    clang-tools-extra/clang-tidy/readability/ContainerSizeEmptyCheck.cpp
    clang-tools-extra/clang-tidy/readability/ConvertMemberFunctionsToStatic.cpp
    clang-tools-extra/clang-tidy/readability/DeleteNullPointerCheck.cpp
    clang-tools-extra/clang-tidy/readability/DuplicateIncludeCheck.cpp
    clang-tools-extra/clang-tidy/readability/ElseAfterReturnCheck.cpp
    clang-tools-extra/clang-tidy/readability/FunctionCognitiveComplexityCheck.cpp
    clang-tools-extra/clang-tidy/readability/FunctionSizeCheck.cpp
    clang-tools-extra/clang-tidy/readability/IdentifierLengthCheck.cpp
    clang-tools-extra/clang-tidy/readability/IdentifierNamingCheck.cpp
    clang-tools-extra/clang-tidy/readability/ImplicitBoolConversionCheck.cpp
    clang-tools-extra/clang-tidy/readability/InconsistentDeclarationParameterNameCheck.cpp
    clang-tools-extra/clang-tidy/readability/IsolateDeclarationCheck.cpp
    clang-tools-extra/clang-tidy/readability/MagicNumbersCheck.cpp
    clang-tools-extra/clang-tidy/readability/MakeMemberFunctionConstCheck.cpp
    clang-tools-extra/clang-tidy/readability/MisleadingIndentationCheck.cpp
    clang-tools-extra/clang-tidy/readability/MisplacedArrayIndexCheck.cpp
    clang-tools-extra/clang-tidy/readability/NamedParameterCheck.cpp
    clang-tools-extra/clang-tidy/readability/NamespaceCommentCheck.cpp
    clang-tools-extra/clang-tidy/readability/NonConstParameterCheck.cpp
    clang-tools-extra/clang-tidy/readability/QualifiedAutoCheck.cpp
    clang-tools-extra/clang-tidy/readability/ReadabilityTidyModule.cpp
    clang-tools-extra/clang-tidy/readability/RedundantAccessSpecifiersCheck.cpp
    clang-tools-extra/clang-tidy/readability/RedundantControlFlowCheck.cpp
    clang-tools-extra/clang-tidy/readability/RedundantDeclarationCheck.cpp
    clang-tools-extra/clang-tidy/readability/RedundantFunctionPtrDereferenceCheck.cpp
    clang-tools-extra/clang-tidy/readability/RedundantMemberInitCheck.cpp
    clang-tools-extra/clang-tidy/readability/RedundantPreprocessorCheck.cpp
    clang-tools-extra/clang-tidy/readability/RedundantSmartptrGetCheck.cpp
    clang-tools-extra/clang-tidy/readability/RedundantStringCStrCheck.cpp
    clang-tools-extra/clang-tidy/readability/RedundantStringInitCheck.cpp
    clang-tools-extra/clang-tidy/readability/SimplifyBooleanExprCheck.cpp
    clang-tools-extra/clang-tidy/readability/SimplifySubscriptExprCheck.cpp
    clang-tools-extra/clang-tidy/readability/StaticAccessedThroughInstanceCheck.cpp
    clang-tools-extra/clang-tidy/readability/StaticDefinitionInAnonymousNamespaceCheck.cpp
    clang-tools-extra/clang-tidy/readability/StringCompareCheck.cpp
    clang-tools-extra/clang-tidy/readability/SuspiciousCallArgumentCheck.cpp
    clang-tools-extra/clang-tidy/readability/UniqueptrDeleteReleaseCheck.cpp
    clang-tools-extra/clang-tidy/readability/UppercaseLiteralSuffixCheck.cpp
    clang-tools-extra/clang-tidy/readability/UseAnyOfAllOfCheck.cpp
    clang-tools-extra/clang-tidy/rename_check.py
    clang-tools-extra/clang-tidy/tool/ClangTidyMain.cpp
    clang-tools-extra/clang-tidy/utils/ASTUtils.cpp
    clang-tools-extra/clang-tidy/utils/Aliasing.cpp
    clang-tools-extra/clang-tidy/utils/DeclRefExprUtils.cpp
    clang-tools-extra/clang-tidy/utils/ExceptionAnalyzer.cpp
    clang-tools-extra/clang-tidy/utils/ExprSequence.cpp
    clang-tools-extra/clang-tidy/utils/FileExtensionsUtils.cpp
    clang-tools-extra/clang-tidy/utils/FixItHintUtils.cpp
    clang-tools-extra/clang-tidy/utils/HeaderGuard.cpp
    clang-tools-extra/clang-tidy/utils/IncludeInserter.cpp
    clang-tools-extra/clang-tidy/utils/IncludeSorter.cpp
    clang-tools-extra/clang-tidy/utils/LexerUtils.cpp
    clang-tools-extra/clang-tidy/utils/NamespaceAliaser.cpp
    clang-tools-extra/clang-tidy/utils/OptionsUtils.cpp
    clang-tools-extra/clang-tidy/utils/RenamerClangTidyCheck.cpp
    clang-tools-extra/clang-tidy/utils/TransformerClangTidyCheck.cpp
    clang-tools-extra/clang-tidy/utils/TypeTraits.cpp
    clang-tools-extra/clang-tidy/utils/UsingInserter.cpp
    clang-tools-extra/clang-tidy/zircon/TemporaryObjectsCheck.cpp
    clang-tools-extra/clang-tidy/zircon/ZirconTidyModule.cpp

Removed: 
    


################################################################################
diff  --git a/clang-tools-extra/clang-tidy/ClangTidy.cpp b/clang-tools-extra/clang-tidy/ClangTidy.cpp
index 4007363505ed6..7382bf4497b01 100644
--- a/clang-tools-extra/clang-tidy/ClangTidy.cpp
+++ b/clang-tools-extra/clang-tidy/ClangTidy.cpp
@@ -55,8 +55,7 @@ using namespace llvm;
 
 LLVM_INSTANTIATE_REGISTRY(clang::tidy::ClangTidyModuleRegistry)
 
-namespace clang {
-namespace tidy {
+namespace clang::tidy {
 
 namespace {
 #if CLANG_TIDY_ENABLE_STATIC_ANALYZER
@@ -658,5 +657,4 @@ getAllChecksAndOptions(bool AllowEnablingAnalyzerAlphaCheckers) {
 
   return Result;
 }
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy

diff  --git a/clang-tools-extra/clang-tidy/ClangTidyCheck.cpp b/clang-tools-extra/clang-tidy/ClangTidyCheck.cpp
index 498140e5f13a5..18169deaa0681 100644
--- a/clang-tools-extra/clang-tidy/ClangTidyCheck.cpp
+++ b/clang-tools-extra/clang-tidy/ClangTidyCheck.cpp
@@ -13,8 +13,7 @@
 #include "llvm/Support/YAMLParser.h"
 #include <optional>
 
-namespace clang {
-namespace tidy {
+namespace clang::tidy {
 
 ClangTidyCheck::ClangTidyCheck(StringRef CheckName, ClangTidyContext *Context)
     : CheckName(CheckName), Context(Context),
@@ -225,5 +224,4 @@ ClangTidyCheck::OptionsView::getLocalOrGlobal(StringRef LocalName,
                                               StringRef Default) const {
   return getLocalOrGlobal(LocalName).value_or(Default);
 }
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy

diff  --git a/clang-tools-extra/clang-tidy/ClangTidyDiagnosticConsumer.cpp b/clang-tools-extra/clang-tidy/ClangTidyDiagnosticConsumer.cpp
index 558190e5e13b5..11ee7a09a112b 100644
--- a/clang-tools-extra/clang-tidy/ClangTidyDiagnosticConsumer.cpp
+++ b/clang-tools-extra/clang-tidy/ClangTidyDiagnosticConsumer.cpp
@@ -319,8 +319,7 @@ void ClangTidyDiagnosticConsumer::finalizeLastError() {
   LastErrorPassesLineFilter = false;
 }
 
-namespace clang {
-namespace tidy {
+namespace clang::tidy {
 
 const llvm::StringMap<tooling::Replacements> *
 getFixIt(const tooling::Diagnostic &Diagnostic, bool GetFixFromNotes) {
@@ -340,8 +339,7 @@ getFixIt(const tooling::Diagnostic &Diagnostic, bool GetFixFromNotes) {
   return Result;
 }
 
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy
 
 void ClangTidyDiagnosticConsumer::HandleDiagnostic(
     DiagnosticsEngine::Level DiagLevel, const Diagnostic &Info) {

diff  --git a/clang-tools-extra/clang-tidy/ClangTidyModule.cpp b/clang-tools-extra/clang-tidy/ClangTidyModule.cpp
index 67366433f79a7..8650e46b8833e 100644
--- a/clang-tools-extra/clang-tidy/ClangTidyModule.cpp
+++ b/clang-tools-extra/clang-tidy/ClangTidyModule.cpp
@@ -13,8 +13,7 @@
 #include "ClangTidyModule.h"
 #include "ClangTidyCheck.h"
 
-namespace clang {
-namespace tidy {
+namespace clang::tidy {
 
 void ClangTidyCheckFactories::registerCheckFactory(StringRef Name,
                                                    CheckFactory Factory) {
@@ -51,5 +50,4 @@ ClangTidyOptions ClangTidyModule::getModuleOptions() {
   return ClangTidyOptions();
 }
 
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy

diff  --git a/clang-tools-extra/clang-tidy/ClangTidyOptions.cpp b/clang-tools-extra/clang-tidy/ClangTidyOptions.cpp
index 7d26e34192b61..808929b11f796 100644
--- a/clang-tools-extra/clang-tidy/ClangTidyOptions.cpp
+++ b/clang-tools-extra/clang-tidy/ClangTidyOptions.cpp
@@ -28,8 +28,7 @@ using OptionsSource = clang::tidy::ClangTidyOptionsProvider::OptionsSource;
 LLVM_YAML_IS_FLOW_SEQUENCE_VECTOR(FileFilter)
 LLVM_YAML_IS_FLOW_SEQUENCE_VECTOR(FileFilter::LineRange)
 
-namespace llvm {
-namespace yaml {
+namespace llvm::yaml {
 
 // Map std::pair<int, int> to a JSON array of size 2.
 template <> struct SequenceTraits<FileFilter::LineRange> {
@@ -135,11 +134,9 @@ template <> struct MappingTraits<ClangTidyOptions> {
   }
 };
 
-} // namespace yaml
-} // namespace llvm
+} // namespace llvm::yaml
 
-namespace clang {
-namespace tidy {
+namespace clang::tidy {
 
 ClangTidyOptions ClangTidyOptions::getDefaults() {
   ClangTidyOptions Options;
@@ -452,5 +449,4 @@ std::string configurationAsText(const ClangTidyOptions &Options) {
   return Stream.str();
 }
 
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy

diff  --git a/clang-tools-extra/clang-tidy/ClangTidyProfiling.cpp b/clang-tools-extra/clang-tidy/ClangTidyProfiling.cpp
index 3a03dc033f802..14dfe963c9db3 100644
--- a/clang-tools-extra/clang-tidy/ClangTidyProfiling.cpp
+++ b/clang-tools-extra/clang-tidy/ClangTidyProfiling.cpp
@@ -17,8 +17,7 @@
 
 #define DEBUG_TYPE "clang-tidy-profiling"
 
-namespace clang {
-namespace tidy {
+namespace clang::tidy {
 
 ClangTidyProfiling::StorageParams::StorageParams(llvm::StringRef ProfilePrefix,
                                                  llvm::StringRef SourceFile)
@@ -87,5 +86,4 @@ ClangTidyProfiling::~ClangTidyProfiling() {
     storeProfileData();
 }
 
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy

diff  --git a/clang-tools-extra/clang-tidy/ExpandModularHeadersPPCallbacks.cpp b/clang-tools-extra/clang-tidy/ExpandModularHeadersPPCallbacks.cpp
index 32465a4dc0ba1..a20fe23b17de8 100644
--- a/clang-tools-extra/clang-tidy/ExpandModularHeadersPPCallbacks.cpp
+++ b/clang-tools-extra/clang-tidy/ExpandModularHeadersPPCallbacks.cpp
@@ -16,8 +16,7 @@
 
 #define DEBUG_TYPE "clang-tidy"
 
-namespace clang {
-namespace tooling {
+namespace clang::tooling {
 
 class ExpandModularHeadersPPCallbacks::FileRecorder {
 public:
@@ -306,5 +305,4 @@ void ExpandModularHeadersPPCallbacks::Endif(SourceLocation Loc,
   parseToLocation(Loc);
 }
 
-} // namespace tooling
-} // namespace clang
+} // namespace clang::tooling

diff  --git a/clang-tools-extra/clang-tidy/GlobList.cpp b/clang-tools-extra/clang-tidy/GlobList.cpp
index 15d856ea3e10c..acd08dd3ee08c 100644
--- a/clang-tools-extra/clang-tidy/GlobList.cpp
+++ b/clang-tools-extra/clang-tidy/GlobList.cpp
@@ -10,8 +10,7 @@
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/SmallString.h"
 
-namespace clang {
-namespace tidy {
+namespace clang::tidy {
 
 // Returns true if GlobList starts with the negative indicator ('-'), removes it
 // from the GlobList.
@@ -73,5 +72,4 @@ bool CachedGlobList::contains(StringRef S) const {
   return Value;
 }
 
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy

diff  --git a/clang-tools-extra/clang-tidy/NoLintDirectiveHandler.cpp b/clang-tools-extra/clang-tidy/NoLintDirectiveHandler.cpp
index 9f4b7562a805e..45d00dc16c113 100644
--- a/clang-tools-extra/clang-tidy/NoLintDirectiveHandler.cpp
+++ b/clang-tools-extra/clang-tidy/NoLintDirectiveHandler.cpp
@@ -33,8 +33,7 @@
 #include <type_traits>
 #include <utility>
 
-namespace clang {
-namespace tidy {
+namespace clang::tidy {
 
 //===----------------------------------------------------------------------===//
 // NoLintType
@@ -411,5 +410,4 @@ bool NoLintDirectiveHandler::shouldSuppress(
                                EnableNoLintBlocks);
 }
 
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy

diff  --git a/clang-tools-extra/clang-tidy/abseil/AbseilTidyModule.cpp b/clang-tools-extra/clang-tidy/abseil/AbseilTidyModule.cpp
index 5d99e6b500754..09a09e6c599b0 100644
--- a/clang-tools-extra/clang-tidy/abseil/AbseilTidyModule.cpp
+++ b/clang-tools-extra/clang-tidy/abseil/AbseilTidyModule.cpp
@@ -29,8 +29,7 @@
 #include "TimeSubtractionCheck.h"
 #include "UpgradeDurationConversionsCheck.h"
 
-namespace clang {
-namespace tidy {
+namespace clang::tidy {
 namespace abseil {
 
 class AbseilModule : public ClangTidyModule {
@@ -85,5 +84,4 @@ static ClangTidyModuleRegistry::Add<AbseilModule> X("abseil-module",
 // and thus register the AbseilModule.
 volatile int AbseilModuleAnchorSource = 0;
 
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy

diff  --git a/clang-tools-extra/clang-tidy/abseil/CleanupCtadCheck.cpp b/clang-tools-extra/clang-tidy/abseil/CleanupCtadCheck.cpp
index e6617fb7dd89e..06f98c76269b5 100644
--- a/clang-tools-extra/clang-tidy/abseil/CleanupCtadCheck.cpp
+++ b/clang-tools-extra/clang-tidy/abseil/CleanupCtadCheck.cpp
@@ -19,9 +19,7 @@
 using namespace ::clang::ast_matchers;
 using namespace ::clang::transformer;
 
-namespace clang {
-namespace tidy {
-namespace abseil {
+namespace clang::tidy::abseil {
 
 RewriteRuleWith<std::string> CleanupCtadCheckImpl() {
   auto warning_message = cat("prefer absl::Cleanup's class template argument "
@@ -42,6 +40,4 @@ RewriteRuleWith<std::string> CleanupCtadCheckImpl() {
 CleanupCtadCheck::CleanupCtadCheck(StringRef Name, ClangTidyContext *Context)
     : utils::TransformerClangTidyCheck(CleanupCtadCheckImpl(), Name, Context) {}
 
-} // namespace abseil
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::abseil

diff  --git a/clang-tools-extra/clang-tidy/abseil/DurationAdditionCheck.cpp b/clang-tools-extra/clang-tidy/abseil/DurationAdditionCheck.cpp
index edf6a174ef525..2a31d60961703 100644
--- a/clang-tools-extra/clang-tidy/abseil/DurationAdditionCheck.cpp
+++ b/clang-tools-extra/clang-tidy/abseil/DurationAdditionCheck.cpp
@@ -15,9 +15,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace abseil {
+namespace clang::tidy::abseil {
 
 void DurationAdditionCheck::registerMatchers(MatchFinder *Finder) {
   Finder->addMatcher(
@@ -69,6 +67,4 @@ void DurationAdditionCheck::check(const MatchFinder::MatchResult &Result) {
   diag(Binop->getBeginLoc(), "perform addition in the duration domain") << Hint;
 }
 
-} // namespace abseil
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::abseil

diff  --git a/clang-tools-extra/clang-tidy/abseil/DurationComparisonCheck.cpp b/clang-tools-extra/clang-tidy/abseil/DurationComparisonCheck.cpp
index 859aad7a579db..59b4a52165b59 100644
--- a/clang-tools-extra/clang-tidy/abseil/DurationComparisonCheck.cpp
+++ b/clang-tools-extra/clang-tidy/abseil/DurationComparisonCheck.cpp
@@ -15,9 +15,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace abseil {
+namespace clang::tidy::abseil {
 
 void DurationComparisonCheck::registerMatchers(MatchFinder *Finder) {
   auto Matcher = expr(comparisonOperatorWithCallee(functionDecl(
@@ -55,6 +53,4 @@ void DurationComparisonCheck::check(const MatchFinder::MatchResult &Result) {
                                           .str());
 }
 
-} // namespace abseil
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::abseil

diff  --git a/clang-tools-extra/clang-tidy/abseil/DurationConversionCastCheck.cpp b/clang-tools-extra/clang-tidy/abseil/DurationConversionCastCheck.cpp
index 328f6f13b80b3..869a0ec44556c 100644
--- a/clang-tools-extra/clang-tidy/abseil/DurationConversionCastCheck.cpp
+++ b/clang-tools-extra/clang-tidy/abseil/DurationConversionCastCheck.cpp
@@ -15,9 +15,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace abseil {
+namespace clang::tidy::abseil {
 
 void DurationConversionCastCheck::registerMatchers(MatchFinder *Finder) {
   auto CallMatcher = ignoringImpCasts(callExpr(
@@ -81,6 +79,4 @@ void DurationConversionCastCheck::check(
   }
 }
 
-} // namespace abseil
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::abseil

diff  --git a/clang-tools-extra/clang-tidy/abseil/DurationDivisionCheck.cpp b/clang-tools-extra/clang-tidy/abseil/DurationDivisionCheck.cpp
index 0fb750c694754..50e2d0366c768 100644
--- a/clang-tools-extra/clang-tidy/abseil/DurationDivisionCheck.cpp
+++ b/clang-tools-extra/clang-tidy/abseil/DurationDivisionCheck.cpp
@@ -11,9 +11,7 @@
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/Lex/Lexer.h"
 
-namespace clang {
-namespace tidy {
-namespace abseil {
+namespace clang::tidy::abseil {
 
 using namespace clang::ast_matchers;
 
@@ -52,6 +50,4 @@ void DurationDivisionCheck::check(const MatchFinder::MatchResult &Result) {
              ")");
 }
 
-} // namespace abseil
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::abseil

diff  --git a/clang-tools-extra/clang-tidy/abseil/DurationFactoryFloatCheck.cpp b/clang-tools-extra/clang-tidy/abseil/DurationFactoryFloatCheck.cpp
index fcb4a8550a6a8..6cb687de4dc86 100644
--- a/clang-tools-extra/clang-tidy/abseil/DurationFactoryFloatCheck.cpp
+++ b/clang-tools-extra/clang-tidy/abseil/DurationFactoryFloatCheck.cpp
@@ -16,9 +16,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace abseil {
+namespace clang::tidy::abseil {
 
 // Returns `true` if `Range` is inside a macro definition.
 static bool insideMacroDefinition(const MatchFinder::MatchResult &Result,
@@ -66,6 +64,4 @@ void DurationFactoryFloatCheck::check(const MatchFinder::MatchResult &Result) {
   }
 }
 
-} // namespace abseil
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::abseil

diff  --git a/clang-tools-extra/clang-tidy/abseil/DurationFactoryScaleCheck.cpp b/clang-tools-extra/clang-tidy/abseil/DurationFactoryScaleCheck.cpp
index 24b3f56d2b455..5688dc16d1106 100644
--- a/clang-tools-extra/clang-tidy/abseil/DurationFactoryScaleCheck.cpp
+++ b/clang-tools-extra/clang-tidy/abseil/DurationFactoryScaleCheck.cpp
@@ -15,9 +15,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace abseil {
+namespace clang::tidy::abseil {
 
 // Given the name of a duration factory function, return the appropriate
 // `DurationScale` for that factory.  If no factory can be found for
@@ -224,6 +222,4 @@ void DurationFactoryScaleCheck::check(const MatchFinder::MatchResult &Result) {
   }
 }
 
-} // namespace abseil
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::abseil

diff  --git a/clang-tools-extra/clang-tidy/abseil/DurationRewriter.cpp b/clang-tools-extra/clang-tidy/abseil/DurationRewriter.cpp
index d96093fdd8d2b..2790a205d2680 100644
--- a/clang-tools-extra/clang-tidy/abseil/DurationRewriter.cpp
+++ b/clang-tools-extra/clang-tidy/abseil/DurationRewriter.cpp
@@ -15,9 +15,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace abseil {
+namespace clang::tidy::abseil {
 
 struct DurationScale2IndexFunctor {
   using argument_type = DurationScale;
@@ -322,6 +320,4 @@ bool isInMacro(const MatchFinder::MatchResult &Result, const Expr *E) {
   return Loc.isMacroID();
 }
 
-} // namespace abseil
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::abseil

diff  --git a/clang-tools-extra/clang-tidy/abseil/DurationSubtractionCheck.cpp b/clang-tools-extra/clang-tidy/abseil/DurationSubtractionCheck.cpp
index 21425b4f6fa7a..48600298a20ca 100644
--- a/clang-tools-extra/clang-tidy/abseil/DurationSubtractionCheck.cpp
+++ b/clang-tools-extra/clang-tidy/abseil/DurationSubtractionCheck.cpp
@@ -15,9 +15,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace abseil {
+namespace clang::tidy::abseil {
 
 void DurationSubtractionCheck::registerMatchers(MatchFinder *Finder) {
   Finder->addMatcher(
@@ -57,6 +55,4 @@ void DurationSubtractionCheck::check(const MatchFinder::MatchResult &Result) {
                  .str());
 }
 
-} // namespace abseil
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::abseil

diff  --git a/clang-tools-extra/clang-tidy/abseil/DurationUnnecessaryConversionCheck.cpp b/clang-tools-extra/clang-tidy/abseil/DurationUnnecessaryConversionCheck.cpp
index b357d80f43624..9bb1fd57a4401 100644
--- a/clang-tools-extra/clang-tidy/abseil/DurationUnnecessaryConversionCheck.cpp
+++ b/clang-tools-extra/clang-tidy/abseil/DurationUnnecessaryConversionCheck.cpp
@@ -15,9 +15,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace abseil {
+namespace clang::tidy::abseil {
 
 void DurationUnnecessaryConversionCheck::registerMatchers(MatchFinder *Finder) {
   for (const auto &Scale : {"Hours", "Minutes", "Seconds", "Milliseconds",
@@ -113,6 +111,4 @@ void DurationUnnecessaryConversionCheck::check(
       << Hint;
 }
 
-} // namespace abseil
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::abseil

diff  --git a/clang-tools-extra/clang-tidy/abseil/FasterStrsplitDelimiterCheck.cpp b/clang-tools-extra/clang-tidy/abseil/FasterStrsplitDelimiterCheck.cpp
index 02d96dbd402aa..bda9b9ec34e63 100644
--- a/clang-tools-extra/clang-tidy/abseil/FasterStrsplitDelimiterCheck.cpp
+++ b/clang-tools-extra/clang-tidy/abseil/FasterStrsplitDelimiterCheck.cpp
@@ -14,9 +14,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace abseil {
+namespace clang::tidy::abseil {
 
 namespace {
 
@@ -125,6 +123,4 @@ void FasterStrsplitDelimiterCheck::check(
                                       *Replacement);
 }
 
-} // namespace abseil
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::abseil

diff  --git a/clang-tools-extra/clang-tidy/abseil/NoInternalDependenciesCheck.cpp b/clang-tools-extra/clang-tidy/abseil/NoInternalDependenciesCheck.cpp
index ee0da4b50bf9c..d04afa48e18de 100644
--- a/clang-tools-extra/clang-tidy/abseil/NoInternalDependenciesCheck.cpp
+++ b/clang-tools-extra/clang-tidy/abseil/NoInternalDependenciesCheck.cpp
@@ -13,9 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace abseil {
+namespace clang::tidy::abseil {
 
 void NoInternalDependenciesCheck::registerMatchers(MatchFinder *Finder) {
   // TODO: refactor matcher to be configurable or just match on any internal
@@ -45,6 +43,4 @@ void NoInternalDependenciesCheck::check(const MatchFinder::MatchResult &Result)
        "details are reserved to Abseil");
 }
 
-} // namespace abseil
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::abseil

diff  --git a/clang-tools-extra/clang-tidy/abseil/NoNamespaceCheck.cpp b/clang-tools-extra/clang-tidy/abseil/NoNamespaceCheck.cpp
index 4e7b09378db0c..ec011bd4fe0e3 100644
--- a/clang-tools-extra/clang-tidy/abseil/NoNamespaceCheck.cpp
+++ b/clang-tools-extra/clang-tidy/abseil/NoNamespaceCheck.cpp
@@ -13,9 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace abseil {
+namespace clang::tidy::abseil {
 
 void NoNamespaceCheck::registerMatchers(MatchFinder *Finder) {
   Finder->addMatcher(
@@ -33,6 +31,4 @@ void NoNamespaceCheck::check(const MatchFinder::MatchResult &Result) {
        "and should not be opened in user code");
 }
 
-} // namespace abseil
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::abseil

diff  --git a/clang-tools-extra/clang-tidy/abseil/RedundantStrcatCallsCheck.cpp b/clang-tools-extra/clang-tidy/abseil/RedundantStrcatCallsCheck.cpp
index 15171be5de2d8..2eed10bbf6e6c 100644
--- a/clang-tools-extra/clang-tidy/abseil/RedundantStrcatCallsCheck.cpp
+++ b/clang-tools-extra/clang-tidy/abseil/RedundantStrcatCallsCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace abseil {
+namespace clang::tidy::abseil {
 
 // TODO: Features to add to the check:
 //  - Make it work if num_args > 26.
@@ -134,6 +132,4 @@ void RedundantStrcatCallsCheck::check(const MatchFinder::MatchResult& Result) {
       << CheckResult.Hints;
 }
 
-}  // namespace abseil
-}  // namespace tidy
-}  // namespace clang
+} // namespace clang::tidy::abseil

diff  --git a/clang-tools-extra/clang-tidy/abseil/StrCatAppendCheck.cpp b/clang-tools-extra/clang-tidy/abseil/StrCatAppendCheck.cpp
index a2586beac3879..ab6ed701e59fe 100644
--- a/clang-tools-extra/clang-tidy/abseil/StrCatAppendCheck.cpp
+++ b/clang-tools-extra/clang-tidy/abseil/StrCatAppendCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace abseil {
+namespace clang::tidy::abseil {
 
 namespace {
 // Skips any combination of temporary materialization, temporary binding and
@@ -97,6 +95,4 @@ void StrCatAppendCheck::check(const MatchFinder::MatchResult &Result) {
       << FixItHint::CreateInsertion(Call->getArg(0)->getBeginLoc(), "&");
 }
 
-}  // namespace abseil
-}  // namespace tidy
-}  // namespace clang
+} // namespace clang::tidy::abseil

diff  --git a/clang-tools-extra/clang-tidy/abseil/StringFindStartswithCheck.cpp b/clang-tools-extra/clang-tidy/abseil/StringFindStartswithCheck.cpp
index 19e68975945e5..7effb8250ae76 100644
--- a/clang-tools-extra/clang-tidy/abseil/StringFindStartswithCheck.cpp
+++ b/clang-tools-extra/clang-tidy/abseil/StringFindStartswithCheck.cpp
@@ -17,9 +17,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace abseil {
+namespace clang::tidy::abseil {
 
 StringFindStartswithCheck::StringFindStartswithCheck(StringRef Name,
                                                      ClangTidyContext *Context)
@@ -142,6 +140,4 @@ void StringFindStartswithCheck::storeOptions(
   Options.store(Opts, "AbseilStringsMatchHeader", AbseilStringsMatchHeader);
 }
 
-} // namespace abseil
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::abseil

diff  --git a/clang-tools-extra/clang-tidy/abseil/StringFindStrContainsCheck.cpp b/clang-tools-extra/clang-tidy/abseil/StringFindStrContainsCheck.cpp
index b3bc3821dbd58..28b2f81fdc8c8 100644
--- a/clang-tools-extra/clang-tidy/abseil/StringFindStrContainsCheck.cpp
+++ b/clang-tools-extra/clang-tidy/abseil/StringFindStrContainsCheck.cpp
@@ -20,9 +20,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace abseil {
+namespace clang::tidy::abseil {
 
 using ::clang::transformer::addInclude;
 using ::clang::transformer::applyFirst;
@@ -107,6 +105,4 @@ void StringFindStrContainsCheck::storeOptions(
                 AbseilStringsMatchHeaderOption);
 }
 
-} // namespace abseil
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::abseil

diff  --git a/clang-tools-extra/clang-tidy/abseil/TimeComparisonCheck.cpp b/clang-tools-extra/clang-tidy/abseil/TimeComparisonCheck.cpp
index fa6fcd877b799..d105786129d98 100644
--- a/clang-tools-extra/clang-tidy/abseil/TimeComparisonCheck.cpp
+++ b/clang-tools-extra/clang-tidy/abseil/TimeComparisonCheck.cpp
@@ -16,9 +16,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace abseil {
+namespace clang::tidy::abseil {
 
 void TimeComparisonCheck::registerMatchers(MatchFinder *Finder) {
   auto Matcher =
@@ -57,6 +55,4 @@ void TimeComparisonCheck::check(const MatchFinder::MatchResult &Result) {
                                           .str());
 }
 
-} // namespace abseil
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::abseil

diff  --git a/clang-tools-extra/clang-tidy/abseil/TimeSubtractionCheck.cpp b/clang-tools-extra/clang-tidy/abseil/TimeSubtractionCheck.cpp
index 7e8a94e0ecb45..a2171aad32b73 100644
--- a/clang-tools-extra/clang-tidy/abseil/TimeSubtractionCheck.cpp
+++ b/clang-tools-extra/clang-tidy/abseil/TimeSubtractionCheck.cpp
@@ -16,9 +16,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace abseil {
+namespace clang::tidy::abseil {
 
 // Returns `true` if `Range` is inside a macro definition.
 static bool insideMacroDefinition(const MatchFinder::MatchResult &Result,
@@ -197,6 +195,4 @@ void TimeSubtractionCheck::check(const MatchFinder::MatchResult &Result) {
   }
 }
 
-} // namespace abseil
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::abseil

diff  --git a/clang-tools-extra/clang-tidy/abseil/UpgradeDurationConversionsCheck.cpp b/clang-tools-extra/clang-tidy/abseil/UpgradeDurationConversionsCheck.cpp
index 539b575d18800..8e27e8e3e0c2b 100644
--- a/clang-tools-extra/clang-tidy/abseil/UpgradeDurationConversionsCheck.cpp
+++ b/clang-tools-extra/clang-tidy/abseil/UpgradeDurationConversionsCheck.cpp
@@ -14,9 +14,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace abseil {
+namespace clang::tidy::abseil {
 
 void UpgradeDurationConversionsCheck::registerMatchers(MatchFinder *Finder) {
   // For the arithmetic calls, we match only the uses of the templated operators
@@ -160,6 +158,4 @@ void UpgradeDurationConversionsCheck::check(
        << FixItHint::CreateInsertion(SourceRange.getEnd(), ")");
 }
 
-} // namespace abseil
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::abseil

diff  --git a/clang-tools-extra/clang-tidy/add_new_check.py b/clang-tools-extra/clang-tidy/add_new_check.py
index e3ad7a286a444..8c5e140c47050 100755
--- a/clang-tools-extra/clang-tidy/add_new_check.py
+++ b/clang-tools-extra/clang-tidy/add_new_check.py
@@ -77,9 +77,7 @@ def write_header(module_path, module, namespace, check_name, check_name_camel):
 
 #include "../ClangTidyCheck.h"
 
-namespace clang {
-namespace tidy {
-namespace %(namespace)s {
+namespace clang::tidy::%(namespace)s {
 
 /// FIXME: Write a short description.
 ///
@@ -93,9 +91,7 @@ class %(check_name_camel)s : public ClangTidyCheck {
   void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
 };
 
-} // namespace %(namespace)s
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::%(namespace)s
 
 #endif // %(header_guard)s
 """ % {'header_guard': header_guard,
@@ -129,9 +125,7 @@ def write_implementation(module_path, module, namespace, check_name_camel):
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace %(namespace)s {
+namespace clang::tidy::%(namespace)s {
 
 void %(check_name)s::registerMatchers(MatchFinder *Finder) {
   // FIXME: Add matchers.
@@ -149,9 +143,7 @@ def write_implementation(module_path, module, namespace, check_name_camel):
       << FixItHint::CreateInsertion(MatchedDecl->getLocation(), "awesome_");
 }
 
-} // namespace %(namespace)s
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::%(namespace)s
 """ % {'check_name': check_name_camel,
        'module': module,
        'namespace': namespace})

diff  --git a/clang-tools-extra/clang-tidy/altera/AlteraTidyModule.cpp b/clang-tools-extra/clang-tidy/altera/AlteraTidyModule.cpp
index 17458771d6358..21610c7d1eced 100644
--- a/clang-tools-extra/clang-tidy/altera/AlteraTidyModule.cpp
+++ b/clang-tools-extra/clang-tidy/altera/AlteraTidyModule.cpp
@@ -17,8 +17,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
+namespace clang::tidy {
 namespace altera {
 
 class AlteraModule : public ClangTidyModule {
@@ -46,5 +45,4 @@ static ClangTidyModuleRegistry::Add<altera::AlteraModule>
 // and thus register the AlteraModule.
 volatile int AlteraModuleAnchorSource = 0;
 
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy

diff  --git a/clang-tools-extra/clang-tidy/altera/IdDependentBackwardBranchCheck.cpp b/clang-tools-extra/clang-tidy/altera/IdDependentBackwardBranchCheck.cpp
index 09cddb220877a..66e6d97f500ce 100644
--- a/clang-tools-extra/clang-tidy/altera/IdDependentBackwardBranchCheck.cpp
+++ b/clang-tools-extra/clang-tidy/altera/IdDependentBackwardBranchCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace altera {
+namespace clang::tidy::altera {
 
 void IdDependentBackwardBranchCheck::registerMatchers(MatchFinder *Finder) {
   // Prototype to identify all variables which hold a thread-variant ID.
@@ -259,6 +257,4 @@ void IdDependentBackwardBranchCheck::check(
   }
 }
 
-} // namespace altera
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::altera

diff  --git a/clang-tools-extra/clang-tidy/altera/KernelNameRestrictionCheck.cpp b/clang-tools-extra/clang-tidy/altera/KernelNameRestrictionCheck.cpp
index ddf09ca2a5c69..f88b70b8d02aa 100644
--- a/clang-tools-extra/clang-tidy/altera/KernelNameRestrictionCheck.cpp
+++ b/clang-tools-extra/clang-tidy/altera/KernelNameRestrictionCheck.cpp
@@ -15,9 +15,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace altera {
+namespace clang::tidy::altera {
 
 namespace {
 
@@ -102,6 +100,4 @@ void KernelNameRestrictionPPCallbacks::EndOfMainFile() {
   }
 }
 
-} // namespace altera
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::altera

diff  --git a/clang-tools-extra/clang-tidy/altera/SingleWorkItemBarrierCheck.cpp b/clang-tools-extra/clang-tidy/altera/SingleWorkItemBarrierCheck.cpp
index 759c81c34ca64..a4e7cf4835b91 100644
--- a/clang-tools-extra/clang-tidy/altera/SingleWorkItemBarrierCheck.cpp
+++ b/clang-tools-extra/clang-tidy/altera/SingleWorkItemBarrierCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace altera {
+namespace clang::tidy::altera {
 
 void SingleWorkItemBarrierCheck::registerMatchers(MatchFinder *Finder) {
   // Find any function that calls barrier but does not call an ID function.
@@ -79,6 +77,4 @@ void SingleWorkItemBarrierCheck::storeOptions(
   Options.store(Opts, "AOCVersion", AOCVersion);
 }
 
-} // namespace altera
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::altera

diff  --git a/clang-tools-extra/clang-tidy/altera/StructPackAlignCheck.cpp b/clang-tools-extra/clang-tidy/altera/StructPackAlignCheck.cpp
index b5f8d082d8877..70a6ab3cc8f3b 100644
--- a/clang-tools-extra/clang-tidy/altera/StructPackAlignCheck.cpp
+++ b/clang-tools-extra/clang-tidy/altera/StructPackAlignCheck.cpp
@@ -14,9 +14,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace altera {
+namespace clang::tidy::altera {
 
 void StructPackAlignCheck::registerMatchers(MatchFinder *Finder) {
   Finder->addMatcher(recordDecl(isStruct(), isDefinition(),
@@ -143,6 +141,4 @@ void StructPackAlignCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
   Options.store(Opts, "MaxConfiguredAlignment", MaxConfiguredAlignment);
 }
 
-} // namespace altera
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::altera

diff  --git a/clang-tools-extra/clang-tidy/altera/UnrollLoopsCheck.cpp b/clang-tools-extra/clang-tidy/altera/UnrollLoopsCheck.cpp
index 75797c185decd..667c1b92390a6 100644
--- a/clang-tools-extra/clang-tidy/altera/UnrollLoopsCheck.cpp
+++ b/clang-tools-extra/clang-tidy/altera/UnrollLoopsCheck.cpp
@@ -17,9 +17,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace altera {
+namespace clang::tidy::altera {
 
 UnrollLoopsCheck::UnrollLoopsCheck(StringRef Name, ClangTidyContext *Context)
     : ClangTidyCheck(Name, Context),
@@ -267,6 +265,4 @@ void UnrollLoopsCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
   Options.store(Opts, "MaxLoopIterations", MaxLoopIterations);
 }
 
-} // namespace altera
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::altera

diff  --git a/clang-tools-extra/clang-tidy/android/AndroidTidyModule.cpp b/clang-tools-extra/clang-tidy/android/AndroidTidyModule.cpp
index b24c0d992eab7..4541e926e8864 100644
--- a/clang-tools-extra/clang-tidy/android/AndroidTidyModule.cpp
+++ b/clang-tools-extra/clang-tidy/android/AndroidTidyModule.cpp
@@ -27,8 +27,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
+namespace clang::tidy {
 namespace android {
 
 /// This module is for Android specific checks.
@@ -69,5 +68,4 @@ static ClangTidyModuleRegistry::Add<AndroidModule>
 // and thus register the AndroidModule.
 volatile int AndroidModuleAnchorSource = 0;
 
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy

diff  --git a/clang-tools-extra/clang-tidy/android/CloexecAccept4Check.cpp b/clang-tools-extra/clang-tidy/android/CloexecAccept4Check.cpp
index fe1f341fa1b1f..77dca9be89580 100644
--- a/clang-tools-extra/clang-tidy/android/CloexecAccept4Check.cpp
+++ b/clang-tools-extra/clang-tidy/android/CloexecAccept4Check.cpp
@@ -13,9 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace android {
+namespace clang::tidy::android {
 
 void CloexecAccept4Check::registerMatchers(MatchFinder *Finder) {
   auto SockAddrPointerType =
@@ -34,6 +32,4 @@ void CloexecAccept4Check::check(const MatchFinder::MatchResult &Result) {
   insertMacroFlag(Result, /*MacroFlag=*/"SOCK_CLOEXEC", /*ArgPos=*/3);
 }
 
-} // namespace android
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::android

diff  --git a/clang-tools-extra/clang-tidy/android/CloexecAcceptCheck.cpp b/clang-tools-extra/clang-tidy/android/CloexecAcceptCheck.cpp
index b79c55417077c..80be6fe326a28 100644
--- a/clang-tools-extra/clang-tidy/android/CloexecAcceptCheck.cpp
+++ b/clang-tools-extra/clang-tidy/android/CloexecAcceptCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace android {
+namespace clang::tidy::android {
 
 void CloexecAcceptCheck::registerMatchers(MatchFinder *Finder) {
   auto SockAddrPointerType =
@@ -41,6 +39,4 @@ void CloexecAcceptCheck::check(const MatchFinder::MatchResult &Result) {
       ReplacementText);
 }
 
-} // namespace android
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::android

diff  --git a/clang-tools-extra/clang-tidy/android/CloexecCheck.cpp b/clang-tools-extra/clang-tidy/android/CloexecCheck.cpp
index d373877713f18..39a0d74f38360 100644
--- a/clang-tools-extra/clang-tidy/android/CloexecCheck.cpp
+++ b/clang-tools-extra/clang-tidy/android/CloexecCheck.cpp
@@ -14,9 +14,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace android {
+namespace clang::tidy::android {
 
 namespace {
 // Helper function to form the correct string mode for Type3.
@@ -108,6 +106,4 @@ StringRef CloexecCheck::getSpellingArg(const MatchFinder::MatchResult &Result,
       SM, Result.Context->getLangOpts());
 }
 
-} // namespace android
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::android

diff  --git a/clang-tools-extra/clang-tidy/android/CloexecCreatCheck.cpp b/clang-tools-extra/clang-tidy/android/CloexecCreatCheck.cpp
index f096884d86d86..514f11ff15c3d 100644
--- a/clang-tools-extra/clang-tidy/android/CloexecCreatCheck.cpp
+++ b/clang-tools-extra/clang-tidy/android/CloexecCreatCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace android {
+namespace clang::tidy::android {
 
 void CloexecCreatCheck::registerMatchers(MatchFinder *Finder) {
   auto CharPointerType = hasType(pointerType(pointee(isAnyCharacter())));
@@ -37,6 +35,4 @@ void CloexecCreatCheck::check(const MatchFinder::MatchResult &Result) {
               ReplacementText);
 }
 
-} // namespace android
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::android

diff  --git a/clang-tools-extra/clang-tidy/android/CloexecDupCheck.cpp b/clang-tools-extra/clang-tidy/android/CloexecDupCheck.cpp
index 1f068d49f777e..fad7bbdd8cffc 100644
--- a/clang-tools-extra/clang-tidy/android/CloexecDupCheck.cpp
+++ b/clang-tools-extra/clang-tidy/android/CloexecDupCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace android {
+namespace clang::tidy::android {
 
 void CloexecDupCheck::registerMatchers(MatchFinder *Finder) {
   registerMatchersImpl(Finder,
@@ -32,6 +30,4 @@ void CloexecDupCheck::check(const MatchFinder::MatchResult &Result) {
               ReplacementText);
 }
 
-} // namespace android
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::android

diff  --git a/clang-tools-extra/clang-tidy/android/CloexecEpollCreate1Check.cpp b/clang-tools-extra/clang-tidy/android/CloexecEpollCreate1Check.cpp
index 8fb175eef6da8..1c5919c689672 100644
--- a/clang-tools-extra/clang-tidy/android/CloexecEpollCreate1Check.cpp
+++ b/clang-tools-extra/clang-tidy/android/CloexecEpollCreate1Check.cpp
@@ -13,9 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace android {
+namespace clang::tidy::android {
 
 void CloexecEpollCreate1Check::registerMatchers(MatchFinder *Finder) {
   registerMatchersImpl(
@@ -27,6 +25,4 @@ void CloexecEpollCreate1Check::check(const MatchFinder::MatchResult &Result) {
   insertMacroFlag(Result, /*MacroFlag=*/"EPOLL_CLOEXEC", /*ArgPos=*/0);
 }
 
-} // namespace android
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::android

diff  --git a/clang-tools-extra/clang-tidy/android/CloexecEpollCreateCheck.cpp b/clang-tools-extra/clang-tidy/android/CloexecEpollCreateCheck.cpp
index f1d7edfd12055..0a7fe303875b3 100644
--- a/clang-tools-extra/clang-tidy/android/CloexecEpollCreateCheck.cpp
+++ b/clang-tools-extra/clang-tidy/android/CloexecEpollCreateCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace android {
+namespace clang::tidy::android {
 
 void CloexecEpollCreateCheck::registerMatchers(MatchFinder *Finder) {
   registerMatchersImpl(
@@ -30,6 +28,4 @@ void CloexecEpollCreateCheck::check(const MatchFinder::MatchResult &Result) {
               "epoll_create1(EPOLL_CLOEXEC)");
 }
 
-} // namespace android
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::android

diff  --git a/clang-tools-extra/clang-tidy/android/CloexecFopenCheck.cpp b/clang-tools-extra/clang-tidy/android/CloexecFopenCheck.cpp
index dc9908b6a4534..ab165981236ee 100644
--- a/clang-tools-extra/clang-tidy/android/CloexecFopenCheck.cpp
+++ b/clang-tools-extra/clang-tidy/android/CloexecFopenCheck.cpp
@@ -14,9 +14,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace android {
+namespace clang::tidy::android {
 
 void CloexecFopenCheck::registerMatchers(MatchFinder *Finder) {
   auto CharPointerType = hasType(pointerType(pointee(isAnyCharacter())));
@@ -31,6 +29,4 @@ void CloexecFopenCheck::check(const MatchFinder::MatchResult &Result) {
   insertStringFlag(Result, /*Mode=*/'e', /*ArgPos=*/1);
 }
 
-} // namespace android
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::android

diff  --git a/clang-tools-extra/clang-tidy/android/CloexecInotifyInit1Check.cpp b/clang-tools-extra/clang-tidy/android/CloexecInotifyInit1Check.cpp
index f0a0b982b3951..247b3e820cfee 100644
--- a/clang-tools-extra/clang-tidy/android/CloexecInotifyInit1Check.cpp
+++ b/clang-tools-extra/clang-tidy/android/CloexecInotifyInit1Check.cpp
@@ -13,9 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace android {
+namespace clang::tidy::android {
 
 void CloexecInotifyInit1Check::registerMatchers(MatchFinder *Finder) {
   registerMatchersImpl(
@@ -27,6 +25,4 @@ void CloexecInotifyInit1Check::check(const MatchFinder::MatchResult &Result) {
   insertMacroFlag(Result, /*MacroFlag=*/"IN_CLOEXEC", /*ArgPos=*/0);
 }
 
-} // namespace android
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::android

diff  --git a/clang-tools-extra/clang-tidy/android/CloexecInotifyInitCheck.cpp b/clang-tools-extra/clang-tidy/android/CloexecInotifyInitCheck.cpp
index e11cbb8b19872..0e26f9c5838a0 100644
--- a/clang-tools-extra/clang-tidy/android/CloexecInotifyInitCheck.cpp
+++ b/clang-tools-extra/clang-tidy/android/CloexecInotifyInitCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace android {
+namespace clang::tidy::android {
 
 void CloexecInotifyInitCheck::registerMatchers(MatchFinder *Finder) {
   registerMatchersImpl(
@@ -28,6 +26,4 @@ void CloexecInotifyInitCheck::check(const MatchFinder::MatchResult &Result) {
               /*FixMsg=*/"inotify_init1(IN_CLOEXEC)");
 }
 
-} // namespace android
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::android

diff  --git a/clang-tools-extra/clang-tidy/android/CloexecMemfdCreateCheck.cpp b/clang-tools-extra/clang-tidy/android/CloexecMemfdCreateCheck.cpp
index 6fa606b88a88a..4e53d607d81e3 100644
--- a/clang-tools-extra/clang-tidy/android/CloexecMemfdCreateCheck.cpp
+++ b/clang-tools-extra/clang-tidy/android/CloexecMemfdCreateCheck.cpp
@@ -10,9 +10,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace android {
+namespace clang::tidy::android {
 
 void CloexecMemfdCreateCheck::registerMatchers(MatchFinder *Finder) {
   auto CharPointerType = hasType(pointerType(pointee(isAnyCharacter())));
@@ -26,6 +24,4 @@ void CloexecMemfdCreateCheck::check(const MatchFinder::MatchResult &Result) {
   insertMacroFlag(Result, "MFD_CLOEXEC", /*ArgPos=*/1);
 }
 
-} // namespace android
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::android

diff  --git a/clang-tools-extra/clang-tidy/android/CloexecOpenCheck.cpp b/clang-tools-extra/clang-tidy/android/CloexecOpenCheck.cpp
index d0617a336c116..8804bcb41f8f1 100644
--- a/clang-tools-extra/clang-tidy/android/CloexecOpenCheck.cpp
+++ b/clang-tools-extra/clang-tidy/android/CloexecOpenCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace android {
+namespace clang::tidy::android {
 
 void CloexecOpenCheck::registerMatchers(MatchFinder *Finder) {
   auto CharPointerType = hasType(pointerType(pointee(isAnyCharacter())));
@@ -38,6 +36,4 @@ void CloexecOpenCheck::check(const MatchFinder::MatchResult &Result) {
   insertMacroFlag(Result, /*MacroFlag=*/"O_CLOEXEC", ArgPos);
 }
 
-} // namespace android
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::android

diff  --git a/clang-tools-extra/clang-tidy/android/CloexecPipe2Check.cpp b/clang-tools-extra/clang-tidy/android/CloexecPipe2Check.cpp
index 7e3107da3b7cd..773037d9211e8 100644
--- a/clang-tools-extra/clang-tidy/android/CloexecPipe2Check.cpp
+++ b/clang-tools-extra/clang-tidy/android/CloexecPipe2Check.cpp
@@ -13,9 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace android {
+namespace clang::tidy::android {
 
 void CloexecPipe2Check::registerMatchers(MatchFinder *Finder) {
   registerMatchersImpl(Finder,
@@ -28,6 +26,4 @@ void CloexecPipe2Check::check(const MatchFinder::MatchResult &Result) {
   insertMacroFlag(Result, /*MacroFlag=*/"O_CLOEXEC", /*ArgPos=*/1);
 }
 
-} // namespace android
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::android

diff  --git a/clang-tools-extra/clang-tidy/android/CloexecPipeCheck.cpp b/clang-tools-extra/clang-tidy/android/CloexecPipeCheck.cpp
index 94b9450bd5706..8aa0d8f2dea13 100644
--- a/clang-tools-extra/clang-tidy/android/CloexecPipeCheck.cpp
+++ b/clang-tools-extra/clang-tidy/android/CloexecPipeCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace android {
+namespace clang::tidy::android {
 
 void CloexecPipeCheck::registerMatchers(MatchFinder *Finder) {
   registerMatchersImpl(Finder,
@@ -32,6 +30,4 @@ void CloexecPipeCheck::check(const MatchFinder::MatchResult &Result) {
       ReplacementText);
 }
 
-} // namespace android
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::android

diff  --git a/clang-tools-extra/clang-tidy/android/CloexecSocketCheck.cpp b/clang-tools-extra/clang-tidy/android/CloexecSocketCheck.cpp
index dd0f62443a292..9e2e6ca8f668a 100644
--- a/clang-tools-extra/clang-tidy/android/CloexecSocketCheck.cpp
+++ b/clang-tools-extra/clang-tidy/android/CloexecSocketCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace android {
+namespace clang::tidy::android {
 
 void CloexecSocketCheck::registerMatchers(MatchFinder *Finder) {
   registerMatchersImpl(Finder,
@@ -29,6 +27,4 @@ void CloexecSocketCheck::check(const MatchFinder::MatchResult &Result) {
   insertMacroFlag(Result, /*MacroFlag=*/"SOCK_CLOEXEC", /*ArgPos=*/1);
 }
 
-} // namespace android
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::android

diff  --git a/clang-tools-extra/clang-tidy/android/ComparisonInTempFailureRetryCheck.cpp b/clang-tools-extra/clang-tidy/android/ComparisonInTempFailureRetryCheck.cpp
index c7b9896c64f81..9ad56fbb49d5f 100644
--- a/clang-tools-extra/clang-tidy/android/ComparisonInTempFailureRetryCheck.cpp
+++ b/clang-tools-extra/clang-tidy/android/ComparisonInTempFailureRetryCheck.cpp
@@ -14,9 +14,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace android {
+namespace clang::tidy::android {
 
 ComparisonInTempFailureRetryCheck::ComparisonInTempFailureRetryCheck(
     StringRef Name, ClangTidyContext *Context)
@@ -90,6 +88,4 @@ void ComparisonInTempFailureRetryCheck::check(
   // happen, e.g. `TEMP_FAILURE_RETRY(IS_ZERO(foo()))`
 }
 
-} // namespace android
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::android

diff  --git a/clang-tools-extra/clang-tidy/boost/BoostTidyModule.cpp b/clang-tools-extra/clang-tidy/boost/BoostTidyModule.cpp
index 4ab22adec7221..4c5808daa6ae7 100644
--- a/clang-tools-extra/clang-tidy/boost/BoostTidyModule.cpp
+++ b/clang-tools-extra/clang-tidy/boost/BoostTidyModule.cpp
@@ -12,8 +12,7 @@
 #include "UseToStringCheck.h"
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
+namespace clang::tidy {
 namespace boost {
 
 class BoostModule : public ClangTidyModule {
@@ -33,5 +32,4 @@ static ClangTidyModuleRegistry::Add<BoostModule> X("boost-module",
 // and thus register the BoostModule.
 volatile int BoostModuleAnchorSource = 0;
 
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy

diff  --git a/clang-tools-extra/clang-tidy/boost/UseToStringCheck.cpp b/clang-tools-extra/clang-tidy/boost/UseToStringCheck.cpp
index 4e4a0733aa7a9..bcd5def290599 100644
--- a/clang-tools-extra/clang-tidy/boost/UseToStringCheck.cpp
+++ b/clang-tools-extra/clang-tidy/boost/UseToStringCheck.cpp
@@ -10,9 +10,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace boost {
+namespace clang::tidy::boost {
 
 namespace {
 AST_MATCHER(Type, isStrictlyInteger) {
@@ -66,6 +64,4 @@ void UseToStringCheck::check(const MatchFinder::MatchResult &Result) {
       (llvm::Twine("std::to_") + StringType + "(").str());
 }
 
-} // namespace boost
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::boost

diff  --git a/clang-tools-extra/clang-tidy/bugprone/ArgumentCommentCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/ArgumentCommentCheck.cpp
index 76b8cd68fde8b..2a367d737742d 100644
--- a/clang-tools-extra/clang-tidy/bugprone/ArgumentCommentCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/ArgumentCommentCheck.cpp
@@ -16,9 +16,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 namespace {
 AST_MATCHER(Decl, isFromStdNamespaceOrSystemHeader) {
   if (const auto *D = Node.getDeclContext()->getEnclosingNamespaceContext())
@@ -368,6 +366,4 @@ void ArgumentCommentCheck::check(const MatchFinder::MatchResult &Result) {
   }
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/AssertSideEffectCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/AssertSideEffectCheck.cpp
index 74e08ed957d72..600a923b211cf 100644
--- a/clang-tools-extra/clang-tidy/bugprone/AssertSideEffectCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/AssertSideEffectCheck.cpp
@@ -21,9 +21,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 namespace {
 
@@ -134,6 +132,4 @@ void AssertSideEffectCheck::check(const MatchFinder::MatchResult &Result) {
       << AssertMacroName;
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/AssignmentInIfConditionCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/AssignmentInIfConditionCheck.cpp
index 47a82e3c09e25..9e56ee66a064f 100644
--- a/clang-tools-extra/clang-tidy/bugprone/AssignmentInIfConditionCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/AssignmentInIfConditionCheck.cpp
@@ -13,9 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 void AssignmentInIfConditionCheck::registerMatchers(MatchFinder *Finder) {
   Finder->addMatcher(translationUnitDecl(), this);
@@ -76,6 +74,4 @@ void AssignmentInIfConditionCheck::report(const Expr *AssignmentExpr) {
        DiagnosticIDs::Note);
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/BadSignalToKillThreadCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/BadSignalToKillThreadCheck.cpp
index 5b6da9a524816..e1baffda187a0 100644
--- a/clang-tools-extra/clang-tidy/bugprone/BadSignalToKillThreadCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/BadSignalToKillThreadCheck.cpp
@@ -14,9 +14,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 void BadSignalToKillThreadCheck::registerMatchers(MatchFinder *Finder) {
   Finder->addMatcher(
@@ -70,6 +68,4 @@ void BadSignalToKillThreadCheck::registerPPCallbacks(
   PP = Pp;
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/BoolPointerImplicitConversionCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/BoolPointerImplicitConversionCheck.cpp
index 8aae92e405583..09b198d24dc7a 100644
--- a/clang-tools-extra/clang-tidy/bugprone/BoolPointerImplicitConversionCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/BoolPointerImplicitConversionCheck.cpp
@@ -10,9 +10,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 void BoolPointerImplicitConversionCheck::registerMatchers(MatchFinder *Finder) {
   // Look for ifs that have an implicit bool* to bool conversion in the
@@ -84,6 +82,4 @@ void BoolPointerImplicitConversionCheck::check(
   }
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/BranchCloneCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/BranchCloneCheck.cpp
index 5bc35aa6918d9..41b8d32500cdb 100644
--- a/clang-tools-extra/clang-tidy/bugprone/BranchCloneCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/BranchCloneCheck.cpp
@@ -64,9 +64,7 @@ static bool areSwitchBranchesIdentical(const SwitchBranch LHS,
   return true;
 }
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 void BranchCloneCheck::registerMatchers(MatchFinder *Finder) {
   Finder->addMatcher(
@@ -238,6 +236,4 @@ void BranchCloneCheck::check(const MatchFinder::MatchResult &Result) {
   llvm_unreachable("No if statement and no switch statement.");
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/BugproneTidyModule.cpp b/clang-tools-extra/clang-tidy/bugprone/BugproneTidyModule.cpp
index f2842a62c5fe1..a11db603d5ff0 100644
--- a/clang-tools-extra/clang-tidy/bugprone/BugproneTidyModule.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/BugproneTidyModule.cpp
@@ -76,8 +76,7 @@
 #include "UseAfterMoveCheck.h"
 #include "VirtualNearMissCheck.h"
 
-namespace clang {
-namespace tidy {
+namespace clang::tidy {
 namespace bugprone {
 
 class BugproneModule : public ClangTidyModule {
@@ -220,5 +219,4 @@ static ClangTidyModuleRegistry::Add<bugprone::BugproneModule>
 // and thus register the BugproneModule.
 volatile int BugproneModuleAnchorSource = 0;
 
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy

diff  --git a/clang-tools-extra/clang-tidy/bugprone/CopyConstructorInitCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/CopyConstructorInitCheck.cpp
index 5f0cbe0bbed06..6b26b46d032f9 100644
--- a/clang-tools-extra/clang-tidy/bugprone/CopyConstructorInitCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/CopyConstructorInitCheck.cpp
@@ -13,9 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 void CopyConstructorInitCheck::registerMatchers(MatchFinder *Finder) {
   // In the future this might be extended to move constructors?
@@ -112,6 +110,4 @@ void CopyConstructorInitCheck::check(const MatchFinder::MatchResult &Result) {
   Diag << FixItHint::CreateInsertion(FixItLoc, FixItMsg);
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/DanglingHandleCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/DanglingHandleCheck.cpp
index 914430cf38397..11299b9403076 100644
--- a/clang-tools-extra/clang-tidy/bugprone/DanglingHandleCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/DanglingHandleCheck.cpp
@@ -15,9 +15,7 @@
 using namespace clang::ast_matchers;
 using namespace clang::tidy::matchers;
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 namespace {
 
@@ -187,6 +185,4 @@ void DanglingHandleCheck::check(const MatchFinder::MatchResult &Result) {
       << Handle->getQualifiedNameAsString();
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/DynamicStaticInitializersCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/DynamicStaticInitializersCheck.cpp
index 3084248697574..79731ad818c65 100644
--- a/clang-tools-extra/clang-tidy/bugprone/DynamicStaticInitializersCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/DynamicStaticInitializersCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 AST_MATCHER(clang::VarDecl, hasConstantDeclaration) {
   const Expr *Init = Node.getInit();
@@ -62,6 +60,4 @@ void DynamicStaticInitializersCheck::check(const MatchFinder::MatchResult &Resul
     << Var;
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/EasilySwappableParametersCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/EasilySwappableParametersCheck.cpp
index 2c525ec1e5a5e..0e21453234f2f 100644
--- a/clang-tools-extra/clang-tidy/bugprone/EasilySwappableParametersCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/EasilySwappableParametersCheck.cpp
@@ -89,9 +89,7 @@ static constexpr std::size_t
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 using TheCheck = EasilySwappableParametersCheck;
 
@@ -2311,6 +2309,4 @@ void EasilySwappableParametersCheck::check(
   }
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/ExceptionEscapeCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/ExceptionEscapeCheck.cpp
index 85af540b48fbe..276c46ca9fe90 100644
--- a/clang-tools-extra/clang-tidy/bugprone/ExceptionEscapeCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/ExceptionEscapeCheck.cpp
@@ -23,8 +23,7 @@ AST_MATCHER_P(FunctionDecl, isEnabled, llvm::StringSet<>,
 }
 } // namespace
 
-namespace tidy {
-namespace bugprone {
+namespace tidy::bugprone {
 ExceptionEscapeCheck::ExceptionEscapeCheck(StringRef Name,
                                            ClangTidyContext *Context)
     : ClangTidyCheck(Name, Context), RawFunctionsThatShouldNotThrow(Options.get(
@@ -77,6 +76,5 @@ void ExceptionEscapeCheck::check(const MatchFinder::MatchResult &Result) {
         << MatchedDecl;
 }
 
-} // namespace bugprone
-} // namespace tidy
+} // namespace tidy::bugprone
 } // namespace clang

diff  --git a/clang-tools-extra/clang-tidy/bugprone/FoldInitTypeCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/FoldInitTypeCheck.cpp
index d3bcdb23959a6..c7a3032f27c03 100644
--- a/clang-tools-extra/clang-tidy/bugprone/FoldInitTypeCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/FoldInitTypeCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 void FoldInitTypeCheck::registerMatchers(MatchFinder *Finder) {
   // We match functions of interest and bind the iterator and init value types.
@@ -134,6 +132,4 @@ void FoldInitTypeCheck::check(const MatchFinder::MatchResult &Result) {
     doCheck(*Iter2ValueType, *InitType, *Result.Context, *CallNode);
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/ForwardDeclarationNamespaceCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/ForwardDeclarationNamespaceCheck.cpp
index c98a1ab7104fb..ae874210afc1a 100644
--- a/clang-tools-extra/clang-tidy/bugprone/ForwardDeclarationNamespaceCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/ForwardDeclarationNamespaceCheck.cpp
@@ -16,9 +16,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 void ForwardDeclarationNamespaceCheck::registerMatchers(MatchFinder *Finder) {
   // Match all class declarations/definitions *EXCEPT*
@@ -168,6 +166,4 @@ void ForwardDeclarationNamespaceCheck::onEndOfTranslationUnit() {
   }
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/ForwardingReferenceOverloadCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/ForwardingReferenceOverloadCheck.cpp
index 107b11e51c85f..99cb1206b24b4 100644
--- a/clang-tools-extra/clang-tidy/bugprone/ForwardingReferenceOverloadCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/ForwardingReferenceOverloadCheck.cpp
@@ -13,9 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 namespace {
 // Check if the given type is related to std::enable_if.
@@ -145,6 +143,4 @@ void ForwardingReferenceOverloadCheck::check(
   }
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/ImplicitWideningOfMultiplicationResultCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/ImplicitWideningOfMultiplicationResultCheck.cpp
index e09092d842d49..e27012a91c3e5 100644
--- a/clang-tools-extra/clang-tidy/bugprone/ImplicitWideningOfMultiplicationResultCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/ImplicitWideningOfMultiplicationResultCheck.cpp
@@ -21,9 +21,7 @@ AST_MATCHER(ImplicitCastExpr, isPartOfExplicitCast) {
 } // namespace
 } // namespace clang
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 static const Expr *getLHSOfMulBinOp(const Expr *E) {
   assert(E == E->IgnoreParens() && "Already skipped all parens!");
@@ -273,6 +271,4 @@ void ImplicitWideningOfMultiplicationResultCheck::check(
     handlePointerOffsetting(MatchedDecl);
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/InaccurateEraseCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/InaccurateEraseCheck.cpp
index 96fa7ef48348e..164de76d4fa46 100644
--- a/clang-tools-extra/clang-tidy/bugprone/InaccurateEraseCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/InaccurateEraseCheck.cpp
@@ -13,9 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 void InaccurateEraseCheck::registerMatchers(MatchFinder *Finder) {
   const auto EndCall =
@@ -61,6 +59,4 @@ void InaccurateEraseCheck::check(const MatchFinder::MatchResult &Result) {
       << Hint;
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/IncorrectRoundingsCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/IncorrectRoundingsCheck.cpp
index 2f908e44f00c2..beca7aefc88ba 100644
--- a/clang-tools-extra/clang-tidy/bugprone/IncorrectRoundingsCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/IncorrectRoundingsCheck.cpp
@@ -15,9 +15,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 namespace {
 AST_MATCHER(FloatingLiteral, floatHalf) {
@@ -66,6 +64,4 @@ void IncorrectRoundingsCheck::check(const MatchFinder::MatchResult &Result) {
        "consider using lround (#include <cmath>) instead");
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/InfiniteLoopCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/InfiniteLoopCheck.cpp
index 5d4b828233321..e329588290cd4 100644
--- a/clang-tools-extra/clang-tidy/bugprone/InfiniteLoopCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/InfiniteLoopCheck.cpp
@@ -31,8 +31,7 @@ AST_MATCHER(FunctionType, typeHasNoReturnAttr) {
   return Node.getNoReturnAttr();
 }
 } // namespace ast_matchers
-namespace tidy {
-namespace bugprone {
+namespace tidy::bugprone {
 
 static internal::Matcher<Stmt>
 loopEndingStmt(internal::Matcher<Stmt> Internal) {
@@ -329,6 +328,5 @@ void InfiniteLoopCheck::check(const MatchFinder::MatchResult &Result) {
   }
 }
 
-} // namespace bugprone
-} // namespace tidy
+} // namespace tidy::bugprone
 } // namespace clang

diff  --git a/clang-tools-extra/clang-tidy/bugprone/IntegerDivisionCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/IntegerDivisionCheck.cpp
index f68c2f823ba8e..92e0413caceaa 100644
--- a/clang-tools-extra/clang-tidy/bugprone/IntegerDivisionCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/IntegerDivisionCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 void IntegerDivisionCheck::registerMatchers(MatchFinder *Finder) {
   const auto IntType = hasType(isInteger());
@@ -49,6 +47,4 @@ void IntegerDivisionCheck::check(const MatchFinder::MatchResult &Result) {
                               "point context; possible loss of precision");
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/LambdaFunctionNameCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/LambdaFunctionNameCheck.cpp
index ba6f6bae6df1f..2f155820a83e5 100644
--- a/clang-tools-extra/clang-tidy/bugprone/LambdaFunctionNameCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/LambdaFunctionNameCheck.cpp
@@ -15,9 +15,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 namespace {
 
@@ -93,6 +91,4 @@ void LambdaFunctionNameCheck::check(const MatchFinder::MatchResult &Result) {
       << PredefinedExpr::getIdentKindName(E->getIdentKind());
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/MacroParenthesesCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/MacroParenthesesCheck.cpp
index 303119d8ec812..7d89e107a62d2 100644
--- a/clang-tools-extra/clang-tidy/bugprone/MacroParenthesesCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/MacroParenthesesCheck.cpp
@@ -11,9 +11,7 @@
 #include "clang/Lex/PPCallbacks.h"
 #include "clang/Lex/Preprocessor.h"
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 namespace {
 class MacroParenthesesPPCallbacks : public PPCallbacks {
@@ -268,6 +266,4 @@ void MacroParenthesesCheck::registerPPCallbacks(
   PP->addPPCallbacks(std::make_unique<MacroParenthesesPPCallbacks>(PP, this));
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/MacroRepeatedSideEffectsCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/MacroRepeatedSideEffectsCheck.cpp
index dbda14c97e5fc..a64c9b2905ca1 100644
--- a/clang-tools-extra/clang-tidy/bugprone/MacroRepeatedSideEffectsCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/MacroRepeatedSideEffectsCheck.cpp
@@ -13,9 +13,7 @@
 #include "clang/Lex/PPCallbacks.h"
 #include "clang/Lex/Preprocessor.h"
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 namespace {
 class MacroRepeatedPPCallbacks : public PPCallbacks {
@@ -175,6 +173,4 @@ void MacroRepeatedSideEffectsCheck::registerPPCallbacks(
   PP->addPPCallbacks(::std::make_unique<MacroRepeatedPPCallbacks>(*this, *PP));
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/MisplacedOperatorInStrlenInAllocCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/MisplacedOperatorInStrlenInAllocCheck.cpp
index beecfa6be99a0..40e4ab6c8b12a 100644
--- a/clang-tools-extra/clang-tidy/bugprone/MisplacedOperatorInStrlenInAllocCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/MisplacedOperatorInStrlenInAllocCheck.cpp
@@ -13,9 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 void MisplacedOperatorInStrlenInAllocCheck::registerMatchers(
     MatchFinder *Finder) {
@@ -108,6 +106,4 @@ void MisplacedOperatorInStrlenInAllocCheck::check(
       << StrLen->getDirectCallee()->getName() << Hint;
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/MisplacedPointerArithmeticInAllocCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/MisplacedPointerArithmeticInAllocCheck.cpp
index 6208cb5cfc9dc..b9129fa0811c6 100644
--- a/clang-tools-extra/clang-tidy/bugprone/MisplacedPointerArithmeticInAllocCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/MisplacedPointerArithmeticInAllocCheck.cpp
@@ -13,9 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 void MisplacedPointerArithmeticInAllocCheck::registerMatchers(
     MatchFinder *Finder) {
@@ -99,6 +97,4 @@ void MisplacedPointerArithmeticInAllocCheck::check(
       << FixItHint::CreateInsertion(NewRParen, RParen);
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/MisplacedWideningCastCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/MisplacedWideningCastCheck.cpp
index 65fa31e580ff8..bdf388f04a779 100644
--- a/clang-tools-extra/clang-tidy/bugprone/MisplacedWideningCastCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/MisplacedWideningCastCheck.cpp
@@ -13,9 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 MisplacedWideningCastCheck::MisplacedWideningCastCheck(
     StringRef Name, ClangTidyContext *Context)
@@ -226,6 +224,4 @@ void MisplacedWideningCastCheck::check(const MatchFinder::MatchResult &Result) {
       << CalcType << CastType;
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/MoveForwardingReferenceCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/MoveForwardingReferenceCheck.cpp
index f4ff4a9a744bd..96cd1ea29a020 100644
--- a/clang-tools-extra/clang-tidy/bugprone/MoveForwardingReferenceCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/MoveForwardingReferenceCheck.cpp
@@ -14,9 +14,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 static void replaceMoveWithForward(const UnresolvedLookupExpr *Callee,
                                    const ParmVarDecl *ParmVar,
@@ -124,6 +122,4 @@ void MoveForwardingReferenceCheck::check(
                          *Result.Context);
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/MultipleStatementMacroCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/MultipleStatementMacroCheck.cpp
index e57feaf029a83..de05cc0e4f7fb 100644
--- a/clang-tools-extra/clang-tidy/bugprone/MultipleStatementMacroCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/MultipleStatementMacroCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 namespace {
 
@@ -101,6 +99,4 @@ void MultipleStatementMacroCheck::check(
                                       "unconditionally executed");
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/NoEscapeCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/NoEscapeCheck.cpp
index 654e80d9a9c6c..8023e32d53278 100644
--- a/clang-tools-extra/clang-tidy/bugprone/NoEscapeCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/NoEscapeCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 void NoEscapeCheck::registerMatchers(MatchFinder *Finder) {
   Finder->addMatcher(callExpr(callee(functionDecl(hasName("::dispatch_async"))),
@@ -46,6 +44,4 @@ void NoEscapeCheck::check(const MatchFinder::MatchResult &Result) {
   }
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/NotNullTerminatedResultCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/NotNullTerminatedResultCheck.cpp
index 35f12d25e9587..c0c180f6699b3 100644
--- a/clang-tools-extra/clang-tidy/bugprone/NotNullTerminatedResultCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/NotNullTerminatedResultCheck.cpp
@@ -17,9 +17,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 constexpr llvm::StringLiteral FunctionExprName = "FunctionExpr";
 constexpr llvm::StringLiteral CastExprName = "CastExpr";
@@ -1010,6 +1008,4 @@ void NotNullTerminatedResultCheck::xfrmFix(
   lengthArgHandle(LengthHandleKind::Increase, Result, Diag);
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/ParentVirtualCallCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/ParentVirtualCallCheck.cpp
index 02e7ca11f7d60..552034938ae8f 100644
--- a/clang-tools-extra/clang-tidy/bugprone/ParentVirtualCallCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/ParentVirtualCallCheck.cpp
@@ -17,9 +17,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 using BasesVector = llvm::SmallVector<const CXXRecordDecl *, 5>;
 
@@ -147,6 +145,4 @@ void ParentVirtualCallCheck::check(const MatchFinder::MatchResult &Result) {
         getNameAsString(Parents.front()) + "::");
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/PosixReturnCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/PosixReturnCheck.cpp
index 586940ffd795a..378427a1eab00 100644
--- a/clang-tools-extra/clang-tidy/bugprone/PosixReturnCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/PosixReturnCheck.cpp
@@ -14,9 +14,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 static StringRef getFunctionSpelling(const MatchFinder::MatchResult &Result,
                                      const char *BindingStr) {
@@ -82,6 +80,4 @@ void PosixReturnCheck::check(const MatchFinder::MatchResult &Result) {
       << getFunctionSpelling(Result, "binop");
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/RedundantBranchConditionCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/RedundantBranchConditionCheck.cpp
index 3998e2bc1de06..3e04df656a67a 100644
--- a/clang-tools-extra/clang-tidy/bugprone/RedundantBranchConditionCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/RedundantBranchConditionCheck.cpp
@@ -16,9 +16,7 @@
 using namespace clang::ast_matchers;
 using clang::tidy::utils::hasPtrOrReferenceInFunc;
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 static const char CondVarStr[] = "cond_var";
 static const char OuterIfStr[] = "outer_if";
@@ -177,6 +175,4 @@ void RedundantBranchConditionCheck::check(const MatchFinder::MatchResult &Result
   }
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/ReservedIdentifierCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/ReservedIdentifierCheck.cpp
index c6409c0fc2da4..7ecbf74c9cbb6 100644
--- a/clang-tools-extra/clang-tidy/bugprone/ReservedIdentifierCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/ReservedIdentifierCheck.cpp
@@ -20,9 +20,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 static const char DoubleUnderscoreTag[] = "du";
 static const char UnderscoreCapitalTag[] = "uc";
@@ -180,6 +178,4 @@ ReservedIdentifierCheck::getDiagInfo(const NamingCheckId &ID,
                   }};
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/SharedPtrArrayMismatchCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/SharedPtrArrayMismatchCheck.cpp
index b628ebd4ae784..72036aaff158c 100644
--- a/clang-tools-extra/clang-tidy/bugprone/SharedPtrArrayMismatchCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/SharedPtrArrayMismatchCheck.cpp
@@ -10,9 +10,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 SharedPtrArrayMismatchCheck::SharedPtrArrayMismatchCheck(
     StringRef Name, ClangTidyContext *Context)
@@ -26,6 +24,4 @@ SharedPtrArrayMismatchCheck::getSmartPointerClassMatcher() const {
           0, templateArgument(refersToType(qualType().bind(PointerTypeN)))));
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/SignalHandlerCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/SignalHandlerCheck.cpp
index b1684d36d1525..a0b2afdb13103 100644
--- a/clang-tools-extra/clang-tidy/bugprone/SignalHandlerCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/SignalHandlerCheck.cpp
@@ -219,8 +219,7 @@ constexpr llvm::StringLiteral POSIXConformingFunctions[] = {
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
+namespace clang::tidy {
 
 template <>
 struct OptionEnumMapping<
@@ -560,5 +559,4 @@ void SignalHandlerCheck::reportHandlerChain(
 }
 
 } // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy

diff  --git a/clang-tools-extra/clang-tidy/bugprone/SignedCharMisuseCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/SignedCharMisuseCheck.cpp
index ed64429ef4ef3..ea3b8b8e9df4f 100644
--- a/clang-tools-extra/clang-tidy/bugprone/SignedCharMisuseCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/SignedCharMisuseCheck.cpp
@@ -14,9 +14,7 @@
 using namespace clang::ast_matchers;
 using namespace clang::ast_matchers::internal;
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 static constexpr int UnsignedASCIIUpperBound = 127;
 
@@ -168,6 +166,4 @@ void SignedCharMisuseCheck::check(const MatchFinder::MatchResult &Result) {
   }
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/SizeofContainerCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/SizeofContainerCheck.cpp
index d7e69417b39ef..ff8b14913fde2 100644
--- a/clang-tools-extra/clang-tidy/bugprone/SizeofContainerCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/SizeofContainerCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 void SizeofContainerCheck::registerMatchers(MatchFinder *Finder) {
   Finder->addMatcher(
@@ -43,6 +41,4 @@ void SizeofContainerCheck::check(const MatchFinder::MatchResult &Result) {
                                   "container; did you mean .size()?");
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/SizeofExpressionCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/SizeofExpressionCheck.cpp
index 57086af9c7031..62cde11ebb739 100644
--- a/clang-tools-extra/clang-tidy/bugprone/SizeofExpressionCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/SizeofExpressionCheck.cpp
@@ -13,9 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 namespace {
 
@@ -360,6 +358,4 @@ void SizeofExpressionCheck::check(const MatchFinder::MatchResult &Result) {
   }
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/SmartPtrArrayMismatchCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/SmartPtrArrayMismatchCheck.cpp
index 4b89f8291311a..fbdb676be68b0 100644
--- a/clang-tools-extra/clang-tidy/bugprone/SmartPtrArrayMismatchCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/SmartPtrArrayMismatchCheck.cpp
@@ -13,9 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 namespace {
 
@@ -117,6 +115,4 @@ void SmartPtrArrayMismatchCheck::check(const MatchFinder::MatchResult &Result) {
   }
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/SpuriouslyWakeUpFunctionsCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/SpuriouslyWakeUpFunctionsCheck.cpp
index ee45461ed8f2d..ff1d7da7ff402 100644
--- a/clang-tools-extra/clang-tidy/bugprone/SpuriouslyWakeUpFunctionsCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/SpuriouslyWakeUpFunctionsCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 void SpuriouslyWakeUpFunctionsCheck::registerMatchers(MatchFinder *Finder) {
 
@@ -86,6 +84,4 @@ void SpuriouslyWakeUpFunctionsCheck::check(
        "conditional parameter}1")
       << WaitName << (WaitName != "cnd_wait" && WaitName != "cnd_timedwait");
 }
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/StandaloneEmptyCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/StandaloneEmptyCheck.cpp
index 9236bb9009145..67d8e3693fb56 100644
--- a/clang-tools-extra/clang-tidy/bugprone/StandaloneEmptyCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/StandaloneEmptyCheck.cpp
@@ -24,9 +24,7 @@
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/Support/Casting.h"
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 using ast_matchers::BoundNodes;
 using ast_matchers::callee;
@@ -207,6 +205,4 @@ void StandaloneEmptyCheck::check(const MatchFinder::MatchResult &Result) {
   }
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/StringConstructorCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/StringConstructorCheck.cpp
index cf3e17ec413b1..8ae4351ac2830 100644
--- a/clang-tools-extra/clang-tidy/bugprone/StringConstructorCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/StringConstructorCheck.cpp
@@ -14,9 +14,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 namespace {
 AST_MATCHER_P(IntegerLiteral, isBiggerThan, unsigned, N) {
@@ -183,6 +181,4 @@ void StringConstructorCheck::check(const MatchFinder::MatchResult &Result) {
   }
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/StringIntegerAssignmentCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/StringIntegerAssignmentCheck.cpp
index 85d99ee76146f..4f93b3ef779f5 100644
--- a/clang-tools-extra/clang-tidy/bugprone/StringIntegerAssignmentCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/StringIntegerAssignmentCheck.cpp
@@ -13,9 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 void StringIntegerAssignmentCheck::registerMatchers(MatchFinder *Finder) {
   Finder->addMatcher(
@@ -177,6 +175,4 @@ void StringIntegerAssignmentCheck::check(
   }
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/StringLiteralWithEmbeddedNulCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/StringLiteralWithEmbeddedNulCheck.cpp
index 080d4ab67d647..72e680d25cb84 100644
--- a/clang-tools-extra/clang-tidy/bugprone/StringLiteralWithEmbeddedNulCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/StringLiteralWithEmbeddedNulCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 namespace {
 AST_MATCHER(StringLiteral, containsNul) {
@@ -79,6 +77,4 @@ void StringLiteralWithEmbeddedNulCheck::check(
   }
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/StringviewNullptrCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/StringviewNullptrCheck.cpp
index 205f0c4ff9c6f..ea50250f829f0 100644
--- a/clang-tools-extra/clang-tidy/bugprone/StringviewNullptrCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/StringviewNullptrCheck.cpp
@@ -18,9 +18,7 @@
 #include "clang/Tooling/Transformer/Stencil.h"
 #include "llvm/ADT/StringRef.h"
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 using namespace ::clang::ast_matchers;
 using namespace ::clang::transformer;
@@ -302,6 +300,4 @@ StringviewNullptrCheck::StringviewNullptrCheck(StringRef Name,
     : utils::TransformerClangTidyCheck(StringviewNullptrCheckImpl(), Name,
                                        Context) {}
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/SuspiciousEnumUsageCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/SuspiciousEnumUsageCheck.cpp
index 3eda213c59548..3bd8350c83ddf 100644
--- a/clang-tools-extra/clang-tidy/bugprone/SuspiciousEnumUsageCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/SuspiciousEnumUsageCheck.cpp
@@ -13,9 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 static const char DifferentEnumErrorMessage[] =
     "enum values are from 
diff erent enum types";
@@ -208,6 +206,4 @@ void SuspiciousEnumUsageCheck::check(const MatchFinder::MatchResult &Result) {
   checkSuspiciousBitmaskUsage(RhsExpr, EnumDec);
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/SuspiciousIncludeCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/SuspiciousIncludeCheck.cpp
index f3d2e3d7d1ffd..13020bcc503c8 100644
--- a/clang-tools-extra/clang-tidy/bugprone/SuspiciousIncludeCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/SuspiciousIncludeCheck.cpp
@@ -11,9 +11,7 @@
 #include "clang/Lex/Preprocessor.h"
 #include <optional>
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 namespace {
 class SuspiciousIncludePPCallbacks : public PPCallbacks {
@@ -104,6 +102,4 @@ void SuspiciousIncludePPCallbacks::InclusionDirective(
   }
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/SuspiciousMemoryComparisonCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/SuspiciousMemoryComparisonCheck.cpp
index 57d0ff62b4c12..5f68ba6d7eff3 100644
--- a/clang-tools-extra/clang-tidy/bugprone/SuspiciousMemoryComparisonCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/SuspiciousMemoryComparisonCheck.cpp
@@ -13,9 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 static std::optional<uint64_t> tryEvaluateSizeExpr(const Expr *SizeExpr,
                                                    const ASTContext &Ctx) {
@@ -81,6 +79,4 @@ void SuspiciousMemoryComparisonCheck::check(
   }
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/SuspiciousMemsetUsageCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/SuspiciousMemsetUsageCheck.cpp
index 1abe470682329..a488d35ca7448 100644
--- a/clang-tools-extra/clang-tidy/bugprone/SuspiciousMemsetUsageCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/SuspiciousMemsetUsageCheck.cpp
@@ -15,9 +15,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 void SuspiciousMemsetUsageCheck::registerMatchers(MatchFinder *Finder) {
   // Match the standard memset:
@@ -133,6 +131,4 @@ void SuspiciousMemsetUsageCheck::check(const MatchFinder::MatchResult &Result) {
   }
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/SuspiciousMissingCommaCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/SuspiciousMissingCommaCheck.cpp
index 1cd5508ce5578..81c38d07a0c7e 100644
--- a/clang-tools-extra/clang-tidy/bugprone/SuspiciousMissingCommaCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/SuspiciousMissingCommaCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 namespace {
 
@@ -125,6 +123,4 @@ void SuspiciousMissingCommaCheck::check(
        "suspicious string literal, probably missing a comma");
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/SuspiciousReallocUsageCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/SuspiciousReallocUsageCheck.cpp
index 9b78c219fc5a9..8a6dcc3c05995 100644
--- a/clang-tools-extra/clang-tidy/bugprone/SuspiciousReallocUsageCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/SuspiciousReallocUsageCheck.cpp
@@ -103,9 +103,7 @@ class FindAssignToVarBefore
 
 } // namespace
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 void SuspiciousReallocUsageCheck::registerMatchers(MatchFinder *Finder) {
   // void *realloc(void *ptr, size_t size);
@@ -158,6 +156,4 @@ void SuspiciousReallocUsageCheck::check(
       << PtrResultExpr->getSourceRange();
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/SuspiciousSemicolonCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/SuspiciousSemicolonCheck.cpp
index 3874a52e7e20a..92b772dd26d45 100644
--- a/clang-tools-extra/clang-tidy/bugprone/SuspiciousSemicolonCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/SuspiciousSemicolonCheck.cpp
@@ -13,9 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 void SuspiciousSemicolonCheck::registerMatchers(MatchFinder *Finder) {
   Finder->addMatcher(
@@ -73,6 +71,4 @@ void SuspiciousSemicolonCheck::check(const MatchFinder::MatchResult &Result) {
       << FixItHint::CreateRemoval(SourceRange(LocStart, LocEnd));
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/SuspiciousStringCompareCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/SuspiciousStringCompareCheck.cpp
index aec5a4d06bd15..151f24907edd6 100644
--- a/clang-tools-extra/clang-tidy/bugprone/SuspiciousStringCompareCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/SuspiciousStringCompareCheck.cpp
@@ -15,9 +15,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 // Semicolon separated list of known string compare-like functions. The list
 // must ends with a semicolon.
@@ -207,6 +205,4 @@ void SuspiciousStringCompareCheck::check(
   }
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/SwappedArgumentsCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/SwappedArgumentsCheck.cpp
index 247c18516b84c..078aed6911c5f 100644
--- a/clang-tools-extra/clang-tidy/bugprone/SwappedArgumentsCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/SwappedArgumentsCheck.cpp
@@ -14,9 +14,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 void SwappedArgumentsCheck::registerMatchers(MatchFinder *Finder) {
   Finder->addMatcher(callExpr().bind("call"), this);
@@ -96,6 +94,4 @@ void SwappedArgumentsCheck::check(const MatchFinder::MatchResult &Result) {
   }
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/TerminatingContinueCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/TerminatingContinueCheck.cpp
index 65da4c325de4c..e8f63fb7091d7 100644
--- a/clang-tools-extra/clang-tidy/bugprone/TerminatingContinueCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/TerminatingContinueCheck.cpp
@@ -14,9 +14,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 void TerminatingContinueCheck::registerMatchers(MatchFinder *Finder) {
   const auto DoWithFalse =
@@ -44,6 +42,4 @@ void TerminatingContinueCheck::check(const MatchFinder::MatchResult &Result) {
       << tooling::fixit::createReplacement(*ContStmt, "break");
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/ThrowKeywordMissingCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/ThrowKeywordMissingCheck.cpp
index 3f5d875f471dd..64c155c29cf8b 100644
--- a/clang-tools-extra/clang-tidy/bugprone/ThrowKeywordMissingCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/ThrowKeywordMissingCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 void ThrowKeywordMissingCheck::registerMatchers(MatchFinder *Finder) {
   auto CtorInitializerList =
@@ -44,6 +42,4 @@ void ThrowKeywordMissingCheck::check(const MatchFinder::MatchResult &Result) {
       << TemporaryExpr->getType().getBaseTypeIdentifier()->getName();
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/TooSmallLoopVariableCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/TooSmallLoopVariableCheck.cpp
index f5821fe3b6164..3da34fcb64e17 100644
--- a/clang-tools-extra/clang-tidy/bugprone/TooSmallLoopVariableCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/TooSmallLoopVariableCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 static constexpr llvm::StringLiteral LoopName =
     llvm::StringLiteral("forLoopName");
@@ -175,6 +173,4 @@ void TooSmallLoopVariableCheck::check(const MatchFinder::MatchResult &Result) {
         << LoopVarType << UpperBoundType;
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/UncheckedOptionalAccessCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/UncheckedOptionalAccessCheck.cpp
index c425e2bd5eb93..f02eeceabe96a 100644
--- a/clang-tools-extra/clang-tidy/bugprone/UncheckedOptionalAccessCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/UncheckedOptionalAccessCheck.cpp
@@ -24,9 +24,7 @@
 #include <optional>
 #include <vector>
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 using ast_matchers::MatchFinder;
 using dataflow::UncheckedOptionalAccessDiagnoser;
 using dataflow::UncheckedOptionalAccessModel;
@@ -101,6 +99,4 @@ void UncheckedOptionalAccessCheck::check(
       diag(Loc, "unchecked access to optional value");
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/UndefinedMemoryManipulationCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/UndefinedMemoryManipulationCheck.cpp
index 514ee5ab06334..c2631ce9b4b0a 100644
--- a/clang-tools-extra/clang-tidy/bugprone/UndefinedMemoryManipulationCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/UndefinedMemoryManipulationCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 namespace {
 AST_MATCHER(CXXRecordDecl, isNotTriviallyCopyable) {
@@ -65,6 +63,4 @@ void UndefinedMemoryManipulationCheck::check(
   }
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/UndelegatedConstructorCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/UndelegatedConstructorCheck.cpp
index 76a7a5d0e6593..bea447f961892 100644
--- a/clang-tools-extra/clang-tidy/bugprone/UndelegatedConstructorCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/UndelegatedConstructorCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 namespace {
 AST_MATCHER_P(Stmt, ignoringTemporaryExpr,
@@ -75,6 +73,4 @@ void UndelegatedConstructorCheck::check(
                          "A temporary object is created here instead");
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/UnhandledExceptionAtNewCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/UnhandledExceptionAtNewCheck.cpp
index c558b3148c9d5..b160e7259905b 100644
--- a/clang-tools-extra/clang-tidy/bugprone/UnhandledExceptionAtNewCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/UnhandledExceptionAtNewCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 AST_MATCHER_P(CXXTryStmt, hasHandlerFor,
               ast_matchers::internal::Matcher<QualType>, InnerMatcher) {
@@ -73,6 +71,4 @@ void UnhandledExceptionAtNewCheck::check(
          "missing exception handler for allocation failure at 'new'");
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/UnhandledSelfAssignmentCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/UnhandledSelfAssignmentCheck.cpp
index bf4bb750da027..8121a36f80346 100644
--- a/clang-tools-extra/clang-tidy/bugprone/UnhandledSelfAssignmentCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/UnhandledSelfAssignmentCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 UnhandledSelfAssignmentCheck::UnhandledSelfAssignmentCheck(
     StringRef Name, ClangTidyContext *Context)
@@ -107,6 +105,4 @@ void UnhandledSelfAssignmentCheck::check(
        "operator=() does not handle self-assignment properly");
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/UnusedRaiiCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/UnusedRaiiCheck.cpp
index 435c47348c7c0..d96e7524172bd 100644
--- a/clang-tools-extra/clang-tidy/bugprone/UnusedRaiiCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/UnusedRaiiCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 namespace {
 AST_MATCHER(CXXRecordDecl, hasNonTrivialDestructor) {
@@ -96,6 +94,4 @@ void UnusedRaiiCheck::check(const MatchFinder::MatchResult &Result) {
   }
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/UnusedReturnValueCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/UnusedReturnValueCheck.cpp
index 616155dc35c2e..6049569b5f581 100644
--- a/clang-tools-extra/clang-tidy/bugprone/UnusedReturnValueCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/UnusedReturnValueCheck.cpp
@@ -14,9 +14,7 @@
 using namespace clang::ast_matchers;
 using namespace clang::ast_matchers::internal;
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 namespace {
 
@@ -176,6 +174,4 @@ void UnusedReturnValueCheck::check(const MatchFinder::MatchResult &Result) {
   }
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/UseAfterMoveCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/UseAfterMoveCheck.cpp
index f8a8617232316..b7eadb87b4fcd 100644
--- a/clang-tools-extra/clang-tidy/bugprone/UseAfterMoveCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/UseAfterMoveCheck.cpp
@@ -22,10 +22,7 @@
 using namespace clang::ast_matchers;
 using namespace clang::tidy::utils;
 
-
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 namespace {
 
@@ -467,6 +464,4 @@ void UseAfterMoveCheck::check(const MatchFinder::MatchResult &Result) {
     emitDiagnostic(MovingCall, Arg, Use, this, Result.Context);
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/bugprone/VirtualNearMissCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/VirtualNearMissCheck.cpp
index f2aeac2430958..bebdce525e288 100644
--- a/clang-tools-extra/clang-tidy/bugprone/VirtualNearMissCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/VirtualNearMissCheck.cpp
@@ -14,9 +14,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace bugprone {
+namespace clang::tidy::bugprone {
 
 namespace {
 AST_MATCHER(CXXMethodDecl, isStatic) { return Node.isStatic(); }
@@ -267,6 +265,4 @@ void VirtualNearMissCheck::check(const MatchFinder::MatchResult &Result) {
   }
 }
 
-} // namespace bugprone
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::bugprone

diff  --git a/clang-tools-extra/clang-tidy/cert/CERTTidyModule.cpp b/clang-tools-extra/clang-tidy/cert/CERTTidyModule.cpp
index 5686d3edafb06..c3be9d66d090a 100644
--- a/clang-tools-extra/clang-tidy/cert/CERTTidyModule.cpp
+++ b/clang-tools-extra/clang-tidy/cert/CERTTidyModule.cpp
@@ -227,8 +227,7 @@ const llvm::StringRef CertErr33CCheckedFunctions = "::aligned_alloc;"
 
 } // namespace
 
-namespace clang {
-namespace tidy {
+namespace clang::tidy {
 namespace cert {
 
 class CERTModule : public ClangTidyModule {
@@ -341,5 +340,4 @@ static ClangTidyModuleRegistry::Add<cert::CERTModule>
 // and thus register the CERTModule.
 volatile int CERTModuleAnchorSource = 0;
 
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy

diff  --git a/clang-tools-extra/clang-tidy/cert/CommandProcessorCheck.cpp b/clang-tools-extra/clang-tidy/cert/CommandProcessorCheck.cpp
index 131ae9b3ed55f..1c57a8fa8e509 100644
--- a/clang-tools-extra/clang-tidy/cert/CommandProcessorCheck.cpp
+++ b/clang-tools-extra/clang-tidy/cert/CommandProcessorCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace cert {
+namespace clang::tidy::cert {
 
 void CommandProcessorCheck::registerMatchers(MatchFinder *Finder) {
   Finder->addMatcher(
@@ -38,6 +36,4 @@ void CommandProcessorCheck::check(const MatchFinder::MatchResult &Result) {
   diag(E->getExprLoc(), "calling %0 uses a command processor") << Fn;
 }
 
-} // namespace cert
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::cert

diff  --git a/clang-tools-extra/clang-tidy/cert/DefaultOperatorNewAlignmentCheck.cpp b/clang-tools-extra/clang-tidy/cert/DefaultOperatorNewAlignmentCheck.cpp
index 1b0cf899a2999..2a0d0ada42b28 100644
--- a/clang-tools-extra/clang-tidy/cert/DefaultOperatorNewAlignmentCheck.cpp
+++ b/clang-tools-extra/clang-tidy/cert/DefaultOperatorNewAlignmentCheck.cpp
@@ -13,9 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace cert {
+namespace clang::tidy::cert {
 
 void DefaultOperatorNewAlignmentCheck::registerMatchers(MatchFinder *Finder) {
   Finder->addMatcher(
@@ -63,6 +61,4 @@ void DefaultOperatorNewAlignmentCheck::check(
         << (SpecifiedAlignment / CharWidth);
 }
 
-} // namespace cert
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::cert

diff  --git a/clang-tools-extra/clang-tidy/cert/DontModifyStdNamespaceCheck.cpp b/clang-tools-extra/clang-tidy/cert/DontModifyStdNamespaceCheck.cpp
index c63673b91a4fd..bc4970825b4ca 100644
--- a/clang-tools-extra/clang-tidy/cert/DontModifyStdNamespaceCheck.cpp
+++ b/clang-tools-extra/clang-tidy/cert/DontModifyStdNamespaceCheck.cpp
@@ -37,9 +37,7 @@ AST_POLYMORPHIC_MATCHER_P(
 
 } // namespace
 
-namespace clang {
-namespace tidy {
-namespace cert {
+namespace clang::tidy::cert {
 
 void DontModifyStdNamespaceCheck::registerMatchers(MatchFinder *Finder) {
   auto HasStdParent =
@@ -99,9 +97,7 @@ void DontModifyStdNamespaceCheck::registerMatchers(MatchFinder *Finder) {
                          .bind("decl"),
                      this);
 }
-} // namespace cert
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::cert
 
 static const NamespaceDecl *getTopLevelLexicalNamespaceDecl(const Decl *D) {
   const NamespaceDecl *LastNS = nullptr;

diff  --git a/clang-tools-extra/clang-tidy/cert/FloatLoopCounter.cpp b/clang-tools-extra/clang-tidy/cert/FloatLoopCounter.cpp
index b6b3b1944d0ea..a936383759786 100644
--- a/clang-tools-extra/clang-tidy/cert/FloatLoopCounter.cpp
+++ b/clang-tools-extra/clang-tidy/cert/FloatLoopCounter.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace cert {
+namespace clang::tidy::cert {
 
 void FloatLoopCounter::registerMatchers(MatchFinder *Finder) {
   Finder->addMatcher(
@@ -29,6 +27,4 @@ void FloatLoopCounter::check(const MatchFinder::MatchResult &Result) {
                                    "floating-point type");
 }
 
-} // namespace cert
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::cert

diff  --git a/clang-tools-extra/clang-tidy/cert/LimitedRandomnessCheck.cpp b/clang-tools-extra/clang-tidy/cert/LimitedRandomnessCheck.cpp
index 0691787f1a90f..f1d2bcaa916d5 100644
--- a/clang-tools-extra/clang-tidy/cert/LimitedRandomnessCheck.cpp
+++ b/clang-tools-extra/clang-tidy/cert/LimitedRandomnessCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace cert {
+namespace clang::tidy::cert {
 
 void LimitedRandomnessCheck::registerMatchers(MatchFinder *Finder) {
   Finder->addMatcher(callExpr(callee(functionDecl(namedDecl(hasName("::rand")),
@@ -32,6 +30,4 @@ void LimitedRandomnessCheck::check(const MatchFinder::MatchResult &Result) {
   diag(MatchedDecl->getBeginLoc(), "rand() has limited randomness" + Msg);
 }
 
-} // namespace cert
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::cert

diff  --git a/clang-tools-extra/clang-tidy/cert/MutatingCopyCheck.cpp b/clang-tools-extra/clang-tidy/cert/MutatingCopyCheck.cpp
index d4ce995d61b62..a97fd720df86a 100644
--- a/clang-tools-extra/clang-tidy/cert/MutatingCopyCheck.cpp
+++ b/clang-tools-extra/clang-tidy/cert/MutatingCopyCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace cert {
+namespace clang::tidy::cert {
 
 static constexpr llvm::StringLiteral SourceDeclName = "ChangedPVD";
 static constexpr llvm::StringLiteral MutatingOperatorName = "MutatingOp";
@@ -71,6 +69,4 @@ void MutatingCopyCheck::check(const MatchFinder::MatchResult &Result) {
     diag(Assignment->getBeginLoc(), "mutating copied object");
 }
 
-} // namespace cert
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::cert

diff  --git a/clang-tools-extra/clang-tidy/cert/NonTrivialTypesLibcMemoryCallsCheck.cpp b/clang-tools-extra/clang-tidy/cert/NonTrivialTypesLibcMemoryCallsCheck.cpp
index 5c8da5b4cacf7..3fce68275d97f 100644
--- a/clang-tools-extra/clang-tidy/cert/NonTrivialTypesLibcMemoryCallsCheck.cpp
+++ b/clang-tools-extra/clang-tidy/cert/NonTrivialTypesLibcMemoryCallsCheck.cpp
@@ -19,9 +19,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace cert {
+namespace clang::tidy::cert {
 
 namespace {
 AST_MATCHER(CXXRecordDecl, isTriviallyDefaultConstructible) {
@@ -126,6 +124,4 @@ void NonTrivialTypesLibcMemoryCallsCheck::check(
   }
 }
 
-} // namespace cert
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::cert

diff  --git a/clang-tools-extra/clang-tidy/cert/PostfixOperatorCheck.cpp b/clang-tools-extra/clang-tidy/cert/PostfixOperatorCheck.cpp
index 0c4b89632e9dd..8ff63ade7315d 100644
--- a/clang-tools-extra/clang-tidy/cert/PostfixOperatorCheck.cpp
+++ b/clang-tools-extra/clang-tidy/cert/PostfixOperatorCheck.cpp
@@ -13,9 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace cert {
+namespace clang::tidy::cert {
 
 void PostfixOperatorCheck::registerMatchers(MatchFinder *Finder) {
   Finder->addMatcher(functionDecl(hasAnyOverloadedOperatorName("++", "--"),
@@ -79,6 +77,4 @@ void PostfixOperatorCheck::check(const MatchFinder::MatchResult &Result) {
     Diag << FixItHint::CreateInsertion(Location, "const ");
 }
 
-} // namespace cert
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::cert

diff  --git a/clang-tools-extra/clang-tidy/cert/ProperlySeededRandomGeneratorCheck.cpp b/clang-tools-extra/clang-tidy/cert/ProperlySeededRandomGeneratorCheck.cpp
index d35ddd021401b..cf7b36e05dc4f 100644
--- a/clang-tools-extra/clang-tidy/cert/ProperlySeededRandomGeneratorCheck.cpp
+++ b/clang-tools-extra/clang-tidy/cert/ProperlySeededRandomGeneratorCheck.cpp
@@ -13,9 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace cert {
+namespace clang::tidy::cert {
 
 ProperlySeededRandomGeneratorCheck::ProperlySeededRandomGeneratorCheck(
     StringRef Name, ClangTidyContext *Context)
@@ -120,6 +118,4 @@ void ProperlySeededRandomGeneratorCheck::checkSeed(
   }
 }
 
-} // namespace cert
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::cert

diff  --git a/clang-tools-extra/clang-tidy/cert/SetLongJmpCheck.cpp b/clang-tools-extra/clang-tidy/cert/SetLongJmpCheck.cpp
index 99f138087abee..e7d9342bf748f 100644
--- a/clang-tools-extra/clang-tidy/cert/SetLongJmpCheck.cpp
+++ b/clang-tools-extra/clang-tidy/cert/SetLongJmpCheck.cpp
@@ -15,9 +15,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace cert {
+namespace clang::tidy::cert {
 
 namespace {
 const char DiagWording[] =
@@ -64,6 +62,4 @@ void SetLongJmpCheck::check(const MatchFinder::MatchResult &Result) {
   diag(E->getExprLoc(), DiagWording) << cast<NamedDecl>(E->getCalleeDecl());
 }
 
-} // namespace cert
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::cert

diff  --git a/clang-tools-extra/clang-tidy/cert/StaticObjectExceptionCheck.cpp b/clang-tools-extra/clang-tidy/cert/StaticObjectExceptionCheck.cpp
index 61ef166b66c2e..c2a42a78c9e48 100644
--- a/clang-tools-extra/clang-tidy/cert/StaticObjectExceptionCheck.cpp
+++ b/clang-tools-extra/clang-tidy/cert/StaticObjectExceptionCheck.cpp
@@ -13,9 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace cert {
+namespace clang::tidy::cert {
 
 void StaticObjectExceptionCheck::registerMatchers(MatchFinder *Finder) {
   // Match any static or thread_local variable declaration that has an
@@ -55,6 +53,4 @@ void StaticObjectExceptionCheck::check(const MatchFinder::MatchResult &Result) {
   }
 }
 
-} // namespace cert
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::cert

diff  --git a/clang-tools-extra/clang-tidy/cert/StrToNumCheck.cpp b/clang-tools-extra/clang-tidy/cert/StrToNumCheck.cpp
index c7abbe180f606..2caf31b32365e 100644
--- a/clang-tools-extra/clang-tidy/cert/StrToNumCheck.cpp
+++ b/clang-tools-extra/clang-tidy/cert/StrToNumCheck.cpp
@@ -15,9 +15,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace cert {
+namespace clang::tidy::cert {
 
 void StrToNumCheck::registerMatchers(MatchFinder *Finder) {
   // Match any function call to the C standard library string conversion
@@ -229,6 +227,4 @@ void StrToNumCheck::check(const MatchFinder::MatchResult &Result) {
       << classifyReplacement(Conversion);
 }
 
-} // namespace cert
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::cert

diff  --git a/clang-tools-extra/clang-tidy/cert/ThrownExceptionTypeCheck.cpp b/clang-tools-extra/clang-tidy/cert/ThrownExceptionTypeCheck.cpp
index 6b2579bdfdb7d..4452192be2323 100644
--- a/clang-tools-extra/clang-tidy/cert/ThrownExceptionTypeCheck.cpp
+++ b/clang-tools-extra/clang-tidy/cert/ThrownExceptionTypeCheck.cpp
@@ -13,9 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace cert {
+namespace clang::tidy::cert {
 
 void ThrownExceptionTypeCheck::registerMatchers(MatchFinder *Finder) {
   Finder->addMatcher(
@@ -34,6 +32,4 @@ void ThrownExceptionTypeCheck::check(const MatchFinder::MatchResult &Result) {
        "thrown exception type is not nothrow copy constructible");
 }
 
-} // namespace cert
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::cert

diff  --git a/clang-tools-extra/clang-tidy/cert/VariadicFunctionDefCheck.cpp b/clang-tools-extra/clang-tidy/cert/VariadicFunctionDefCheck.cpp
index 25b255f7d7924..aeeedbba56123 100644
--- a/clang-tools-extra/clang-tidy/cert/VariadicFunctionDefCheck.cpp
+++ b/clang-tools-extra/clang-tidy/cert/VariadicFunctionDefCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace cert {
+namespace clang::tidy::cert {
 
 void VariadicFunctionDefCheck::registerMatchers(MatchFinder *Finder) {
   // We only care about function *definitions* that are variadic, and do not
@@ -33,6 +31,4 @@ void VariadicFunctionDefCheck::check(const MatchFinder::MatchResult &Result) {
        "parameter pack or currying instead");
 }
 
-} // namespace cert
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::cert

diff  --git a/clang-tools-extra/clang-tidy/concurrency/ConcurrencyTidyModule.cpp b/clang-tools-extra/clang-tidy/concurrency/ConcurrencyTidyModule.cpp
index 7ae891d463f7c..a88ee46fc4abd 100644
--- a/clang-tools-extra/clang-tidy/concurrency/ConcurrencyTidyModule.cpp
+++ b/clang-tools-extra/clang-tidy/concurrency/ConcurrencyTidyModule.cpp
@@ -12,8 +12,7 @@
 #include "MtUnsafeCheck.h"
 #include "ThreadCanceltypeAsynchronousCheck.h"
 
-namespace clang {
-namespace tidy {
+namespace clang::tidy {
 namespace concurrency {
 
 class ConcurrencyModule : public ClangTidyModule {
@@ -36,5 +35,4 @@ static ClangTidyModuleRegistry::Add<concurrency::ConcurrencyModule>
 // and thus register the ConcurrencyModule.
 volatile int ConcurrencyModuleAnchorSource = 0;
 
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy

diff  --git a/clang-tools-extra/clang-tidy/concurrency/MtUnsafeCheck.cpp b/clang-tools-extra/clang-tidy/concurrency/MtUnsafeCheck.cpp
index b087ad6972e4d..93a19d2ab9aec 100644
--- a/clang-tools-extra/clang-tidy/concurrency/MtUnsafeCheck.cpp
+++ b/clang-tools-extra/clang-tidy/concurrency/MtUnsafeCheck.cpp
@@ -258,8 +258,7 @@ static const clang::StringRef PosixFunctions[] = {
     "::wctomb",
 };
 
-namespace clang {
-namespace tidy {
+namespace clang::tidy {
 
 template <> struct OptionEnumMapping<concurrency::MtUnsafeCheck::FunctionSet> {
   static llvm::ArrayRef<
@@ -312,5 +311,4 @@ void MtUnsafeCheck::check(const MatchFinder::MatchResult &Result) {
 }
 
 } // namespace concurrency
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy

diff  --git a/clang-tools-extra/clang-tidy/concurrency/ThreadCanceltypeAsynchronousCheck.cpp b/clang-tools-extra/clang-tidy/concurrency/ThreadCanceltypeAsynchronousCheck.cpp
index 736fff4c1ed6b..7bd79b274df1e 100644
--- a/clang-tools-extra/clang-tidy/concurrency/ThreadCanceltypeAsynchronousCheck.cpp
+++ b/clang-tools-extra/clang-tidy/concurrency/ThreadCanceltypeAsynchronousCheck.cpp
@@ -13,9 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace concurrency {
+namespace clang::tidy::concurrency {
 
 void ThreadCanceltypeAsynchronousCheck::registerMatchers(MatchFinder *Finder) {
   Finder->addMatcher(
@@ -34,6 +32,4 @@ void ThreadCanceltypeAsynchronousCheck::check(
                                    "be 'PTHREAD_CANCEL_ASYNCHRONOUS'");
 }
 
-} // namespace concurrency
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::concurrency

diff  --git a/clang-tools-extra/clang-tidy/cppcoreguidelines/AvoidConstOrRefDataMembersCheck.cpp b/clang-tools-extra/clang-tidy/cppcoreguidelines/AvoidConstOrRefDataMembersCheck.cpp
index aa530ff9e098c..b22fa94663d58 100644
--- a/clang-tools-extra/clang-tidy/cppcoreguidelines/AvoidConstOrRefDataMembersCheck.cpp
+++ b/clang-tools-extra/clang-tidy/cppcoreguidelines/AvoidConstOrRefDataMembersCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace cppcoreguidelines {
+namespace clang::tidy::cppcoreguidelines {
 namespace {
 
 AST_MATCHER(FieldDecl, isMemberOfLambda) {
@@ -44,6 +42,4 @@ void AvoidConstOrRefDataMembersCheck::check(
         << MatchedDecl << MatchedDecl->getType();
 }
 
-} // namespace cppcoreguidelines
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::cppcoreguidelines

diff  --git a/clang-tools-extra/clang-tidy/cppcoreguidelines/AvoidDoWhileCheck.cpp b/clang-tools-extra/clang-tidy/cppcoreguidelines/AvoidDoWhileCheck.cpp
index 1746b98714946..fd6586506187d 100644
--- a/clang-tools-extra/clang-tidy/cppcoreguidelines/AvoidDoWhileCheck.cpp
+++ b/clang-tools-extra/clang-tidy/cppcoreguidelines/AvoidDoWhileCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace cppcoreguidelines {
+namespace clang::tidy::cppcoreguidelines {
 
 AvoidDoWhileCheck::AvoidDoWhileCheck(StringRef Name, ClangTidyContext *Context)
     : ClangTidyCheck(Name, Context),
@@ -36,6 +34,4 @@ void AvoidDoWhileCheck::check(const MatchFinder::MatchResult &Result) {
   }
 }
 
-} // namespace cppcoreguidelines
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::cppcoreguidelines

diff  --git a/clang-tools-extra/clang-tidy/cppcoreguidelines/AvoidGotoCheck.cpp b/clang-tools-extra/clang-tidy/cppcoreguidelines/AvoidGotoCheck.cpp
index bd0d1ac323137..5e6a6772b34d8 100644
--- a/clang-tools-extra/clang-tidy/cppcoreguidelines/AvoidGotoCheck.cpp
+++ b/clang-tools-extra/clang-tidy/cppcoreguidelines/AvoidGotoCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace cppcoreguidelines {
+namespace clang::tidy::cppcoreguidelines {
 
 namespace {
 AST_MATCHER(GotoStmt, isForwardJumping) {
@@ -46,6 +44,4 @@ void AvoidGotoCheck::check(const MatchFinder::MatchResult &Result) {
   diag(Goto->getLabel()->getBeginLoc(), "label defined here",
        DiagnosticIDs::Note);
 }
-} // namespace cppcoreguidelines
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::cppcoreguidelines

diff  --git a/clang-tools-extra/clang-tidy/cppcoreguidelines/AvoidNonConstGlobalVariablesCheck.cpp b/clang-tools-extra/clang-tidy/cppcoreguidelines/AvoidNonConstGlobalVariablesCheck.cpp
index f8ae76d8456f0..db723b144c140 100644
--- a/clang-tools-extra/clang-tidy/cppcoreguidelines/AvoidNonConstGlobalVariablesCheck.cpp
+++ b/clang-tools-extra/clang-tidy/cppcoreguidelines/AvoidNonConstGlobalVariablesCheck.cpp
@@ -13,9 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace cppcoreguidelines {
+namespace clang::tidy::cppcoreguidelines {
 
 namespace {
 AST_MATCHER(VarDecl, isLocalVarDecl) { return Node.isLocalVarDecl(); }
@@ -66,6 +64,4 @@ void AvoidNonConstGlobalVariablesCheck::check(
   }
 }
 
-} // namespace cppcoreguidelines
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::cppcoreguidelines

diff  --git a/clang-tools-extra/clang-tidy/cppcoreguidelines/AvoidReferenceCoroutineParametersCheck.cpp b/clang-tools-extra/clang-tidy/cppcoreguidelines/AvoidReferenceCoroutineParametersCheck.cpp
index 018aaad9a8d7a..17e09c2083634 100644
--- a/clang-tools-extra/clang-tidy/cppcoreguidelines/AvoidReferenceCoroutineParametersCheck.cpp
+++ b/clang-tools-extra/clang-tidy/cppcoreguidelines/AvoidReferenceCoroutineParametersCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace cppcoreguidelines {
+namespace clang::tidy::cppcoreguidelines {
 
 void AvoidReferenceCoroutineParametersCheck::registerMatchers(
     MatchFinder *Finder) {
@@ -33,6 +31,4 @@ void AvoidReferenceCoroutineParametersCheck::check(
   }
 }
 
-} // namespace cppcoreguidelines
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::cppcoreguidelines

diff  --git a/clang-tools-extra/clang-tidy/cppcoreguidelines/CppCoreGuidelinesTidyModule.cpp b/clang-tools-extra/clang-tidy/cppcoreguidelines/CppCoreGuidelinesTidyModule.cpp
index 13a0cc73c4143..d408682d8fc18 100644
--- a/clang-tools-extra/clang-tidy/cppcoreguidelines/CppCoreGuidelinesTidyModule.cpp
+++ b/clang-tools-extra/clang-tidy/cppcoreguidelines/CppCoreGuidelinesTidyModule.cpp
@@ -40,8 +40,7 @@
 #include "SpecialMemberFunctionsCheck.h"
 #include "VirtualClassDestructorCheck.h"
 
-namespace clang {
-namespace tidy {
+namespace clang::tidy {
 namespace cppcoreguidelines {
 
 /// A module containing checks of the C++ Core Guidelines
@@ -129,5 +128,4 @@ static ClangTidyModuleRegistry::Add<CppCoreGuidelinesModule>
 // and thus register the CppCoreGuidelinesModule.
 volatile int CppCoreGuidelinesModuleAnchorSource = 0;
 
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy

diff  --git a/clang-tools-extra/clang-tidy/cppcoreguidelines/InitVariablesCheck.cpp b/clang-tools-extra/clang-tidy/cppcoreguidelines/InitVariablesCheck.cpp
index 75cc360d3b783..b4543e0d2ae42 100644
--- a/clang-tools-extra/clang-tidy/cppcoreguidelines/InitVariablesCheck.cpp
+++ b/clang-tools-extra/clang-tidy/cppcoreguidelines/InitVariablesCheck.cpp
@@ -16,9 +16,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace cppcoreguidelines {
+namespace clang::tidy::cppcoreguidelines {
 
 namespace {
 AST_MATCHER(VarDecl, isLocalVarDecl) { return Node.isLocalVarDecl(); }
@@ -114,6 +112,4 @@ void InitVariablesCheck::check(const MatchFinder::MatchResult &Result) {
     }
   }
 }
-} // namespace cppcoreguidelines
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::cppcoreguidelines

diff  --git a/clang-tools-extra/clang-tidy/cppcoreguidelines/InterfacesGlobalInitCheck.cpp b/clang-tools-extra/clang-tidy/cppcoreguidelines/InterfacesGlobalInitCheck.cpp
index 30a40cdd0370f..18d297f4161bf 100644
--- a/clang-tools-extra/clang-tidy/cppcoreguidelines/InterfacesGlobalInitCheck.cpp
+++ b/clang-tools-extra/clang-tidy/cppcoreguidelines/InterfacesGlobalInitCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace cppcoreguidelines {
+namespace clang::tidy::cppcoreguidelines {
 
 void InterfacesGlobalInitCheck::registerMatchers(MatchFinder *Finder) {
   const auto GlobalVarDecl =
@@ -54,6 +52,4 @@ void InterfacesGlobalInitCheck::check(const MatchFinder::MatchResult &Result) {
       << Referencee;
 }
 
-} // namespace cppcoreguidelines
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::cppcoreguidelines

diff  --git a/clang-tools-extra/clang-tidy/cppcoreguidelines/MacroUsageCheck.cpp b/clang-tools-extra/clang-tidy/cppcoreguidelines/MacroUsageCheck.cpp
index 94a646c7fca03..0cd4bf6fdfd87 100644
--- a/clang-tools-extra/clang-tidy/cppcoreguidelines/MacroUsageCheck.cpp
+++ b/clang-tools-extra/clang-tidy/cppcoreguidelines/MacroUsageCheck.cpp
@@ -16,9 +16,7 @@
 #include <cctype>
 #include <functional>
 
-namespace clang {
-namespace tidy {
-namespace cppcoreguidelines {
+namespace clang::tidy::cppcoreguidelines {
 
 static bool isCapsOnly(StringRef Name) {
   return llvm::all_of(Name, [](const char C) {
@@ -106,6 +104,4 @@ void MacroUsageCheck::warnNaming(const MacroDirective *MD,
       << MacroName;
 }
 
-} // namespace cppcoreguidelines
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::cppcoreguidelines

diff  --git a/clang-tools-extra/clang-tidy/cppcoreguidelines/NarrowingConversionsCheck.cpp b/clang-tools-extra/clang-tidy/cppcoreguidelines/NarrowingConversionsCheck.cpp
index d73a90197937f..08157603aab89 100644
--- a/clang-tools-extra/clang-tidy/cppcoreguidelines/NarrowingConversionsCheck.cpp
+++ b/clang-tools-extra/clang-tidy/cppcoreguidelines/NarrowingConversionsCheck.cpp
@@ -21,9 +21,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace cppcoreguidelines {
+namespace clang::tidy::cppcoreguidelines {
 
 NarrowingConversionsCheck::NarrowingConversionsCheck(StringRef Name,
                                                      ClangTidyContext *Context)
@@ -594,6 +592,4 @@ void NarrowingConversionsCheck::check(const MatchFinder::MatchResult &Result) {
     return handleImplicitCast(*Result.Context, *Cast);
   llvm_unreachable("must be binary operator or cast expression");
 }
-} // namespace cppcoreguidelines
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::cppcoreguidelines

diff  --git a/clang-tools-extra/clang-tidy/cppcoreguidelines/NoMallocCheck.cpp b/clang-tools-extra/clang-tidy/cppcoreguidelines/NoMallocCheck.cpp
index d7cf6525b1a36..d23238369c4f5 100644
--- a/clang-tools-extra/clang-tidy/cppcoreguidelines/NoMallocCheck.cpp
+++ b/clang-tools-extra/clang-tidy/cppcoreguidelines/NoMallocCheck.cpp
@@ -18,9 +18,7 @@
 using namespace clang::ast_matchers;
 using namespace clang::ast_matchers::internal;
 
-namespace clang {
-namespace tidy {
-namespace cppcoreguidelines {
+namespace clang::tidy::cppcoreguidelines {
 
 void NoMallocCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
   Options.store(Opts, "Allocations", AllocList);
@@ -67,6 +65,4 @@ void NoMallocCheck::check(const MatchFinder::MatchResult &Result) {
       << Recommendation << SourceRange(Call->getBeginLoc(), Call->getEndLoc());
 }
 
-} // namespace cppcoreguidelines
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::cppcoreguidelines

diff  --git a/clang-tools-extra/clang-tidy/cppcoreguidelines/OwningMemoryCheck.cpp b/clang-tools-extra/clang-tidy/cppcoreguidelines/OwningMemoryCheck.cpp
index b93bce2ffcb5a..4c18297e29d87 100644
--- a/clang-tools-extra/clang-tidy/cppcoreguidelines/OwningMemoryCheck.cpp
+++ b/clang-tools-extra/clang-tidy/cppcoreguidelines/OwningMemoryCheck.cpp
@@ -17,9 +17,7 @@
 using namespace clang::ast_matchers;
 using namespace clang::ast_matchers::internal;
 
-namespace clang {
-namespace tidy {
-namespace cppcoreguidelines {
+namespace clang::tidy::cppcoreguidelines {
 
 void OwningMemoryCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
   Options.store(Opts, "LegacyResourceProducers", LegacyResourceProducers);
@@ -370,6 +368,4 @@ bool OwningMemoryCheck::handleOwnerMembers(const BoundNodes &Nodes) {
   return false;
 }
 
-} // namespace cppcoreguidelines
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::cppcoreguidelines

diff  --git a/clang-tools-extra/clang-tidy/cppcoreguidelines/PreferMemberInitializerCheck.cpp b/clang-tools-extra/clang-tidy/cppcoreguidelines/PreferMemberInitializerCheck.cpp
index 16a2a69988546..68697dbff3cfa 100644
--- a/clang-tools-extra/clang-tidy/cppcoreguidelines/PreferMemberInitializerCheck.cpp
+++ b/clang-tools-extra/clang-tidy/cppcoreguidelines/PreferMemberInitializerCheck.cpp
@@ -13,9 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace cppcoreguidelines {
+namespace clang::tidy::cppcoreguidelines {
 
 static bool isControlStatement(const Stmt *S) {
   return isa<IfStmt, SwitchStmt, ForStmt, WhileStmt, DoStmt, ReturnStmt,
@@ -315,6 +313,4 @@ void PreferMemberInitializerCheck::check(
   }
 }
 
-} // namespace cppcoreguidelines
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::cppcoreguidelines

diff  --git a/clang-tools-extra/clang-tidy/cppcoreguidelines/ProBoundsArrayToPointerDecayCheck.cpp b/clang-tools-extra/clang-tidy/cppcoreguidelines/ProBoundsArrayToPointerDecayCheck.cpp
index ba9c64ec16a8d..2dfa9567e6493 100644
--- a/clang-tools-extra/clang-tidy/cppcoreguidelines/ProBoundsArrayToPointerDecayCheck.cpp
+++ b/clang-tools-extra/clang-tidy/cppcoreguidelines/ProBoundsArrayToPointerDecayCheck.cpp
@@ -13,9 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace cppcoreguidelines {
+namespace clang::tidy::cppcoreguidelines {
 
 namespace {
 AST_MATCHER_P(CXXForRangeStmt, hasRangeBeginEndStmt,
@@ -79,6 +77,4 @@ void ProBoundsArrayToPointerDecayCheck::check(
                                   "an explicit cast instead");
 }
 
-} // namespace cppcoreguidelines
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::cppcoreguidelines

diff  --git a/clang-tools-extra/clang-tidy/cppcoreguidelines/ProBoundsConstantArrayIndexCheck.cpp b/clang-tools-extra/clang-tidy/cppcoreguidelines/ProBoundsConstantArrayIndexCheck.cpp
index 8c7ae7326a910..da7e6a3216790 100644
--- a/clang-tools-extra/clang-tidy/cppcoreguidelines/ProBoundsConstantArrayIndexCheck.cpp
+++ b/clang-tools-extra/clang-tidy/cppcoreguidelines/ProBoundsConstantArrayIndexCheck.cpp
@@ -15,9 +15,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace cppcoreguidelines {
+namespace clang::tidy::cppcoreguidelines {
 
 ProBoundsConstantArrayIndexCheck::ProBoundsConstantArrayIndexCheck(
     StringRef Name, ClangTidyContext *Context)
@@ -129,6 +127,4 @@ void ProBoundsConstantArrayIndexCheck::check(
   }
 }
 
-} // namespace cppcoreguidelines
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::cppcoreguidelines

diff  --git a/clang-tools-extra/clang-tidy/cppcoreguidelines/ProBoundsPointerArithmeticCheck.cpp b/clang-tools-extra/clang-tidy/cppcoreguidelines/ProBoundsPointerArithmeticCheck.cpp
index 5b88da658f082..a1494a095f5b6 100644
--- a/clang-tools-extra/clang-tidy/cppcoreguidelines/ProBoundsPointerArithmeticCheck.cpp
+++ b/clang-tools-extra/clang-tidy/cppcoreguidelines/ProBoundsPointerArithmeticCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace cppcoreguidelines {
+namespace clang::tidy::cppcoreguidelines {
 
 void ProBoundsPointerArithmeticCheck::registerMatchers(MatchFinder *Finder) {
   if (!getLangOpts().CPlusPlus)
@@ -56,6 +54,4 @@ void ProBoundsPointerArithmeticCheck::check(
   diag(MatchedExpr->getExprLoc(), "do not use pointer arithmetic");
 }
 
-} // namespace cppcoreguidelines
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::cppcoreguidelines

diff  --git a/clang-tools-extra/clang-tidy/cppcoreguidelines/ProTypeConstCastCheck.cpp b/clang-tools-extra/clang-tidy/cppcoreguidelines/ProTypeConstCastCheck.cpp
index 7d67301eca2aa..ef803ab85fa08 100644
--- a/clang-tools-extra/clang-tidy/cppcoreguidelines/ProTypeConstCastCheck.cpp
+++ b/clang-tools-extra/clang-tidy/cppcoreguidelines/ProTypeConstCastCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace cppcoreguidelines {
+namespace clang::tidy::cppcoreguidelines {
 
 void ProTypeConstCastCheck::registerMatchers(MatchFinder *Finder) {
   Finder->addMatcher(cxxConstCastExpr().bind("cast"), this);
@@ -25,6 +23,4 @@ void ProTypeConstCastCheck::check(const MatchFinder::MatchResult &Result) {
   diag(MatchedCast->getOperatorLoc(), "do not use const_cast");
 }
 
-} // namespace cppcoreguidelines
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::cppcoreguidelines

diff  --git a/clang-tools-extra/clang-tidy/cppcoreguidelines/ProTypeCstyleCastCheck.cpp b/clang-tools-extra/clang-tidy/cppcoreguidelines/ProTypeCstyleCastCheck.cpp
index f172097863b2e..5e255dcaacd26 100644
--- a/clang-tools-extra/clang-tidy/cppcoreguidelines/ProTypeCstyleCastCheck.cpp
+++ b/clang-tools-extra/clang-tidy/cppcoreguidelines/ProTypeCstyleCastCheck.cpp
@@ -13,9 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace cppcoreguidelines {
+namespace clang::tidy::cppcoreguidelines {
 
 static bool needsConstCast(QualType SourceType, QualType DestType) {
   SourceType = SourceType.getNonReferenceType();
@@ -99,6 +97,4 @@ void ProTypeCstyleCastCheck::check(const MatchFinder::MatchResult &Result) {
   }
 }
 
-} // namespace cppcoreguidelines
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::cppcoreguidelines

diff  --git a/clang-tools-extra/clang-tidy/cppcoreguidelines/ProTypeMemberInitCheck.cpp b/clang-tools-extra/clang-tidy/cppcoreguidelines/ProTypeMemberInitCheck.cpp
index 975b51cb3bfc5..07b88d5c49e80 100644
--- a/clang-tools-extra/clang-tidy/cppcoreguidelines/ProTypeMemberInitCheck.cpp
+++ b/clang-tools-extra/clang-tidy/cppcoreguidelines/ProTypeMemberInitCheck.cpp
@@ -20,9 +20,7 @@ using namespace clang::tidy::matchers;
 using llvm::SmallPtrSet;
 using llvm::SmallPtrSetImpl;
 
-namespace clang {
-namespace tidy {
-namespace cppcoreguidelines {
+namespace clang::tidy::cppcoreguidelines {
 
 namespace {
 
@@ -579,6 +577,4 @@ void ProTypeMemberInitCheck::checkUninitializedTrivialType(
       Context.getLangOpts().CPlusPlus11 ? "{}" : " = {}");
 }
 
-} // namespace cppcoreguidelines
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::cppcoreguidelines

diff  --git a/clang-tools-extra/clang-tidy/cppcoreguidelines/ProTypeReinterpretCastCheck.cpp b/clang-tools-extra/clang-tidy/cppcoreguidelines/ProTypeReinterpretCastCheck.cpp
index 66f03783773bc..14456caab612b 100644
--- a/clang-tools-extra/clang-tidy/cppcoreguidelines/ProTypeReinterpretCastCheck.cpp
+++ b/clang-tools-extra/clang-tidy/cppcoreguidelines/ProTypeReinterpretCastCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace cppcoreguidelines {
+namespace clang::tidy::cppcoreguidelines {
 
 void ProTypeReinterpretCastCheck::registerMatchers(MatchFinder *Finder) {
   Finder->addMatcher(cxxReinterpretCastExpr().bind("cast"), this);
@@ -27,6 +25,4 @@ void ProTypeReinterpretCastCheck::check(
   diag(MatchedCast->getOperatorLoc(), "do not use reinterpret_cast");
 }
 
-} // namespace cppcoreguidelines
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::cppcoreguidelines

diff  --git a/clang-tools-extra/clang-tidy/cppcoreguidelines/ProTypeStaticCastDowncastCheck.cpp b/clang-tools-extra/clang-tidy/cppcoreguidelines/ProTypeStaticCastDowncastCheck.cpp
index 0298685102cda..5344d465ad1fa 100644
--- a/clang-tools-extra/clang-tidy/cppcoreguidelines/ProTypeStaticCastDowncastCheck.cpp
+++ b/clang-tools-extra/clang-tidy/cppcoreguidelines/ProTypeStaticCastDowncastCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace cppcoreguidelines {
+namespace clang::tidy::cppcoreguidelines {
 
 void ProTypeStaticCastDowncastCheck::registerMatchers(MatchFinder *Finder) {
   Finder->addMatcher(
@@ -46,6 +44,4 @@ void ProTypeStaticCastDowncastCheck::check(
          "do not use static_cast to downcast from a base to a derived class");
 }
 
-} // namespace cppcoreguidelines
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::cppcoreguidelines

diff  --git a/clang-tools-extra/clang-tidy/cppcoreguidelines/ProTypeUnionAccessCheck.cpp b/clang-tools-extra/clang-tidy/cppcoreguidelines/ProTypeUnionAccessCheck.cpp
index 635041b41a2dd..1ed444e630ec2 100644
--- a/clang-tools-extra/clang-tidy/cppcoreguidelines/ProTypeUnionAccessCheck.cpp
+++ b/clang-tools-extra/clang-tidy/cppcoreguidelines/ProTypeUnionAccessCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace cppcoreguidelines {
+namespace clang::tidy::cppcoreguidelines {
 
 void ProTypeUnionAccessCheck::registerMatchers(MatchFinder *Finder) {
   Finder->addMatcher(
@@ -29,6 +27,4 @@ void ProTypeUnionAccessCheck::check(const MatchFinder::MatchResult &Result) {
        "do not access members of unions; use (boost::)variant instead");
 }
 
-} // namespace cppcoreguidelines
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::cppcoreguidelines

diff  --git a/clang-tools-extra/clang-tidy/cppcoreguidelines/ProTypeVarargCheck.cpp b/clang-tools-extra/clang-tidy/cppcoreguidelines/ProTypeVarargCheck.cpp
index 83924f977d1a6..54c89921a4cba 100644
--- a/clang-tools-extra/clang-tidy/cppcoreguidelines/ProTypeVarargCheck.cpp
+++ b/clang-tools-extra/clang-tidy/cppcoreguidelines/ProTypeVarargCheck.cpp
@@ -17,9 +17,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace cppcoreguidelines {
+namespace clang::tidy::cppcoreguidelines {
 
 const internal::VariadicDynCastAllOfMatcher<Stmt, VAArgExpr> VAArgExpr;
 
@@ -193,6 +191,4 @@ void ProTypeVarargCheck::check(const MatchFinder::MatchResult &Result) {
   }
 }
 
-} // namespace cppcoreguidelines
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::cppcoreguidelines

diff  --git a/clang-tools-extra/clang-tidy/cppcoreguidelines/SlicingCheck.cpp b/clang-tools-extra/clang-tidy/cppcoreguidelines/SlicingCheck.cpp
index 7cc3d749120cf..bc094a2f028d6 100644
--- a/clang-tools-extra/clang-tidy/cppcoreguidelines/SlicingCheck.cpp
+++ b/clang-tools-extra/clang-tidy/cppcoreguidelines/SlicingCheck.cpp
@@ -14,9 +14,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace cppcoreguidelines {
+namespace clang::tidy::cppcoreguidelines {
 
 void SlicingCheck::registerMatchers(MatchFinder *Finder) {
   // When we see:
@@ -131,6 +129,4 @@ void SlicingCheck::check(const MatchFinder::MatchResult &Result) {
   }
 }
 
-} // namespace cppcoreguidelines
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::cppcoreguidelines

diff  --git a/clang-tools-extra/clang-tidy/cppcoreguidelines/SpecialMemberFunctionsCheck.cpp b/clang-tools-extra/clang-tidy/cppcoreguidelines/SpecialMemberFunctionsCheck.cpp
index 823075f6ff18a..9bea2a78fa953 100644
--- a/clang-tools-extra/clang-tidy/cppcoreguidelines/SpecialMemberFunctionsCheck.cpp
+++ b/clang-tools-extra/clang-tidy/cppcoreguidelines/SpecialMemberFunctionsCheck.cpp
@@ -17,9 +17,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace cppcoreguidelines {
+namespace clang::tidy::cppcoreguidelines {
 
 SpecialMemberFunctionsCheck::SpecialMemberFunctionsCheck(
     StringRef Name, ClangTidyContext *Context)
@@ -199,6 +197,4 @@ void SpecialMemberFunctionsCheck::checkForMissingMembers(
   }
 }
 
-} // namespace cppcoreguidelines
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::cppcoreguidelines

diff  --git a/clang-tools-extra/clang-tidy/cppcoreguidelines/VirtualClassDestructorCheck.cpp b/clang-tools-extra/clang-tidy/cppcoreguidelines/VirtualClassDestructorCheck.cpp
index 98b48bd6fb1c2..aa70b3896f16d 100644
--- a/clang-tools-extra/clang-tidy/cppcoreguidelines/VirtualClassDestructorCheck.cpp
+++ b/clang-tools-extra/clang-tidy/cppcoreguidelines/VirtualClassDestructorCheck.cpp
@@ -16,9 +16,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace cppcoreguidelines {
+namespace clang::tidy::cppcoreguidelines {
 
 AST_MATCHER(CXXRecordDecl, hasPublicVirtualOrProtectedNonVirtualDestructor) {
   // We need to call Node.getDestructor() instead of matching a
@@ -218,6 +216,4 @@ void VirtualClassDestructorCheck::check(
       << ProtectedAndVirtual << Fix;
 }
 
-} // namespace cppcoreguidelines
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::cppcoreguidelines

diff  --git a/clang-tools-extra/clang-tidy/darwin/AvoidSpinlockCheck.cpp b/clang-tools-extra/clang-tidy/darwin/AvoidSpinlockCheck.cpp
index 2a52725c19c8d..8864fdb786db5 100644
--- a/clang-tools-extra/clang-tidy/darwin/AvoidSpinlockCheck.cpp
+++ b/clang-tools-extra/clang-tidy/darwin/AvoidSpinlockCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace darwin {
+namespace clang::tidy::darwin {
 
 void AvoidSpinlockCheck::registerMatchers(MatchFinder *Finder) {
   Finder->addMatcher(
@@ -31,6 +29,4 @@ void AvoidSpinlockCheck::check(const MatchFinder::MatchResult &Result) {
        "deprecated OSSpinLock");
 }
 
-}  // namespace darwin
-}  // namespace tidy
-}  // namespace clang
+} // namespace clang::tidy::darwin

diff  --git a/clang-tools-extra/clang-tidy/darwin/DarwinTidyModule.cpp b/clang-tools-extra/clang-tidy/darwin/DarwinTidyModule.cpp
index d11ef1fa01c98..3475deada499d 100644
--- a/clang-tools-extra/clang-tidy/darwin/DarwinTidyModule.cpp
+++ b/clang-tools-extra/clang-tidy/darwin/DarwinTidyModule.cpp
@@ -12,8 +12,7 @@
 #include "AvoidSpinlockCheck.h"
 #include "DispatchOnceNonstaticCheck.h"
 
-namespace clang {
-namespace tidy {
+namespace clang::tidy {
 namespace darwin {
 
 class DarwinModule : public ClangTidyModule {
@@ -36,5 +35,4 @@ static ClangTidyModuleRegistry::Add<darwin::DarwinModule>
 // and thus register the DarwinModule.
 volatile int DarwinModuleAnchorSource = 0;
 
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy

diff  --git a/clang-tools-extra/clang-tidy/darwin/DispatchOnceNonstaticCheck.cpp b/clang-tools-extra/clang-tidy/darwin/DispatchOnceNonstaticCheck.cpp
index dac7f83309714..75d38a9724950 100644
--- a/clang-tools-extra/clang-tidy/darwin/DispatchOnceNonstaticCheck.cpp
+++ b/clang-tools-extra/clang-tidy/darwin/DispatchOnceNonstaticCheck.cpp
@@ -16,9 +16,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace darwin {
+namespace clang::tidy::darwin {
 
 void DispatchOnceNonstaticCheck::registerMatchers(MatchFinder *Finder) {
   // Find variables without static or global storage. VarDecls do not include
@@ -57,6 +55,4 @@ void DispatchOnceNonstaticCheck::check(const MatchFinder::MatchResult &Result) {
   }
 }
 
-} // namespace darwin
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::darwin

diff  --git a/clang-tools-extra/clang-tidy/fuchsia/DefaultArgumentsCallsCheck.cpp b/clang-tools-extra/clang-tidy/fuchsia/DefaultArgumentsCallsCheck.cpp
index fa814b8c29a12..96cd30e0badac 100644
--- a/clang-tools-extra/clang-tidy/fuchsia/DefaultArgumentsCallsCheck.cpp
+++ b/clang-tools-extra/clang-tidy/fuchsia/DefaultArgumentsCallsCheck.cpp
@@ -10,9 +10,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace fuchsia {
+namespace clang::tidy::fuchsia {
 
 void DefaultArgumentsCallsCheck::registerMatchers(MatchFinder *Finder) {
   // Calling a function which uses default arguments is disallowed.
@@ -30,6 +28,4 @@ void DefaultArgumentsCallsCheck::check(const MatchFinder::MatchResult &Result) {
        DiagnosticIDs::Note);
 }
 
-} // namespace fuchsia
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::fuchsia

diff  --git a/clang-tools-extra/clang-tidy/fuchsia/DefaultArgumentsDeclarationsCheck.cpp b/clang-tools-extra/clang-tidy/fuchsia/DefaultArgumentsDeclarationsCheck.cpp
index 273c322edb8b4..05a663bf3d239 100644
--- a/clang-tools-extra/clang-tidy/fuchsia/DefaultArgumentsDeclarationsCheck.cpp
+++ b/clang-tools-extra/clang-tidy/fuchsia/DefaultArgumentsDeclarationsCheck.cpp
@@ -11,9 +11,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace fuchsia {
+namespace clang::tidy::fuchsia {
 
 void DefaultArgumentsDeclarationsCheck::registerMatchers(MatchFinder *Finder) {
   // Declaring default parameters is disallowed.
@@ -50,6 +48,4 @@ void DefaultArgumentsDeclarationsCheck::check(
       << D << FixItHint::CreateRemoval(RemovalRange);
 }
 
-} // namespace fuchsia
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::fuchsia

diff  --git a/clang-tools-extra/clang-tidy/fuchsia/FuchsiaTidyModule.cpp b/clang-tools-extra/clang-tidy/fuchsia/FuchsiaTidyModule.cpp
index 39872fa1c7d04..45a79b75e0937 100644
--- a/clang-tools-extra/clang-tidy/fuchsia/FuchsiaTidyModule.cpp
+++ b/clang-tools-extra/clang-tidy/fuchsia/FuchsiaTidyModule.cpp
@@ -20,8 +20,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
+namespace clang::tidy {
 namespace fuchsia {
 
 /// This module is for Fuchsia-specific checks.
@@ -55,5 +54,4 @@ static ClangTidyModuleRegistry::Add<FuchsiaModule>
 // and thus register the FuchsiaModule.
 volatile int FuchsiaModuleAnchorSource = 0;
 
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy

diff  --git a/clang-tools-extra/clang-tidy/fuchsia/MultipleInheritanceCheck.cpp b/clang-tools-extra/clang-tidy/fuchsia/MultipleInheritanceCheck.cpp
index ae3222a2bd1a4..060f3aebcd81e 100644
--- a/clang-tools-extra/clang-tidy/fuchsia/MultipleInheritanceCheck.cpp
+++ b/clang-tools-extra/clang-tidy/fuchsia/MultipleInheritanceCheck.cpp
@@ -13,9 +13,7 @@
 using namespace clang;
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace fuchsia {
+namespace clang::tidy::fuchsia {
 
 namespace {
 AST_MATCHER(CXXRecordDecl, hasBases) {
@@ -122,6 +120,4 @@ void MultipleInheritanceCheck::check(const MatchFinder::MatchResult &Result) {
   }
 }
 
-}  // namespace fuchsia
-}  // namespace tidy
-}  // namespace clang
+} // namespace clang::tidy::fuchsia

diff  --git a/clang-tools-extra/clang-tidy/fuchsia/OverloadedOperatorCheck.cpp b/clang-tools-extra/clang-tidy/fuchsia/OverloadedOperatorCheck.cpp
index fb77efc357a2b..85864006e4d7b 100644
--- a/clang-tools-extra/clang-tidy/fuchsia/OverloadedOperatorCheck.cpp
+++ b/clang-tools-extra/clang-tidy/fuchsia/OverloadedOperatorCheck.cpp
@@ -10,9 +10,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace fuchsia {
+namespace clang::tidy::fuchsia {
 
 namespace {
 AST_MATCHER(FunctionDecl, isFuchsiaOverloadedOperator) {
@@ -41,6 +39,4 @@ void OverloadedOperatorCheck::check(const MatchFinder::MatchResult &Result) {
     diag(Loc, "overloading %0 is disallowed") << D;
 }
 
-} // namespace fuchsia
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::fuchsia

diff  --git a/clang-tools-extra/clang-tidy/fuchsia/StaticallyConstructedObjectsCheck.cpp b/clang-tools-extra/clang-tidy/fuchsia/StaticallyConstructedObjectsCheck.cpp
index 2ec53746fbab1..ac55d01208b63 100644
--- a/clang-tools-extra/clang-tidy/fuchsia/StaticallyConstructedObjectsCheck.cpp
+++ b/clang-tools-extra/clang-tidy/fuchsia/StaticallyConstructedObjectsCheck.cpp
@@ -10,9 +10,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace fuchsia {
+namespace clang::tidy::fuchsia {
 
 namespace {
 AST_MATCHER(Expr, isConstantInitializer) {
@@ -50,6 +48,4 @@ void StaticallyConstructedObjectsCheck::check(
                            "constexpr constructor instead");
 }
 
-} // namespace fuchsia
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::fuchsia

diff  --git a/clang-tools-extra/clang-tidy/fuchsia/TrailingReturnCheck.cpp b/clang-tools-extra/clang-tidy/fuchsia/TrailingReturnCheck.cpp
index 2902e34fe860f..06e26376340d0 100644
--- a/clang-tools-extra/clang-tidy/fuchsia/TrailingReturnCheck.cpp
+++ b/clang-tools-extra/clang-tidy/fuchsia/TrailingReturnCheck.cpp
@@ -13,9 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace fuchsia {
+namespace clang::tidy::fuchsia {
 
 void TrailingReturnCheck::registerMatchers(MatchFinder *Finder) {
   // Functions that have trailing returns are disallowed, except for those
@@ -36,6 +34,4 @@ void TrailingReturnCheck::check(const MatchFinder::MatchResult &Result) {
          "a trailing return type is disallowed for this function declaration");
 }
 
-} // namespace fuchsia
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::fuchsia

diff  --git a/clang-tools-extra/clang-tidy/fuchsia/VirtualInheritanceCheck.cpp b/clang-tools-extra/clang-tidy/fuchsia/VirtualInheritanceCheck.cpp
index 54a4d73c3fffc..9c367423fdb53 100644
--- a/clang-tools-extra/clang-tidy/fuchsia/VirtualInheritanceCheck.cpp
+++ b/clang-tools-extra/clang-tidy/fuchsia/VirtualInheritanceCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace fuchsia {
+namespace clang::tidy::fuchsia {
 
 namespace {
 AST_MATCHER(CXXRecordDecl, hasDirectVirtualBaseClass) {
@@ -37,6 +35,4 @@ void VirtualInheritanceCheck::check(const MatchFinder::MatchResult &Result) {
     diag(D->getBeginLoc(), "direct virtual inheritance is disallowed");
 }
 
-}  // namespace fuchsia
-}  // namespace tidy
-}  // namespace clang
+} // namespace clang::tidy::fuchsia

diff  --git a/clang-tools-extra/clang-tidy/google/AvoidCStyleCastsCheck.cpp b/clang-tools-extra/clang-tidy/google/AvoidCStyleCastsCheck.cpp
index f74d947e5e714..b7dcaf20169eb 100644
--- a/clang-tools-extra/clang-tidy/google/AvoidCStyleCastsCheck.cpp
+++ b/clang-tools-extra/clang-tidy/google/AvoidCStyleCastsCheck.cpp
@@ -14,10 +14,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace google {
-namespace readability {
+namespace clang::tidy::google::readability {
 
 void AvoidCStyleCastsCheck::registerMatchers(
     ast_matchers::MatchFinder *Finder) {
@@ -258,7 +255,4 @@ void AvoidCStyleCastsCheck::check(const MatchFinder::MatchResult &Result) {
   Diag << "static_cast/const_cast/reinterpret_cast";
 }
 
-} // namespace readability
-} // namespace google
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::google::readability

diff  --git a/clang-tools-extra/clang-tidy/google/AvoidNSObjectNewCheck.cpp b/clang-tools-extra/clang-tidy/google/AvoidNSObjectNewCheck.cpp
index aab07bad81220..adcbf245ef7a3 100644
--- a/clang-tools-extra/clang-tidy/google/AvoidNSObjectNewCheck.cpp
+++ b/clang-tools-extra/clang-tidy/google/AvoidNSObjectNewCheck.cpp
@@ -19,10 +19,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace google {
-namespace objc {
+namespace clang::tidy::google::objc {
 
 static bool isMessageExpressionInsideMacro(const ObjCMessageExpr *Expr) {
   SourceLocation ReceiverLocation = Expr->getReceiverRange().getBegin();
@@ -123,7 +120,4 @@ void AvoidNSObjectNewCheck::check(const MatchFinder::MatchResult &Result) {
   }
 }
 
-} // namespace objc
-} // namespace google
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::google::objc

diff  --git a/clang-tools-extra/clang-tidy/google/AvoidThrowingObjCExceptionCheck.cpp b/clang-tools-extra/clang-tidy/google/AvoidThrowingObjCExceptionCheck.cpp
index 9205125e5ac1f..8346ef2a2a9f1 100644
--- a/clang-tools-extra/clang-tidy/google/AvoidThrowingObjCExceptionCheck.cpp
+++ b/clang-tools-extra/clang-tidy/google/AvoidThrowingObjCExceptionCheck.cpp
@@ -12,10 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace google {
-namespace objc {
+namespace clang::tidy::google::objc {
 
 void AvoidThrowingObjCExceptionCheck::registerMatchers(MatchFinder *Finder) {
 
@@ -57,7 +54,4 @@ void AvoidThrowingObjCExceptionCheck::check(
        "Objective-C errors");
 }
 
-}  // namespace objc
-}  // namespace google
-}  // namespace tidy
-}  // namespace clang
+} // namespace clang::tidy::google::objc

diff  --git a/clang-tools-extra/clang-tidy/google/AvoidUnderscoreInGoogletestNameCheck.cpp b/clang-tools-extra/clang-tidy/google/AvoidUnderscoreInGoogletestNameCheck.cpp
index 783db8c0131b0..8ffcf476457db 100644
--- a/clang-tools-extra/clang-tidy/google/AvoidUnderscoreInGoogletestNameCheck.cpp
+++ b/clang-tools-extra/clang-tidy/google/AvoidUnderscoreInGoogletestNameCheck.cpp
@@ -16,10 +16,7 @@
 #include "clang/Lex/PPCallbacks.h"
 #include "clang/Lex/Preprocessor.h"
 
-namespace clang {
-namespace tidy {
-namespace google {
-namespace readability {
+namespace clang::tidy::google::readability {
 
 constexpr llvm::StringLiteral KDisabledTestPrefix = "DISABLED_";
 
@@ -84,7 +81,4 @@ void AvoidUnderscoreInGoogletestNameCheck::registerPPCallbacks(
       std::make_unique<AvoidUnderscoreInGoogletestNameCallback>(PP, this));
 }
 
-} // namespace readability
-} // namespace google
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::google::readability

diff  --git a/clang-tools-extra/clang-tidy/google/DefaultArgumentsCheck.cpp b/clang-tools-extra/clang-tidy/google/DefaultArgumentsCheck.cpp
index 1ec2924d5c76b..0b14a51c12a8c 100644
--- a/clang-tools-extra/clang-tidy/google/DefaultArgumentsCheck.cpp
+++ b/clang-tools-extra/clang-tidy/google/DefaultArgumentsCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace google {
+namespace clang::tidy::google {
 
 void DefaultArgumentsCheck::registerMatchers(MatchFinder *Finder) {
   Finder->addMatcher(
@@ -30,6 +28,4 @@ void DefaultArgumentsCheck::check(const MatchFinder::MatchResult &Result) {
        "default arguments on virtual or override methods are prohibited");
 }
 
-} // namespace google
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::google

diff  --git a/clang-tools-extra/clang-tidy/google/ExplicitConstructorCheck.cpp b/clang-tools-extra/clang-tidy/google/ExplicitConstructorCheck.cpp
index 59f2dfb50d6b0..f6b7ebca52551 100644
--- a/clang-tools-extra/clang-tidy/google/ExplicitConstructorCheck.cpp
+++ b/clang-tools-extra/clang-tidy/google/ExplicitConstructorCheck.cpp
@@ -14,9 +14,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace google {
+namespace clang::tidy::google {
 
 void ExplicitConstructorCheck::registerMatchers(MatchFinder *Finder) {
   Finder->addMatcher(
@@ -146,6 +144,4 @@ void ExplicitConstructorCheck::check(const MatchFinder::MatchResult &Result) {
       << FixItHint::CreateInsertion(Loc, "explicit ");
 }
 
-} // namespace google
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::google

diff  --git a/clang-tools-extra/clang-tidy/google/ExplicitMakePairCheck.cpp b/clang-tools-extra/clang-tidy/google/ExplicitMakePairCheck.cpp
index e719a426e56f1..d911b58cb8b7e 100644
--- a/clang-tools-extra/clang-tidy/google/ExplicitMakePairCheck.cpp
+++ b/clang-tools-extra/clang-tidy/google/ExplicitMakePairCheck.cpp
@@ -20,9 +20,7 @@ AST_MATCHER(DeclRefExpr, hasExplicitTemplateArgs) {
 }
 } // namespace
 
-namespace tidy {
-namespace google {
-namespace build {
+namespace tidy::google::build {
 
 void ExplicitMakePairCheck::registerMatchers(
     ast_matchers::MatchFinder *Finder) {
@@ -66,7 +64,5 @@ void ExplicitMakePairCheck::check(const MatchFinder::MatchResult &Result) {
   }
 }
 
-} // namespace build
-} // namespace google
-} // namespace tidy
+} // namespace tidy::google::build
 } // namespace clang

diff  --git a/clang-tools-extra/clang-tidy/google/FunctionNamingCheck.cpp b/clang-tools-extra/clang-tidy/google/FunctionNamingCheck.cpp
index cedc3850200f5..e42b4e9a1aeaf 100644
--- a/clang-tools-extra/clang-tidy/google/FunctionNamingCheck.cpp
+++ b/clang-tools-extra/clang-tidy/google/FunctionNamingCheck.cpp
@@ -13,10 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace google {
-namespace objc {
+namespace clang::tidy::google::objc {
 
 namespace {
 
@@ -117,7 +114,4 @@ void FunctionNamingCheck::check(const MatchFinder::MatchResult &Result) {
       << MatchedDecl << IsGlobal << generateFixItHint(MatchedDecl);
 }
 
-} // namespace objc
-} // namespace google
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::google::objc

diff  --git a/clang-tools-extra/clang-tidy/google/GlobalNamesInHeadersCheck.cpp b/clang-tools-extra/clang-tidy/google/GlobalNamesInHeadersCheck.cpp
index ae3738aa691e4..1c2a4e1cd3aea 100644
--- a/clang-tools-extra/clang-tidy/google/GlobalNamesInHeadersCheck.cpp
+++ b/clang-tools-extra/clang-tidy/google/GlobalNamesInHeadersCheck.cpp
@@ -14,10 +14,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace google {
-namespace readability {
+namespace clang::tidy::google::readability {
 
 GlobalNamesInHeadersCheck::GlobalNamesInHeadersCheck(StringRef Name,
                                                      ClangTidyContext *Context)
@@ -74,7 +71,4 @@ void GlobalNamesInHeadersCheck::check(const MatchFinder::MatchResult &Result) {
        "using declarations in the global namespace in headers are prohibited");
 }
 
-} // namespace readability
-} // namespace google
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::google::readability

diff  --git a/clang-tools-extra/clang-tidy/google/GlobalVariableDeclarationCheck.cpp b/clang-tools-extra/clang-tidy/google/GlobalVariableDeclarationCheck.cpp
index 8b718ad97d903..a2a728f3b309e 100644
--- a/clang-tools-extra/clang-tidy/google/GlobalVariableDeclarationCheck.cpp
+++ b/clang-tools-extra/clang-tidy/google/GlobalVariableDeclarationCheck.cpp
@@ -16,10 +16,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace google {
-namespace objc {
+namespace clang::tidy::google::objc {
 
 namespace {
 
@@ -98,7 +95,4 @@ void GlobalVariableDeclarationCheck::check(
   }
 }
 
-}  // namespace objc
-}  // namespace google
-}  // namespace tidy
-}  // namespace clang
+} // namespace clang::tidy::google::objc

diff  --git a/clang-tools-extra/clang-tidy/google/GoogleTidyModule.cpp b/clang-tools-extra/clang-tidy/google/GoogleTidyModule.cpp
index d8fcf3fed94fd..830a37af1accf 100644
--- a/clang-tools-extra/clang-tidy/google/GoogleTidyModule.cpp
+++ b/clang-tools-extra/clang-tidy/google/GoogleTidyModule.cpp
@@ -31,8 +31,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
+namespace clang::tidy {
 namespace google {
 
 class GoogleModule : public ClangTidyModule {
@@ -103,5 +102,4 @@ static ClangTidyModuleRegistry::Add<GoogleModule> X("google-module",
 // and thus register the GoogleModule.
 volatile int GoogleModuleAnchorSource = 0;
 
-}  // namespace tidy
-}  // namespace clang
+} // namespace clang::tidy

diff  --git a/clang-tools-extra/clang-tidy/google/IntegerTypesCheck.cpp b/clang-tools-extra/clang-tidy/google/IntegerTypesCheck.cpp
index e6bda4f6abc37..53c6f5aa7940d 100644
--- a/clang-tools-extra/clang-tidy/google/IntegerTypesCheck.cpp
+++ b/clang-tools-extra/clang-tidy/google/IntegerTypesCheck.cpp
@@ -36,9 +36,7 @@ static Token getTokenAtLoc(SourceLocation Loc,
   return Tok;
 }
 
-namespace tidy {
-namespace google {
-namespace runtime {
+namespace tidy::google::runtime {
 
 IntegerTypesCheck::IntegerTypesCheck(StringRef Name, ClangTidyContext *Context)
     : ClangTidyCheck(Name, Context),
@@ -144,7 +142,5 @@ void IntegerTypesCheck::check(const MatchFinder::MatchResult &Result) {
                                                << Replacement;
 }
 
-} // namespace runtime
-} // namespace google
-} // namespace tidy
+} // namespace tidy::google::runtime
 } // namespace clang

diff  --git a/clang-tools-extra/clang-tidy/google/OverloadedUnaryAndCheck.cpp b/clang-tools-extra/clang-tidy/google/OverloadedUnaryAndCheck.cpp
index 28aa5fafde938..a7536607e533f 100644
--- a/clang-tools-extra/clang-tidy/google/OverloadedUnaryAndCheck.cpp
+++ b/clang-tools-extra/clang-tidy/google/OverloadedUnaryAndCheck.cpp
@@ -13,10 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace google {
-namespace runtime {
+namespace clang::tidy::google::runtime {
 
 void OverloadedUnaryAndCheck::registerMatchers(
     ast_matchers::MatchFinder *Finder) {
@@ -39,7 +36,4 @@ void OverloadedUnaryAndCheck::check(const MatchFinder::MatchResult &Result) {
        "do not overload unary operator&, it is dangerous.");
 }
 
-} // namespace runtime
-} // namespace google
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::google::runtime

diff  --git a/clang-tools-extra/clang-tidy/google/TodoCommentCheck.cpp b/clang-tools-extra/clang-tidy/google/TodoCommentCheck.cpp
index afc7fa40db0ae..adad54aa24ba9 100644
--- a/clang-tools-extra/clang-tidy/google/TodoCommentCheck.cpp
+++ b/clang-tools-extra/clang-tidy/google/TodoCommentCheck.cpp
@@ -11,10 +11,7 @@
 #include "clang/Lex/Preprocessor.h"
 #include <optional>
 
-namespace clang {
-namespace tidy {
-namespace google {
-namespace readability {
+namespace clang::tidy::google::readability {
 
 class TodoCommentCheck::TodoCommentHandler : public CommentHandler {
 public:
@@ -64,7 +61,4 @@ void TodoCommentCheck::registerPPCallbacks(const SourceManager &SM,
   PP->addCommentHandler(Handler.get());
 }
 
-} // namespace readability
-} // namespace google
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::google::readability

diff  --git a/clang-tools-extra/clang-tidy/google/UnnamedNamespaceInHeaderCheck.cpp b/clang-tools-extra/clang-tidy/google/UnnamedNamespaceInHeaderCheck.cpp
index 5037799a90b4e..72de9c1e94b20 100644
--- a/clang-tools-extra/clang-tidy/google/UnnamedNamespaceInHeaderCheck.cpp
+++ b/clang-tools-extra/clang-tidy/google/UnnamedNamespaceInHeaderCheck.cpp
@@ -13,10 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace google {
-namespace build {
+namespace clang::tidy::google::build {
 
 UnnamedNamespaceInHeaderCheck::UnnamedNamespaceInHeaderCheck(
     StringRef Name, ClangTidyContext *Context)
@@ -54,7 +51,4 @@ void UnnamedNamespaceInHeaderCheck::check(
     diag(Loc, "do not use unnamed namespaces in header files");
 }
 
-} // namespace build
-} // namespace google
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::google::build

diff  --git a/clang-tools-extra/clang-tidy/google/UpgradeGoogletestCaseCheck.cpp b/clang-tools-extra/clang-tidy/google/UpgradeGoogletestCaseCheck.cpp
index 36e1b3f92a15a..e7b4f9d6657b6 100644
--- a/clang-tools-extra/clang-tidy/google/UpgradeGoogletestCaseCheck.cpp
+++ b/clang-tools-extra/clang-tidy/google/UpgradeGoogletestCaseCheck.cpp
@@ -15,9 +15,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace google {
+namespace clang::tidy::google {
 
 static const llvm::StringRef RenameCaseToSuiteMessage =
     "Google Test APIs named with 'case' are deprecated; use equivalent APIs "
@@ -350,6 +348,4 @@ void UpgradeGoogletestCaseCheck::check(const MatchFinder::MatchResult &Result) {
   Diag << FixItHint::CreateReplacement(ReplacementRange, ReplacementText);
 }
 
-} // namespace google
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::google

diff  --git a/clang-tools-extra/clang-tidy/google/UsingNamespaceDirectiveCheck.cpp b/clang-tools-extra/clang-tidy/google/UsingNamespaceDirectiveCheck.cpp
index 20011fe70a047..2f4913b2d435a 100644
--- a/clang-tools-extra/clang-tidy/google/UsingNamespaceDirectiveCheck.cpp
+++ b/clang-tools-extra/clang-tidy/google/UsingNamespaceDirectiveCheck.cpp
@@ -13,10 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace google {
-namespace build {
+namespace clang::tidy::google::build {
 
 void UsingNamespaceDirectiveCheck::registerMatchers(
     ast_matchers::MatchFinder *Finder) {
@@ -56,7 +53,4 @@ bool UsingNamespaceDirectiveCheck::isStdLiteralsNamespace(
   return Parent->getName() == "literals" && Parent->getParent() &&
          Parent->getParent()->isStdNamespace();
 }
-} // namespace build
-} // namespace google
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::google::build

diff  --git a/clang-tools-extra/clang-tidy/hicpp/ExceptionBaseclassCheck.cpp b/clang-tools-extra/clang-tidy/hicpp/ExceptionBaseclassCheck.cpp
index 8181942d24838..2b2acfdf5b08e 100644
--- a/clang-tools-extra/clang-tidy/hicpp/ExceptionBaseclassCheck.cpp
+++ b/clang-tools-extra/clang-tidy/hicpp/ExceptionBaseclassCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace hicpp {
+namespace clang::tidy::hicpp {
 
 void ExceptionBaseclassCheck::registerMatchers(MatchFinder *Finder) {
   Finder->addMatcher(
@@ -58,6 +56,4 @@ void ExceptionBaseclassCheck::check(const MatchFinder::MatchResult &Result) {
     diag(TypeDecl->getBeginLoc(), "type defined here", DiagnosticIDs::Note);
 }
 
-} // namespace hicpp
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::hicpp

diff  --git a/clang-tools-extra/clang-tidy/hicpp/HICPPTidyModule.cpp b/clang-tools-extra/clang-tidy/hicpp/HICPPTidyModule.cpp
index 253c3893f0d42..3749796877120 100644
--- a/clang-tools-extra/clang-tidy/hicpp/HICPPTidyModule.cpp
+++ b/clang-tools-extra/clang-tidy/hicpp/HICPPTidyModule.cpp
@@ -41,8 +41,7 @@
 #include "NoAssemblerCheck.h"
 #include "SignedBitwiseCheck.h"
 
-namespace clang {
-namespace tidy {
+namespace clang::tidy {
 namespace hicpp {
 
 class HICPPModule : public ClangTidyModule {
@@ -120,5 +119,4 @@ static ClangTidyModuleRegistry::Add<HICPPModule>
 // and thus register the HICPPModule.
 volatile int HICPPModuleAnchorSource = 0;
 
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy

diff  --git a/clang-tools-extra/clang-tidy/hicpp/MultiwayPathsCoveredCheck.cpp b/clang-tools-extra/clang-tidy/hicpp/MultiwayPathsCoveredCheck.cpp
index 8b99a1058079d..ebd20f29a641c 100644
--- a/clang-tools-extra/clang-tidy/hicpp/MultiwayPathsCoveredCheck.cpp
+++ b/clang-tools-extra/clang-tidy/hicpp/MultiwayPathsCoveredCheck.cpp
@@ -13,9 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace hicpp {
+namespace clang::tidy::hicpp {
 
 void MultiwayPathsCoveredCheck::storeOptions(
     ClangTidyOptions::OptionMap &Opts) {
@@ -174,6 +172,4 @@ void MultiwayPathsCoveredCheck::handleSwitchWithoutDefault(
          CaseCount == 1 ? "switch with only one case; use an if statement"
                         : "potential uncovered code path; add a default label");
 }
-} // namespace hicpp
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::hicpp

diff  --git a/clang-tools-extra/clang-tidy/hicpp/NoAssemblerCheck.cpp b/clang-tools-extra/clang-tidy/hicpp/NoAssemblerCheck.cpp
index af5a1cb0f9768..1dc2463d0fc0a 100644
--- a/clang-tools-extra/clang-tidy/hicpp/NoAssemblerCheck.cpp
+++ b/clang-tools-extra/clang-tidy/hicpp/NoAssemblerCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace hicpp {
+namespace clang::tidy::hicpp {
 
 namespace {
 AST_MATCHER(VarDecl, isAsm) { return Node.hasAttr<clang::AsmLabelAttr>(); }
@@ -44,6 +42,4 @@ void NoAssemblerCheck::check(const MatchFinder::MatchResult &Result) {
   diag(ASMLocation, "do not use inline assembler in safety-critical code");
 }
 
-} // namespace hicpp
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::hicpp

diff  --git a/clang-tools-extra/clang-tidy/hicpp/SignedBitwiseCheck.cpp b/clang-tools-extra/clang-tidy/hicpp/SignedBitwiseCheck.cpp
index 35631bdbf3614..51cc26400f7f3 100644
--- a/clang-tools-extra/clang-tidy/hicpp/SignedBitwiseCheck.cpp
+++ b/clang-tools-extra/clang-tidy/hicpp/SignedBitwiseCheck.cpp
@@ -13,9 +13,7 @@
 using namespace clang::ast_matchers;
 using namespace clang::ast_matchers::internal;
 
-namespace clang {
-namespace tidy {
-namespace hicpp {
+namespace clang::tidy::hicpp {
 
 SignedBitwiseCheck::SignedBitwiseCheck(StringRef Name,
                                        ClangTidyContext *Context)
@@ -100,6 +98,4 @@ void SignedBitwiseCheck::check(const MatchFinder::MatchResult &Result) {
       << IsUnary << SignedOperand->getSourceRange() << OperatorLoc;
 }
 
-} // namespace hicpp
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::hicpp

diff  --git a/clang-tools-extra/clang-tidy/linuxkernel/LinuxKernelTidyModule.cpp b/clang-tools-extra/clang-tidy/linuxkernel/LinuxKernelTidyModule.cpp
index e1615ac3a7ddb..e6d64ff61d261 100644
--- a/clang-tools-extra/clang-tidy/linuxkernel/LinuxKernelTidyModule.cpp
+++ b/clang-tools-extra/clang-tidy/linuxkernel/LinuxKernelTidyModule.cpp
@@ -11,8 +11,7 @@
 #include "../ClangTidyModuleRegistry.h"
 #include "MustCheckErrsCheck.h"
 
-namespace clang {
-namespace tidy {
+namespace clang::tidy {
 namespace linuxkernel {
 
 /// This module is for checks specific to the Linux kernel.
@@ -33,5 +32,4 @@ static ClangTidyModuleRegistry::Add<LinuxKernelModule>
 // and thus register the LinuxKernelModule.
 volatile int LinuxKernelModuleAnchorSource = 0;
 
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy

diff  --git a/clang-tools-extra/clang-tidy/linuxkernel/MustCheckErrsCheck.cpp b/clang-tools-extra/clang-tidy/linuxkernel/MustCheckErrsCheck.cpp
index aa8c99150d3fc..400ec0d4fabed 100644
--- a/clang-tools-extra/clang-tidy/linuxkernel/MustCheckErrsCheck.cpp
+++ b/clang-tools-extra/clang-tidy/linuxkernel/MustCheckErrsCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace linuxkernel {
+namespace clang::tidy::linuxkernel {
 
 void MustCheckErrsCheck::registerMatchers(MatchFinder *Finder) {
   auto ErrFn =
@@ -48,6 +46,4 @@ void MustCheckErrsCheck::check(const MatchFinder::MatchResult &Result) {
   }
 }
 
-} // namespace linuxkernel
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::linuxkernel

diff  --git a/clang-tools-extra/clang-tidy/llvm/HeaderGuardCheck.cpp b/clang-tools-extra/clang-tidy/llvm/HeaderGuardCheck.cpp
index 53c1e3c6b833f..8d35ff56de781 100644
--- a/clang-tools-extra/clang-tidy/llvm/HeaderGuardCheck.cpp
+++ b/clang-tools-extra/clang-tidy/llvm/HeaderGuardCheck.cpp
@@ -10,9 +10,7 @@
 #include "clang/Tooling/Tooling.h"
 #include "llvm/Support/Path.h"
 
-namespace clang {
-namespace tidy {
-namespace llvm_check {
+namespace clang::tidy::llvm_check {
 
 LLVMHeaderGuardCheck::LLVMHeaderGuardCheck(StringRef Name,
                                            ClangTidyContext *Context)
@@ -66,6 +64,4 @@ std::string LLVMHeaderGuardCheck::getHeaderGuard(StringRef Filename,
   return StringRef(Guard).upper();
 }
 
-} // namespace llvm_check
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::llvm_check

diff  --git a/clang-tools-extra/clang-tidy/llvm/IncludeOrderCheck.cpp b/clang-tools-extra/clang-tidy/llvm/IncludeOrderCheck.cpp
index 5cf4064444cce..3bfd6676f4b13 100644
--- a/clang-tools-extra/clang-tidy/llvm/IncludeOrderCheck.cpp
+++ b/clang-tools-extra/clang-tidy/llvm/IncludeOrderCheck.cpp
@@ -14,9 +14,7 @@
 
 #include <map>
 
-namespace clang {
-namespace tidy {
-namespace llvm_check {
+namespace clang::tidy::llvm_check {
 
 namespace {
 class IncludeOrderPPCallbacks : public PPCallbacks {
@@ -183,6 +181,4 @@ void IncludeOrderPPCallbacks::EndOfMainFile() {
   IncludeDirectives.clear();
 }
 
-} // namespace llvm_check
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::llvm_check

diff  --git a/clang-tools-extra/clang-tidy/llvm/LLVMTidyModule.cpp b/clang-tools-extra/clang-tidy/llvm/LLVMTidyModule.cpp
index 7e8bfdcdd4d54..e749163699b34 100644
--- a/clang-tools-extra/clang-tidy/llvm/LLVMTidyModule.cpp
+++ b/clang-tools-extra/clang-tidy/llvm/LLVMTidyModule.cpp
@@ -18,8 +18,7 @@
 #include "PreferRegisterOverUnsignedCheck.h"
 #include "TwineLocalCheck.h"
 
-namespace clang {
-namespace tidy {
+namespace clang::tidy {
 namespace llvm_check {
 
 class LLVMModule : public ClangTidyModule {
@@ -60,5 +59,4 @@ static ClangTidyModuleRegistry::Add<LLVMModule> X("llvm-module",
 // and thus register the LLVMModule.
 volatile int LLVMModuleAnchorSource = 0;
 
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy

diff  --git a/clang-tools-extra/clang-tidy/llvm/PreferIsaOrDynCastInConditionalsCheck.cpp b/clang-tools-extra/clang-tidy/llvm/PreferIsaOrDynCastInConditionalsCheck.cpp
index 201c8d23dd4db..2308d77f4257a 100644
--- a/clang-tools-extra/clang-tidy/llvm/PreferIsaOrDynCastInConditionalsCheck.cpp
+++ b/clang-tools-extra/clang-tidy/llvm/PreferIsaOrDynCastInConditionalsCheck.cpp
@@ -19,8 +19,7 @@ namespace ast_matchers {
 AST_MATCHER(Expr, isMacroID) { return Node.getExprLoc().isMacroID(); }
 } // namespace ast_matchers
 
-namespace tidy {
-namespace llvm_check {
+namespace tidy::llvm_check {
 
 void PreferIsaOrDynCastInConditionalsCheck::registerMatchers(
     MatchFinder *Finder) {
@@ -130,6 +129,5 @@ void PreferIsaOrDynCastInConditionalsCheck::check(
   }
 }
 
-} // namespace llvm_check
-} // namespace tidy
+} // namespace tidy::llvm_check
 } // namespace clang

diff  --git a/clang-tools-extra/clang-tidy/llvm/PreferRegisterOverUnsignedCheck.cpp b/clang-tools-extra/clang-tidy/llvm/PreferRegisterOverUnsignedCheck.cpp
index 6e8cabeb4e64e..5d1955575a5b9 100644
--- a/clang-tools-extra/clang-tidy/llvm/PreferRegisterOverUnsignedCheck.cpp
+++ b/clang-tools-extra/clang-tidy/llvm/PreferRegisterOverUnsignedCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace llvm_check {
+namespace clang::tidy::llvm_check {
 
 void PreferRegisterOverUnsignedCheck::registerMatchers(MatchFinder *Finder) {
   auto RegisterClassMatch = hasType(
@@ -61,6 +59,4 @@ void PreferRegisterOverUnsignedCheck::check(
              NeedsQualification ? "llvm::Register" : "Register");
 }
 
-} // namespace llvm_check
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::llvm_check

diff  --git a/clang-tools-extra/clang-tidy/llvm/TwineLocalCheck.cpp b/clang-tools-extra/clang-tidy/llvm/TwineLocalCheck.cpp
index 907bdcb264bf3..42e53ef6025d6 100644
--- a/clang-tools-extra/clang-tidy/llvm/TwineLocalCheck.cpp
+++ b/clang-tools-extra/clang-tidy/llvm/TwineLocalCheck.cpp
@@ -13,9 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace llvm_check {
+namespace clang::tidy::llvm_check {
 
 void TwineLocalCheck::registerMatchers(MatchFinder *Finder) {
   auto TwineType =
@@ -62,6 +60,4 @@ void TwineLocalCheck::check(const MatchFinder::MatchResult &Result) {
   }
 }
 
-} // namespace llvm_check
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::llvm_check

diff  --git a/clang-tools-extra/clang-tidy/llvmlibc/CalleeNamespaceCheck.cpp b/clang-tools-extra/clang-tidy/llvmlibc/CalleeNamespaceCheck.cpp
index 8f4f5452e9890..98ae857b589fd 100644
--- a/clang-tools-extra/clang-tidy/llvmlibc/CalleeNamespaceCheck.cpp
+++ b/clang-tools-extra/clang-tidy/llvmlibc/CalleeNamespaceCheck.cpp
@@ -14,9 +14,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace llvm_libc {
+namespace clang::tidy::llvm_libc {
 
 // Gets the outermost namespace of a DeclContext, right under the Translation
 // Unit.
@@ -65,6 +63,4 @@ void CalleeNamespaceCheck::check(const MatchFinder::MatchResult &Result) {
        clang::DiagnosticIDs::Note);
 }
 
-} // namespace llvm_libc
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::llvm_libc

diff  --git a/clang-tools-extra/clang-tidy/llvmlibc/ImplementationInNamespaceCheck.cpp b/clang-tools-extra/clang-tidy/llvmlibc/ImplementationInNamespaceCheck.cpp
index 842bf43b2c45c..d05310f09ef77 100644
--- a/clang-tools-extra/clang-tidy/llvmlibc/ImplementationInNamespaceCheck.cpp
+++ b/clang-tools-extra/clang-tidy/llvmlibc/ImplementationInNamespaceCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace llvm_libc {
+namespace clang::tidy::llvm_libc {
 
 const static StringRef RequiredNamespace = "__llvm_libc";
 void ImplementationInNamespaceCheck::registerMatchers(MatchFinder *Finder) {
@@ -43,6 +41,4 @@ void ImplementationInNamespaceCheck::check(
       << RequiredNamespace;
 }
 
-} // namespace llvm_libc
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::llvm_libc

diff  --git a/clang-tools-extra/clang-tidy/llvmlibc/LLVMLibcTidyModule.cpp b/clang-tools-extra/clang-tidy/llvmlibc/LLVMLibcTidyModule.cpp
index 61cfe29536646..670be8b0cc64d 100644
--- a/clang-tools-extra/clang-tidy/llvmlibc/LLVMLibcTidyModule.cpp
+++ b/clang-tools-extra/clang-tidy/llvmlibc/LLVMLibcTidyModule.cpp
@@ -13,8 +13,7 @@
 #include "ImplementationInNamespaceCheck.h"
 #include "RestrictSystemLibcHeadersCheck.h"
 
-namespace clang {
-namespace tidy {
+namespace clang::tidy {
 namespace llvm_libc {
 
 class LLVMLibcModule : public ClangTidyModule {
@@ -39,5 +38,4 @@ static ClangTidyModuleRegistry::Add<LLVMLibcModule>
 // and thus register the LLVMLibcModule.
 volatile int LLVMLibcModuleAnchorSource = 0;
 
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy

diff  --git a/clang-tools-extra/clang-tidy/llvmlibc/RestrictSystemLibcHeadersCheck.cpp b/clang-tools-extra/clang-tidy/llvmlibc/RestrictSystemLibcHeadersCheck.cpp
index 4bbbc5771db86..3451d3474fd90 100644
--- a/clang-tools-extra/clang-tidy/llvmlibc/RestrictSystemLibcHeadersCheck.cpp
+++ b/clang-tools-extra/clang-tidy/llvmlibc/RestrictSystemLibcHeadersCheck.cpp
@@ -16,9 +16,7 @@
 // FixItHint - Hint to check documentation script to mark this check as
 // providing a FixIt.
 
-namespace clang {
-namespace tidy {
-namespace llvm_libc {
+namespace clang::tidy::llvm_libc {
 
 namespace {
 
@@ -66,6 +64,4 @@ void RestrictSystemLibcHeadersCheck::registerPPCallbacks(
       *this, SM, CompilerIncudeDir));
 }
 
-} // namespace llvm_libc
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::llvm_libc

diff  --git a/clang-tools-extra/clang-tidy/misc/ConfusableIdentifierCheck.cpp b/clang-tools-extra/clang-tidy/misc/ConfusableIdentifierCheck.cpp
index 73e28fb2b6342..355e097108030 100644
--- a/clang-tools-extra/clang-tidy/misc/ConfusableIdentifierCheck.cpp
+++ b/clang-tools-extra/clang-tidy/misc/ConfusableIdentifierCheck.cpp
@@ -21,9 +21,7 @@ namespace {
 #include "Confusables.inc"
 } // namespace
 
-namespace clang {
-namespace tidy {
-namespace misc {
+namespace clang::tidy::misc {
 
 ConfusableIdentifierCheck::ConfusableIdentifierCheck(StringRef Name,
                                                      ClangTidyContext *Context)
@@ -169,6 +167,4 @@ void ConfusableIdentifierCheck::registerMatchers(
   Finder->addMatcher(ast_matchers::namedDecl().bind("nameddecl"), this);
 }
 
-} // namespace misc
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::misc

diff  --git a/clang-tools-extra/clang-tidy/misc/ConstCorrectnessCheck.cpp b/clang-tools-extra/clang-tidy/misc/ConstCorrectnessCheck.cpp
index 2ce1dc14c3b0d..b7c2f28d72400 100644
--- a/clang-tools-extra/clang-tidy/misc/ConstCorrectnessCheck.cpp
+++ b/clang-tools-extra/clang-tidy/misc/ConstCorrectnessCheck.cpp
@@ -14,9 +14,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace misc {
+namespace clang::tidy::misc {
 
 namespace {
 // FIXME: This matcher exists in some other code-review as well.
@@ -207,6 +205,4 @@ void ConstCorrectnessCheck::registerScope(const CompoundStmt *LocalScope,
     Analyzer = std::make_unique<ExprMutationAnalyzer>(*LocalScope, *Context);
 }
 
-} // namespace misc
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::misc

diff  --git a/clang-tools-extra/clang-tidy/misc/DefinitionsInHeadersCheck.cpp b/clang-tools-extra/clang-tidy/misc/DefinitionsInHeadersCheck.cpp
index 9a7a7e108b120..c894d7edbf40b 100644
--- a/clang-tools-extra/clang-tidy/misc/DefinitionsInHeadersCheck.cpp
+++ b/clang-tools-extra/clang-tidy/misc/DefinitionsInHeadersCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace misc {
+namespace clang::tidy::misc {
 
 namespace {
 
@@ -160,6 +158,4 @@ void DefinitionsInHeadersCheck::check(const MatchFinder::MatchResult &Result) {
   }
 }
 
-} // namespace misc
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::misc

diff  --git a/clang-tools-extra/clang-tidy/misc/MiscTidyModule.cpp b/clang-tools-extra/clang-tidy/misc/MiscTidyModule.cpp
index ec9973345cc65..2ec61f8912632 100644
--- a/clang-tools-extra/clang-tidy/misc/MiscTidyModule.cpp
+++ b/clang-tools-extra/clang-tidy/misc/MiscTidyModule.cpp
@@ -29,8 +29,7 @@
 #include "UnusedUsingDeclsCheck.h"
 #include "UseAnonymousNamespaceCheck.h"
 
-namespace clang {
-namespace tidy {
+namespace clang::tidy {
 namespace misc {
 
 class MiscModule : public ClangTidyModule {
@@ -84,5 +83,4 @@ static ClangTidyModuleRegistry::Add<misc::MiscModule>
 // and thus register the MiscModule.
 volatile int MiscModuleAnchorSource = 0;
 
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy

diff  --git a/clang-tools-extra/clang-tidy/misc/MisleadingIdentifier.cpp b/clang-tools-extra/clang-tidy/misc/MisleadingIdentifier.cpp
index 4ddb8bacbb521..e1b98b86ecbd6 100644
--- a/clang-tools-extra/clang-tidy/misc/MisleadingIdentifier.cpp
+++ b/clang-tools-extra/clang-tidy/misc/MisleadingIdentifier.cpp
@@ -11,9 +11,7 @@
 #include "clang/Frontend/CompilerInstance.h"
 #include "llvm/Support/ConvertUTF.h"
 
-namespace clang {
-namespace tidy {
-namespace misc {
+namespace clang::tidy::misc {
 
 // See https://www.unicode.org/Public/14.0.0/ucd/extracted/DerivedBidiClass.txt
 static bool isUnassignedAL(llvm::UTF32 CP) {
@@ -161,6 +159,4 @@ void MisleadingIdentifierCheck::registerMatchers(
   Finder->addMatcher(ast_matchers::namedDecl().bind("nameddecl"), this);
 }
 
-} // namespace misc
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::misc

diff  --git a/clang-tools-extra/clang-tidy/misc/MisplacedConstCheck.cpp b/clang-tools-extra/clang-tidy/misc/MisplacedConstCheck.cpp
index 62df0884689f0..4aaf64c9c5361 100644
--- a/clang-tools-extra/clang-tidy/misc/MisplacedConstCheck.cpp
+++ b/clang-tools-extra/clang-tidy/misc/MisplacedConstCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace misc {
+namespace clang::tidy::misc {
 
 void MisplacedConstCheck::registerMatchers(MatchFinder *Finder) {
   auto NonConstAndNonFunctionPointerType = hasType(pointerType(unless(
@@ -74,6 +72,4 @@ void MisplacedConstCheck::check(const MatchFinder::MatchResult &Result) {
   diag(AliasLoc, "%0 declared here", DiagnosticIDs::Note) << AliasType;
 }
 
-} // namespace misc
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::misc

diff  --git a/clang-tools-extra/clang-tidy/misc/NewDeleteOverloadsCheck.cpp b/clang-tools-extra/clang-tidy/misc/NewDeleteOverloadsCheck.cpp
index 3f5d59718be5c..e772bcc9ed771 100644
--- a/clang-tools-extra/clang-tidy/misc/NewDeleteOverloadsCheck.cpp
+++ b/clang-tools-extra/clang-tidy/misc/NewDeleteOverloadsCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace misc {
+namespace clang::tidy::misc {
 
 namespace {
 
@@ -204,6 +202,4 @@ void NewDeleteOverloadsCheck::onEndOfTranslationUnit() {
         << FD << getOperatorName(getCorrespondingOverload(FD));
 }
 
-} // namespace misc
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::misc

diff  --git a/clang-tools-extra/clang-tidy/misc/NoRecursionCheck.cpp b/clang-tools-extra/clang-tidy/misc/NoRecursionCheck.cpp
index 3cd019d0c386b..2250bba4db669 100644
--- a/clang-tools-extra/clang-tidy/misc/NoRecursionCheck.cpp
+++ b/clang-tools-extra/clang-tidy/misc/NoRecursionCheck.cpp
@@ -15,9 +15,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace misc {
+namespace clang::tidy::misc {
 
 namespace {
 
@@ -270,6 +268,4 @@ void NoRecursionCheck::check(const MatchFinder::MatchResult &Result) {
   }
 }
 
-} // namespace misc
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::misc

diff  --git a/clang-tools-extra/clang-tidy/misc/NonCopyableObjects.cpp b/clang-tools-extra/clang-tidy/misc/NonCopyableObjects.cpp
index 53cc27344c017..4c415a7fd23d7 100644
--- a/clang-tools-extra/clang-tidy/misc/NonCopyableObjects.cpp
+++ b/clang-tools-extra/clang-tidy/misc/NonCopyableObjects.cpp
@@ -13,9 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace misc {
+namespace clang::tidy::misc {
 
 void NonCopyableObjectsCheck::registerMatchers(MatchFinder *Finder) {
   // There are two ways to get into trouble with objects like FILE *:
@@ -67,7 +65,4 @@ void NonCopyableObjectsCheck::check(const MatchFinder::MatchResult &Result) {
         << BD;
 }
 
-} // namespace misc
-} // namespace tidy
-} // namespace clang
-
+} // namespace clang::tidy::misc

diff  --git a/clang-tools-extra/clang-tidy/misc/NonPrivateMemberVariablesInClassesCheck.cpp b/clang-tools-extra/clang-tidy/misc/NonPrivateMemberVariablesInClassesCheck.cpp
index ed736d111762e..9d7d9d1f865ba 100644
--- a/clang-tools-extra/clang-tidy/misc/NonPrivateMemberVariablesInClassesCheck.cpp
+++ b/clang-tools-extra/clang-tidy/misc/NonPrivateMemberVariablesInClassesCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace misc {
+namespace clang::tidy::misc {
 
 namespace {
 
@@ -92,6 +90,4 @@ void NonPrivateMemberVariablesInClassesCheck::check(
       << Field << Field->getAccess();
 }
 
-} // namespace misc
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::misc

diff  --git a/clang-tools-extra/clang-tidy/misc/RedundantExpressionCheck.cpp b/clang-tools-extra/clang-tidy/misc/RedundantExpressionCheck.cpp
index 40f5b134a37f7..b5028074f017c 100644
--- a/clang-tools-extra/clang-tidy/misc/RedundantExpressionCheck.cpp
+++ b/clang-tools-extra/clang-tidy/misc/RedundantExpressionCheck.cpp
@@ -32,9 +32,7 @@
 using namespace clang::ast_matchers;
 using namespace clang::tidy::matchers;
 
-namespace clang {
-namespace tidy {
-namespace misc {
+namespace clang::tidy::misc {
 namespace {
 using llvm::APSInt;
 
@@ -1357,6 +1355,4 @@ void RedundantExpressionCheck::check(const MatchFinder::MatchResult &Result) {
   checkRelationalExpr(Result);
 }
 
-} // namespace misc
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::misc

diff  --git a/clang-tools-extra/clang-tidy/misc/StaticAssertCheck.cpp b/clang-tools-extra/clang-tidy/misc/StaticAssertCheck.cpp
index 6203e19edce3c..a2fba6760a916 100644
--- a/clang-tools-extra/clang-tidy/misc/StaticAssertCheck.cpp
+++ b/clang-tools-extra/clang-tidy/misc/StaticAssertCheck.cpp
@@ -20,9 +20,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace misc {
+namespace clang::tidy::misc {
 
 StaticAssertCheck::StaticAssertCheck(StringRef Name, ClangTidyContext *Context)
     : ClangTidyCheck(Name, Context) {}
@@ -167,6 +165,4 @@ SourceLocation StaticAssertCheck::getLastParenLoc(const ASTContext *ASTCtx,
   return Token.getLocation();
 }
 
-} // namespace misc
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::misc

diff  --git a/clang-tools-extra/clang-tidy/misc/ThrowByValueCatchByReferenceCheck.cpp b/clang-tools-extra/clang-tidy/misc/ThrowByValueCatchByReferenceCheck.cpp
index 37a81da557ea6..abe7bed9df983 100644
--- a/clang-tools-extra/clang-tidy/misc/ThrowByValueCatchByReferenceCheck.cpp
+++ b/clang-tools-extra/clang-tidy/misc/ThrowByValueCatchByReferenceCheck.cpp
@@ -13,9 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace misc {
+namespace clang::tidy::misc {
 
 ThrowByValueCatchByReferenceCheck::ThrowByValueCatchByReferenceCheck(
     StringRef Name, ClangTidyContext *Context)
@@ -170,6 +168,4 @@ void ThrowByValueCatchByReferenceCheck::diagnoseCatchLocations(
   }
 }
 
-} // namespace misc
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::misc

diff  --git a/clang-tools-extra/clang-tidy/misc/UnconventionalAssignOperatorCheck.cpp b/clang-tools-extra/clang-tidy/misc/UnconventionalAssignOperatorCheck.cpp
index 12ba5d9997fb1..42c4b6edb6d20 100644
--- a/clang-tools-extra/clang-tidy/misc/UnconventionalAssignOperatorCheck.cpp
+++ b/clang-tools-extra/clang-tidy/misc/UnconventionalAssignOperatorCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace misc {
+namespace clang::tidy::misc {
 
 void UnconventionalAssignOperatorCheck::registerMatchers(
     ast_matchers::MatchFinder *Finder) {
@@ -89,6 +87,4 @@ void UnconventionalAssignOperatorCheck::check(
   }
 }
 
-} // namespace misc
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::misc

diff  --git a/clang-tools-extra/clang-tidy/misc/UniqueptrResetReleaseCheck.cpp b/clang-tools-extra/clang-tidy/misc/UniqueptrResetReleaseCheck.cpp
index 7ffbaa44af272..0e24b47f5055f 100644
--- a/clang-tools-extra/clang-tidy/misc/UniqueptrResetReleaseCheck.cpp
+++ b/clang-tools-extra/clang-tidy/misc/UniqueptrResetReleaseCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace misc {
+namespace clang::tidy::misc {
 
 UniqueptrResetReleaseCheck::UniqueptrResetReleaseCheck(
     StringRef Name, ClangTidyContext *Context)
@@ -148,6 +146,4 @@ void UniqueptrResetReleaseCheck::check(const MatchFinder::MatchResult &Result) {
         Result.SourceManager->getFileID(ResetMember->getBeginLoc()),
         "<utility>");
 }
-} // namespace misc
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::misc

diff  --git a/clang-tools-extra/clang-tidy/misc/UnusedAliasDeclsCheck.cpp b/clang-tools-extra/clang-tidy/misc/UnusedAliasDeclsCheck.cpp
index bebf83102881b..2dfaca19a8981 100644
--- a/clang-tools-extra/clang-tidy/misc/UnusedAliasDeclsCheck.cpp
+++ b/clang-tools-extra/clang-tidy/misc/UnusedAliasDeclsCheck.cpp
@@ -13,9 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace misc {
+namespace clang::tidy::misc {
 
 void UnusedAliasDeclsCheck::registerMatchers(MatchFinder *Finder) {
   // We cannot do anything about headers (yet), as the alias declarations
@@ -53,6 +51,4 @@ void UnusedAliasDeclsCheck::onEndOfTranslationUnit() {
   }
 }
 
-} // namespace misc
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::misc

diff  --git a/clang-tools-extra/clang-tidy/misc/UnusedParametersCheck.cpp b/clang-tools-extra/clang-tidy/misc/UnusedParametersCheck.cpp
index 669132024af77..2c69cb0df7137 100644
--- a/clang-tools-extra/clang-tidy/misc/UnusedParametersCheck.cpp
+++ b/clang-tools-extra/clang-tidy/misc/UnusedParametersCheck.cpp
@@ -18,9 +18,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace misc {
+namespace clang::tidy::misc {
 
 namespace {
 bool isOverrideMethod(const FunctionDecl *Function) {
@@ -198,6 +196,4 @@ void UnusedParametersCheck::check(const MatchFinder::MatchResult &Result) {
   }
 }
 
-} // namespace misc
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::misc

diff  --git a/clang-tools-extra/clang-tidy/misc/UnusedUsingDeclsCheck.cpp b/clang-tools-extra/clang-tidy/misc/UnusedUsingDeclsCheck.cpp
index 6aee03083282d..3602aa4a247d6 100644
--- a/clang-tools-extra/clang-tidy/misc/UnusedUsingDeclsCheck.cpp
+++ b/clang-tools-extra/clang-tidy/misc/UnusedUsingDeclsCheck.cpp
@@ -13,9 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace misc {
+namespace clang::tidy::misc {
 
 namespace {
 
@@ -201,6 +199,4 @@ void UnusedUsingDeclsCheck::onEndOfTranslationUnit() {
   Contexts.clear();
 }
 
-} // namespace misc
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::misc

diff  --git a/clang-tools-extra/clang-tidy/misc/UseAnonymousNamespaceCheck.cpp b/clang-tools-extra/clang-tidy/misc/UseAnonymousNamespaceCheck.cpp
index 909bf793a9197..7e4bba216f0ce 100644
--- a/clang-tools-extra/clang-tidy/misc/UseAnonymousNamespaceCheck.cpp
+++ b/clang-tools-extra/clang-tidy/misc/UseAnonymousNamespaceCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace misc {
+namespace clang::tidy::misc {
 namespace {
 AST_POLYMORPHIC_MATCHER_P(isInHeaderFile,
                           AST_POLYMORPHIC_SUPPORTED_TYPES(FunctionDecl,
@@ -74,6 +72,4 @@ void UseAnonymousNamespaceCheck::check(const MatchFinder::MatchResult &Result) {
   }
 }
 
-} // namespace misc
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::misc

diff  --git a/clang-tools-extra/clang-tidy/modernize/AvoidBindCheck.cpp b/clang-tools-extra/clang-tidy/modernize/AvoidBindCheck.cpp
index 8783a547ad2b3..598a9ae4433ce 100644
--- a/clang-tools-extra/clang-tidy/modernize/AvoidBindCheck.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/AvoidBindCheck.cpp
@@ -29,9 +29,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace modernize {
+namespace clang::tidy::modernize {
 
 namespace {
 
@@ -717,6 +715,4 @@ void AvoidBindCheck::check(const MatchFinder::MatchResult &Result) {
                                        Stream.str());
 }
 
-} // namespace modernize
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::modernize

diff  --git a/clang-tools-extra/clang-tidy/modernize/AvoidCArraysCheck.cpp b/clang-tools-extra/clang-tidy/modernize/AvoidCArraysCheck.cpp
index 872dd18675940..d1b15479ffe7a 100644
--- a/clang-tools-extra/clang-tidy/modernize/AvoidCArraysCheck.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/AvoidCArraysCheck.cpp
@@ -38,9 +38,7 @@ AST_MATCHER(clang::ParmVarDecl, isArgvOfMain) {
 
 } // namespace
 
-namespace clang {
-namespace tidy {
-namespace modernize {
+namespace clang::tidy::modernize {
 
 void AvoidCArraysCheck::registerMatchers(MatchFinder *Finder) {
   Finder->addMatcher(
@@ -63,6 +61,4 @@ void AvoidCArraysCheck::check(const MatchFinder::MatchResult &Result) {
       << ArrayType->getTypePtr()->isVariableArrayType();
 }
 
-} // namespace modernize
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::modernize

diff  --git a/clang-tools-extra/clang-tidy/modernize/ConcatNestedNamespacesCheck.cpp b/clang-tools-extra/clang-tidy/modernize/ConcatNestedNamespacesCheck.cpp
index e55b260060ce0..0d815dabb6b3c 100644
--- a/clang-tools-extra/clang-tidy/modernize/ConcatNestedNamespacesCheck.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/ConcatNestedNamespacesCheck.cpp
@@ -12,9 +12,7 @@
 #include "clang/Lex/Lexer.h"
 #include <algorithm>
 
-namespace clang {
-namespace tidy {
-namespace modernize {
+namespace clang::tidy::modernize {
 
 static bool locationsInSameFile(const SourceManager &Sources,
                                 SourceLocation Loc1, SourceLocation Loc2) {
@@ -102,6 +100,4 @@ void ConcatNestedNamespacesCheck::check(
   Namespaces.clear();
 }
 
-} // namespace modernize
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::modernize

diff  --git a/clang-tools-extra/clang-tidy/modernize/DeprecatedHeadersCheck.cpp b/clang-tools-extra/clang-tidy/modernize/DeprecatedHeadersCheck.cpp
index 2498ec94a8437..7d4659c1eaac4 100644
--- a/clang-tools-extra/clang-tidy/modernize/DeprecatedHeadersCheck.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/DeprecatedHeadersCheck.cpp
@@ -19,9 +19,7 @@
 
 using IncludeMarker =
     clang::tidy::modernize::DeprecatedHeadersCheck::IncludeMarker;
-namespace clang {
-namespace tidy {
-namespace modernize {
+namespace clang::tidy::modernize {
 namespace {
 
 class IncludeModernizePPCallbacks : public PPCallbacks {
@@ -211,6 +209,4 @@ void IncludeModernizePPCallbacks::InclusionDirective(
   }
 }
 
-} // namespace modernize
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::modernize

diff  --git a/clang-tools-extra/clang-tidy/modernize/DeprecatedIosBaseAliasesCheck.cpp b/clang-tools-extra/clang-tidy/modernize/DeprecatedIosBaseAliasesCheck.cpp
index 1d818c576dc2f..a1607c83ce522 100644
--- a/clang-tools-extra/clang-tidy/modernize/DeprecatedIosBaseAliasesCheck.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/DeprecatedIosBaseAliasesCheck.cpp
@@ -13,9 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace modernize {
+namespace clang::tidy::modernize {
 
 static constexpr std::array<StringRef, 5> DeprecatedTypes = {
     "::std::ios_base::io_state", "::std::ios_base::open_mode",
@@ -72,6 +70,4 @@ void DeprecatedIosBaseAliasesCheck::check(
     diag(IoStateLoc, "'std::ios_base::%0' is deprecated") << TypeName;
 }
 
-} // namespace modernize
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::modernize

diff  --git a/clang-tools-extra/clang-tidy/modernize/IntegralLiteralExpressionMatcher.cpp b/clang-tools-extra/clang-tidy/modernize/IntegralLiteralExpressionMatcher.cpp
index ca0e99fc787a1..9b97b46d580ee 100644
--- a/clang-tools-extra/clang-tidy/modernize/IntegralLiteralExpressionMatcher.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/IntegralLiteralExpressionMatcher.cpp
@@ -12,9 +12,7 @@
 #include <cctype>
 #include <stdexcept>
 
-namespace clang {
-namespace tidy {
-namespace modernize {
+namespace clang::tidy::modernize {
 
 // Validate that this literal token is a valid integer literal.  A literal token
 // could be a floating-point token, which isn't acceptable as a value for an
@@ -285,6 +283,4 @@ LiteralSize IntegralLiteralExpressionMatcher::largestLiteralSize() const {
   return LargestSize;
 }
 
-} // namespace modernize
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::modernize

diff  --git a/clang-tools-extra/clang-tidy/modernize/LoopConvertCheck.cpp b/clang-tools-extra/clang-tidy/modernize/LoopConvertCheck.cpp
index 0056acbe5fc8a..fe9412f8d068c 100644
--- a/clang-tools-extra/clang-tidy/modernize/LoopConvertCheck.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/LoopConvertCheck.cpp
@@ -27,8 +27,7 @@
 using namespace clang::ast_matchers;
 using namespace llvm;
 
-namespace clang {
-namespace tidy {
+namespace clang::tidy {
 
 template <> struct OptionEnumMapping<modernize::Confidence::Level> {
   static llvm::ArrayRef<std::pair<modernize::Confidence::Level, StringRef>>
@@ -970,5 +969,4 @@ llvm::StringRef LoopConvertCheck::getReverseHeader() const {
 }
 
 } // namespace modernize
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy

diff  --git a/clang-tools-extra/clang-tidy/modernize/LoopConvertUtils.cpp b/clang-tools-extra/clang-tidy/modernize/LoopConvertUtils.cpp
index 0cad244bd0383..deb82b4947bbc 100644
--- a/clang-tools-extra/clang-tidy/modernize/LoopConvertUtils.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/LoopConvertUtils.cpp
@@ -27,9 +27,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace modernize {
+namespace clang::tidy::modernize {
 
 /// Tracks a stack of parent statements during traversal.
 ///
@@ -911,6 +909,4 @@ bool VariableNamer::declarationExists(StringRef Symbol) {
   return DeclFinder.findUsages(SourceStmt);
 }
 
-} // namespace modernize
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::modernize

diff  --git a/clang-tools-extra/clang-tidy/modernize/MacroToEnumCheck.cpp b/clang-tools-extra/clang-tidy/modernize/MacroToEnumCheck.cpp
index a3f5f2d3ad163..428bfb13064ee 100644
--- a/clang-tools-extra/clang-tidy/modernize/MacroToEnumCheck.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/MacroToEnumCheck.cpp
@@ -18,9 +18,7 @@
 #include <cctype>
 #include <string>
 
-namespace clang {
-namespace tidy {
-namespace modernize {
+namespace clang::tidy::modernize {
 
 static bool hasOnlyComments(SourceLocation Loc, const LangOptions &Options,
                             StringRef Text) {
@@ -556,6 +554,4 @@ void MacroToEnumCheck::check(
     PPCallback->invalidateRange(Range);
 }
 
-} // namespace modernize
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::modernize

diff  --git a/clang-tools-extra/clang-tidy/modernize/MakeSharedCheck.cpp b/clang-tools-extra/clang-tidy/modernize/MakeSharedCheck.cpp
index 5ab3f3e26be2c..69f7d9f69eeed 100644
--- a/clang-tools-extra/clang-tidy/modernize/MakeSharedCheck.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/MakeSharedCheck.cpp
@@ -13,9 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace modernize {
+namespace clang::tidy::modernize {
 
 MakeSharedCheck::MakeSharedCheck(StringRef Name, ClangTidyContext *Context)
     : MakeSmartPtrCheck(Name, Context, "std::make_shared") {}
@@ -29,6 +27,4 @@ MakeSharedCheck::getSmartPointerTypeMatcher() const {
                                      qualType().bind(PointerType)))))))));
 }
 
-} // namespace modernize
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::modernize

diff  --git a/clang-tools-extra/clang-tidy/modernize/MakeSmartPtrCheck.cpp b/clang-tools-extra/clang-tidy/modernize/MakeSmartPtrCheck.cpp
index 6d5f94de55dab..2f9f47d3f6c3e 100644
--- a/clang-tools-extra/clang-tidy/modernize/MakeSmartPtrCheck.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/MakeSmartPtrCheck.cpp
@@ -14,9 +14,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace modernize {
+namespace clang::tidy::modernize {
 
 namespace {
 
@@ -439,6 +437,4 @@ void MakeSmartPtrCheck::insertHeader(DiagnosticBuilder &Diag, FileID FD) {
   Diag << Inserter.createIncludeInsertion(FD, MakeSmartPtrFunctionHeader);
 }
 
-} // namespace modernize
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::modernize

diff  --git a/clang-tools-extra/clang-tidy/modernize/MakeUniqueCheck.cpp b/clang-tools-extra/clang-tidy/modernize/MakeUniqueCheck.cpp
index e2f812b35aea0..d4d9f700f12c9 100644
--- a/clang-tools-extra/clang-tidy/modernize/MakeUniqueCheck.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/MakeUniqueCheck.cpp
@@ -10,9 +10,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace modernize {
+namespace clang::tidy::modernize {
 
 MakeUniqueCheck::MakeUniqueCheck(StringRef Name,
                                  clang::tidy::ClangTidyContext *Context)
@@ -43,6 +41,4 @@ bool MakeUniqueCheck::isLanguageVersionSupported(
 
 // FixItHint is done by MakeSmartPtrCheck
 
-} // namespace modernize
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::modernize

diff  --git a/clang-tools-extra/clang-tidy/modernize/ModernizeTidyModule.cpp b/clang-tools-extra/clang-tidy/modernize/ModernizeTidyModule.cpp
index 08076354dbe4b..97d24e52e57f6 100644
--- a/clang-tools-extra/clang-tidy/modernize/ModernizeTidyModule.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/ModernizeTidyModule.cpp
@@ -44,8 +44,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
+namespace clang::tidy {
 namespace modernize {
 
 class ModernizeModule : public ClangTidyModule {
@@ -130,5 +129,4 @@ static ClangTidyModuleRegistry::Add<ModernizeModule> X("modernize-module",
 // and thus register the ModernizeModule.
 volatile int ModernizeModuleAnchorSource = 0;
 
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy

diff  --git a/clang-tools-extra/clang-tidy/modernize/PassByValueCheck.cpp b/clang-tools-extra/clang-tidy/modernize/PassByValueCheck.cpp
index f9dd542b5c996..ff3b3a7ce5c39 100644
--- a/clang-tools-extra/clang-tidy/modernize/PassByValueCheck.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/PassByValueCheck.cpp
@@ -18,9 +18,7 @@
 using namespace clang::ast_matchers;
 using namespace llvm;
 
-namespace clang {
-namespace tidy {
-namespace modernize {
+namespace clang::tidy::modernize {
 
 namespace {
 /// Matches move-constructible classes.
@@ -305,6 +303,4 @@ void PassByValueCheck::check(const MatchFinder::MatchResult &Result) {
               "<utility>");
 }
 
-} // namespace modernize
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::modernize

diff  --git a/clang-tools-extra/clang-tidy/modernize/RawStringLiteralCheck.cpp b/clang-tools-extra/clang-tidy/modernize/RawStringLiteralCheck.cpp
index d4b8fc8407153..57e4c4863d3b7 100644
--- a/clang-tools-extra/clang-tidy/modernize/RawStringLiteralCheck.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/RawStringLiteralCheck.cpp
@@ -13,9 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace modernize {
+namespace clang::tidy::modernize {
 
 namespace {
 
@@ -147,6 +145,4 @@ void RawStringLiteralCheck::replaceWithRawStringLiteral(
       << FixItHint::CreateReplacement(CharRange, Replacement);
 }
 
-} // namespace modernize
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::modernize

diff  --git a/clang-tools-extra/clang-tidy/modernize/RedundantVoidArgCheck.cpp b/clang-tools-extra/clang-tidy/modernize/RedundantVoidArgCheck.cpp
index 4f791d404d9da..53447c2b960f9 100644
--- a/clang-tools-extra/clang-tidy/modernize/RedundantVoidArgCheck.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/RedundantVoidArgCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace modernize {
+namespace clang::tidy::modernize {
 
 namespace {
 
@@ -287,6 +285,4 @@ void RedundantVoidArgCheck::processLambdaExpr(
   }
 }
 
-} // namespace modernize
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::modernize

diff  --git a/clang-tools-extra/clang-tidy/modernize/ReplaceAutoPtrCheck.cpp b/clang-tools-extra/clang-tidy/modernize/ReplaceAutoPtrCheck.cpp
index 84c17effb9bc4..4587b08670789 100644
--- a/clang-tools-extra/clang-tidy/modernize/ReplaceAutoPtrCheck.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/ReplaceAutoPtrCheck.cpp
@@ -16,9 +16,7 @@
 using namespace clang;
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace modernize {
+namespace clang::tidy::modernize {
 
 namespace {
 static const char AutoPtrTokenId[] = "AutoPrTokenId";
@@ -150,6 +148,4 @@ void ReplaceAutoPtrCheck::check(const MatchFinder::MatchResult &Result) {
                                       "unique_ptr");
 }
 
-} // namespace modernize
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::modernize

diff  --git a/clang-tools-extra/clang-tidy/modernize/ReplaceDisallowCopyAndAssignMacroCheck.cpp b/clang-tools-extra/clang-tidy/modernize/ReplaceDisallowCopyAndAssignMacroCheck.cpp
index 6c35e24177a3c..42be7d7a7b78c 100644
--- a/clang-tools-extra/clang-tidy/modernize/ReplaceDisallowCopyAndAssignMacroCheck.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/ReplaceDisallowCopyAndAssignMacroCheck.cpp
@@ -14,9 +14,7 @@
 #include "llvm/Support/FormatVariadic.h"
 #include <optional>
 
-namespace clang {
-namespace tidy {
-namespace modernize {
+namespace clang::tidy::modernize {
 
 namespace {
 
@@ -88,6 +86,4 @@ void ReplaceDisallowCopyAndAssignMacroCheck::storeOptions(
   Options.store(Opts, "MacroName", MacroName);
 }
 
-} // namespace modernize
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::modernize

diff  --git a/clang-tools-extra/clang-tidy/modernize/ReplaceRandomShuffleCheck.cpp b/clang-tools-extra/clang-tidy/modernize/ReplaceRandomShuffleCheck.cpp
index 2f17065b480dd..f5d13f31d7a64 100644
--- a/clang-tools-extra/clang-tidy/modernize/ReplaceRandomShuffleCheck.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/ReplaceRandomShuffleCheck.cpp
@@ -16,9 +16,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace modernize {
+namespace clang::tidy::modernize {
 
 ReplaceRandomShuffleCheck::ReplaceRandomShuffleCheck(StringRef Name,
                                                      ClangTidyContext *Context)
@@ -96,6 +94,4 @@ void ReplaceRandomShuffleCheck::check(const MatchFinder::MatchResult &Result) {
       "<random>");
 }
 
-} // namespace modernize
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::modernize

diff  --git a/clang-tools-extra/clang-tidy/modernize/ReturnBracedInitListCheck.cpp b/clang-tools-extra/clang-tidy/modernize/ReturnBracedInitListCheck.cpp
index 4c8b9571e4c7e..407de610d13a7 100644
--- a/clang-tools-extra/clang-tidy/modernize/ReturnBracedInitListCheck.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/ReturnBracedInitListCheck.cpp
@@ -14,9 +14,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace modernize {
+namespace clang::tidy::modernize {
 
 void ReturnBracedInitListCheck::registerMatchers(MatchFinder *Finder) {
   // Skip list initialization and constructors with an initializer list.
@@ -82,6 +80,4 @@ void ReturnBracedInitListCheck::check(const MatchFinder::MatchResult &Result) {
        << FixItHint::CreateReplacement(CallParensRange.getEnd(), "}");
 }
 
-} // namespace modernize
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::modernize

diff  --git a/clang-tools-extra/clang-tidy/modernize/ShrinkToFitCheck.cpp b/clang-tools-extra/clang-tidy/modernize/ShrinkToFitCheck.cpp
index 411f04eb5ee9a..b971b82507644 100644
--- a/clang-tools-extra/clang-tidy/modernize/ShrinkToFitCheck.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/ShrinkToFitCheck.cpp
@@ -14,9 +14,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace modernize {
+namespace clang::tidy::modernize {
 
 void ShrinkToFitCheck::registerMatchers(MatchFinder *Finder) {
   // Swap as a function need not to be considered, because rvalue can not
@@ -75,6 +73,4 @@ void ShrinkToFitCheck::check(const MatchFinder::MatchResult &Result) {
       << Hint;
 }
 
-} // namespace modernize
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::modernize

diff  --git a/clang-tools-extra/clang-tidy/modernize/UnaryStaticAssertCheck.cpp b/clang-tools-extra/clang-tidy/modernize/UnaryStaticAssertCheck.cpp
index c074b931e845d..81b21565667e8 100644
--- a/clang-tools-extra/clang-tidy/modernize/UnaryStaticAssertCheck.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/UnaryStaticAssertCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace modernize {
+namespace clang::tidy::modernize {
 
 void UnaryStaticAssertCheck::registerMatchers(MatchFinder *Finder) {
   Finder->addMatcher(staticAssertDecl().bind("static_assert"), this);
@@ -36,6 +34,4 @@ void UnaryStaticAssertCheck::check(const MatchFinder::MatchResult &Result) {
       << FixItHint::CreateRemoval(AssertMessage->getSourceRange());
 }
 
-} // namespace modernize
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::modernize

diff  --git a/clang-tools-extra/clang-tidy/modernize/UseAutoCheck.cpp b/clang-tools-extra/clang-tidy/modernize/UseAutoCheck.cpp
index a4a81ce6cd77f..7af30e688b6a7 100644
--- a/clang-tools-extra/clang-tidy/modernize/UseAutoCheck.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/UseAutoCheck.cpp
@@ -17,9 +17,7 @@ using namespace clang;
 using namespace clang::ast_matchers;
 using namespace clang::ast_matchers::internal;
 
-namespace clang {
-namespace tidy {
-namespace modernize {
+namespace clang::tidy::modernize {
 namespace {
 
 const char IteratorDeclStmtId[] = "iterator_decl";
@@ -449,6 +447,4 @@ void UseAutoCheck::check(const MatchFinder::MatchResult &Result) {
   }
 }
 
-} // namespace modernize
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::modernize

diff  --git a/clang-tools-extra/clang-tidy/modernize/UseBoolLiteralsCheck.cpp b/clang-tools-extra/clang-tidy/modernize/UseBoolLiteralsCheck.cpp
index ad11e39f1f1bb..c8e6bf47bb82f 100644
--- a/clang-tools-extra/clang-tidy/modernize/UseBoolLiteralsCheck.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/UseBoolLiteralsCheck.cpp
@@ -13,9 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace modernize {
+namespace clang::tidy::modernize {
 
 UseBoolLiteralsCheck::UseBoolLiteralsCheck(StringRef Name,
                                            ClangTidyContext *Context)
@@ -74,6 +72,4 @@ void UseBoolLiteralsCheck::check(const MatchFinder::MatchResult &Result) {
         Expression->getSourceRange(), LiteralBooleanValue ? "true" : "false");
 }
 
-} // namespace modernize
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::modernize

diff  --git a/clang-tools-extra/clang-tidy/modernize/UseDefaultMemberInitCheck.cpp b/clang-tools-extra/clang-tidy/modernize/UseDefaultMemberInitCheck.cpp
index 6f8c984da2a8f..d3e7bd4b8032c 100644
--- a/clang-tools-extra/clang-tidy/modernize/UseDefaultMemberInitCheck.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/UseDefaultMemberInitCheck.cpp
@@ -13,9 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace modernize {
+namespace clang::tidy::modernize {
 
 namespace {
 AST_MATCHER_P(InitListExpr, initCountIs, unsigned, N) {
@@ -296,6 +294,4 @@ void UseDefaultMemberInitCheck::checkExistingInit(
       << FixItHint::CreateRemoval(Init->getSourceRange());
 }
 
-} // namespace modernize
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::modernize

diff  --git a/clang-tools-extra/clang-tidy/modernize/UseEmplaceCheck.cpp b/clang-tools-extra/clang-tidy/modernize/UseEmplaceCheck.cpp
index 1b7853d781ce9..045d7fb852230 100644
--- a/clang-tools-extra/clang-tidy/modernize/UseEmplaceCheck.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/UseEmplaceCheck.cpp
@@ -10,9 +10,7 @@
 #include "../utils/OptionsUtils.h"
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace modernize {
+namespace clang::tidy::modernize {
 
 namespace {
 // Identical to hasAnyName, except it does not take template specifiers into
@@ -374,6 +372,4 @@ void UseEmplaceCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
                 utils::options::serializeStringList(EmplacyFunctions));
 }
 
-} // namespace modernize
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::modernize

diff  --git a/clang-tools-extra/clang-tidy/modernize/UseEqualsDefaultCheck.cpp b/clang-tools-extra/clang-tidy/modernize/UseEqualsDefaultCheck.cpp
index aac7c8866e1eb..d48d43f2677f0 100644
--- a/clang-tools-extra/clang-tidy/modernize/UseEqualsDefaultCheck.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/UseEqualsDefaultCheck.cpp
@@ -16,9 +16,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace modernize {
+namespace clang::tidy::modernize {
 
 static const char SpecialFunction[] = "SpecialFunction";
 
@@ -355,6 +353,4 @@ void UseEqualsDefaultCheck::check(const MatchFinder::MatchResult &Result) {
   }
 }
 
-} // namespace modernize
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::modernize

diff  --git a/clang-tools-extra/clang-tidy/modernize/UseEqualsDeleteCheck.cpp b/clang-tools-extra/clang-tidy/modernize/UseEqualsDeleteCheck.cpp
index 7d5ae89551731..b82c01ee7708c 100644
--- a/clang-tools-extra/clang-tidy/modernize/UseEqualsDeleteCheck.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/UseEqualsDeleteCheck.cpp
@@ -13,9 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace modernize {
+namespace clang::tidy::modernize {
 
 static const char SpecialFunction[] = "SpecialFunction";
 static const char DeletedNotPublic[] = "DeletedNotPublic";
@@ -75,6 +73,4 @@ void UseEqualsDeleteCheck::check(const MatchFinder::MatchResult &Result) {
   }
 }
 
-} // namespace modernize
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::modernize

diff  --git a/clang-tools-extra/clang-tidy/modernize/UseNodiscardCheck.cpp b/clang-tools-extra/clang-tidy/modernize/UseNodiscardCheck.cpp
index 1b2a80d11d9ca..16ea46e71578c 100644
--- a/clang-tools-extra/clang-tidy/modernize/UseNodiscardCheck.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/UseNodiscardCheck.cpp
@@ -14,9 +14,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace modernize {
+namespace clang::tidy::modernize {
 
 static bool doesNoDiscardMacroExist(ASTContext &Context,
                                     const llvm::StringRef &MacroId) {
@@ -146,6 +144,4 @@ bool UseNodiscardCheck::isLanguageVersionSupported(
   return LangOpts.CPlusPlus;
 }
 
-} // namespace modernize
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::modernize

diff  --git a/clang-tools-extra/clang-tidy/modernize/UseNoexceptCheck.cpp b/clang-tools-extra/clang-tidy/modernize/UseNoexceptCheck.cpp
index 6cc6b0ff6aa47..9ba9e6dd8d2c2 100644
--- a/clang-tools-extra/clang-tidy/modernize/UseNoexceptCheck.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/UseNoexceptCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace modernize {
+namespace clang::tidy::modernize {
 
 namespace {
 AST_MATCHER(NamedDecl, isValid) { return !Node.isInvalidDecl(); }
@@ -105,6 +103,4 @@ void UseNoexceptCheck::check(const MatchFinder::MatchResult &Result) {
       << ReplacementStr.empty() << ReplacementStr << FixIt;
 }
 
-} // namespace modernize
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::modernize

diff  --git a/clang-tools-extra/clang-tidy/modernize/UseNullptrCheck.cpp b/clang-tools-extra/clang-tidy/modernize/UseNullptrCheck.cpp
index 220a310a0d4e4..927033449b331 100644
--- a/clang-tools-extra/clang-tidy/modernize/UseNullptrCheck.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/UseNullptrCheck.cpp
@@ -16,9 +16,7 @@ using namespace clang;
 using namespace clang::ast_matchers;
 using namespace llvm;
 
-namespace clang {
-namespace tidy {
-namespace modernize {
+namespace clang::tidy::modernize {
 namespace {
 
 const char CastSequence[] = "sequence";
@@ -510,6 +508,4 @@ void UseNullptrCheck::check(const MatchFinder::MatchResult &Result) {
       .TraverseStmt(const_cast<CastExpr *>(NullCast));
 }
 
-} // namespace modernize
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::modernize

diff  --git a/clang-tools-extra/clang-tidy/modernize/UseOverrideCheck.cpp b/clang-tools-extra/clang-tidy/modernize/UseOverrideCheck.cpp
index c78fd7f14a404..a3201c825d387 100644
--- a/clang-tools-extra/clang-tidy/modernize/UseOverrideCheck.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/UseOverrideCheck.cpp
@@ -13,9 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace modernize {
+namespace clang::tidy::modernize {
 
 UseOverrideCheck::UseOverrideCheck(StringRef Name, ClangTidyContext *Context)
     : ClangTidyCheck(Name, Context),
@@ -228,6 +226,4 @@ void UseOverrideCheck::check(const MatchFinder::MatchResult &Result) {
   }
 }
 
-} // namespace modernize
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::modernize

diff  --git a/clang-tools-extra/clang-tidy/modernize/UseTrailingReturnTypeCheck.cpp b/clang-tools-extra/clang-tidy/modernize/UseTrailingReturnTypeCheck.cpp
index 070ba9a5451c4..00c7d419037fe 100644
--- a/clang-tools-extra/clang-tidy/modernize/UseTrailingReturnTypeCheck.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/UseTrailingReturnTypeCheck.cpp
@@ -19,9 +19,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace modernize {
+namespace clang::tidy::modernize {
 namespace {
 struct UnqualNameVisitor : public RecursiveASTVisitor<UnqualNameVisitor> {
 public:
@@ -496,6 +494,4 @@ void UseTrailingReturnTypeCheck::check(const MatchFinder::MatchResult &Result) {
       << FixItHint::CreateInsertion(InsertionLoc, " -> " + ReturnType);
 }
 
-} // namespace modernize
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::modernize

diff  --git a/clang-tools-extra/clang-tidy/modernize/UseTransparentFunctorsCheck.cpp b/clang-tools-extra/clang-tidy/modernize/UseTransparentFunctorsCheck.cpp
index 58bd9e76eaf76..2223a1999f736 100644
--- a/clang-tools-extra/clang-tidy/modernize/UseTransparentFunctorsCheck.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/UseTransparentFunctorsCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace modernize {
+namespace clang::tidy::modernize {
 
 UseTransparentFunctorsCheck::UseTransparentFunctorsCheck(
     StringRef Name, ClangTidyContext *Context)
@@ -124,6 +122,4 @@ void UseTransparentFunctorsCheck::check(
                                   FunctorTypeLoc.getArgLoc(0).getSourceRange());
 }
 
-} // namespace modernize
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::modernize

diff  --git a/clang-tools-extra/clang-tidy/modernize/UseUncaughtExceptionsCheck.cpp b/clang-tools-extra/clang-tidy/modernize/UseUncaughtExceptionsCheck.cpp
index b9d68cea8ced0..06a2778b46dd7 100644
--- a/clang-tools-extra/clang-tidy/modernize/UseUncaughtExceptionsCheck.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/UseUncaughtExceptionsCheck.cpp
@@ -13,9 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace modernize {
+namespace clang::tidy::modernize {
 
 void UseUncaughtExceptionsCheck::registerMatchers(MatchFinder *Finder) {
   std::string MatchText = "::std::uncaught_exception";
@@ -97,6 +95,4 @@ void UseUncaughtExceptionsCheck::check(const MatchFinder::MatchResult &Result) {
   }
 }
 
-} // namespace modernize
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::modernize

diff  --git a/clang-tools-extra/clang-tidy/modernize/UseUsingCheck.cpp b/clang-tools-extra/clang-tidy/modernize/UseUsingCheck.cpp
index fa3cfa5e9cfca..c1af8b5bfa11c 100644
--- a/clang-tools-extra/clang-tidy/modernize/UseUsingCheck.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/UseUsingCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace modernize {
+namespace clang::tidy::modernize {
 
 static constexpr llvm::StringLiteral ParentDeclName = "parent-decl";
 static constexpr llvm::StringLiteral TagDeclName = "tag-decl";
@@ -142,6 +140,4 @@ void UseUsingCheck::check(const MatchFinder::MatchResult &Result) {
   std::string Replacement = Using + Name + " = " + Type;
   Diag << FixItHint::CreateReplacement(ReplaceRange, Replacement);
 }
-} // namespace modernize
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::modernize

diff  --git a/clang-tools-extra/clang-tidy/mpi/BufferDerefCheck.cpp b/clang-tools-extra/clang-tidy/mpi/BufferDerefCheck.cpp
index ebe9658d8b2b1..a144296c47b8c 100644
--- a/clang-tools-extra/clang-tidy/mpi/BufferDerefCheck.cpp
+++ b/clang-tools-extra/clang-tidy/mpi/BufferDerefCheck.cpp
@@ -13,9 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace mpi {
+namespace clang::tidy::mpi {
 
 void BufferDerefCheck::registerMatchers(MatchFinder *Finder) {
   Finder->addMatcher(callExpr().bind("CE"), this);
@@ -128,6 +126,4 @@ void BufferDerefCheck::checkBuffers(ArrayRef<const Type *> BufferTypes,
 }
 
 void BufferDerefCheck::onEndOfTranslationUnit() { FuncClassifier.reset(); }
-} // namespace mpi
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::mpi

diff  --git a/clang-tools-extra/clang-tidy/mpi/MPITidyModule.cpp b/clang-tools-extra/clang-tidy/mpi/MPITidyModule.cpp
index b295d5ff3b9f4..166d71e130db5 100644
--- a/clang-tools-extra/clang-tidy/mpi/MPITidyModule.cpp
+++ b/clang-tools-extra/clang-tidy/mpi/MPITidyModule.cpp
@@ -12,8 +12,7 @@
 #include "BufferDerefCheck.h"
 #include "TypeMismatchCheck.h"
 
-namespace clang {
-namespace tidy {
+namespace clang::tidy {
 namespace mpi {
 
 class MPIModule : public ClangTidyModule {
@@ -34,5 +33,4 @@ static ClangTidyModuleRegistry::Add<mpi::MPIModule>
 // and thus register the MPIModule.
 volatile int MPIModuleAnchorSource = 0;
 
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy

diff  --git a/clang-tools-extra/clang-tidy/mpi/TypeMismatchCheck.cpp b/clang-tools-extra/clang-tidy/mpi/TypeMismatchCheck.cpp
index 6f7bfe69c54eb..903fd42d12ab1 100644
--- a/clang-tools-extra/clang-tidy/mpi/TypeMismatchCheck.cpp
+++ b/clang-tools-extra/clang-tidy/mpi/TypeMismatchCheck.cpp
@@ -14,9 +14,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace mpi {
+namespace clang::tidy::mpi {
 
 /// Check if a BuiltinType::Kind matches the MPI datatype.
 ///
@@ -330,6 +328,4 @@ void TypeMismatchCheck::checkArguments(ArrayRef<const Type *> BufferTypes,
 }
 
 void TypeMismatchCheck::onEndOfTranslationUnit() { FuncClassifier.reset(); }
-} // namespace mpi
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::mpi

diff  --git a/clang-tools-extra/clang-tidy/objc/AssertEquals.cpp b/clang-tools-extra/clang-tidy/objc/AssertEquals.cpp
index 198e7f0226d14..da98e19c67412 100644
--- a/clang-tools-extra/clang-tidy/objc/AssertEquals.cpp
+++ b/clang-tools-extra/clang-tidy/objc/AssertEquals.cpp
@@ -13,9 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace objc {
+namespace clang::tidy::objc {
 
 // Mapping from `XCTAssert*Equal` to `XCTAssert*EqualObjects` name.
 static const std::map<std::string, std::string> &NameMap() {
@@ -60,6 +58,4 @@ void AssertEquals::check(const ast_matchers::MatchFinder::MatchResult &result) {
   }
 }
 
-} // namespace objc
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::objc

diff  --git a/clang-tools-extra/clang-tidy/objc/AvoidNSErrorInitCheck.cpp b/clang-tools-extra/clang-tidy/objc/AvoidNSErrorInitCheck.cpp
index de3fdd6460138..3624cab10a509 100644
--- a/clang-tools-extra/clang-tidy/objc/AvoidNSErrorInitCheck.cpp
+++ b/clang-tools-extra/clang-tidy/objc/AvoidNSErrorInitCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace objc {
+namespace clang::tidy::objc {
 
 void AvoidNSErrorInitCheck::registerMatchers(MatchFinder *Finder) {
   Finder->addMatcher(objcMessageExpr(hasSelector("init"),
@@ -31,6 +29,4 @@ void AvoidNSErrorInitCheck::check(const MatchFinder::MatchResult &Result) {
        "create a new NSError");
 }
 
-}  // namespace objc
-}  // namespace tidy
-}  // namespace clang
+} // namespace clang::tidy::objc

diff  --git a/clang-tools-extra/clang-tidy/objc/DeallocInCategoryCheck.cpp b/clang-tools-extra/clang-tidy/objc/DeallocInCategoryCheck.cpp
index 8c5ecb778397d..d18815358b837 100644
--- a/clang-tools-extra/clang-tidy/objc/DeallocInCategoryCheck.cpp
+++ b/clang-tools-extra/clang-tidy/objc/DeallocInCategoryCheck.cpp
@@ -13,9 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace objc {
+namespace clang::tidy::objc {
 
 void DeallocInCategoryCheck::registerMatchers(MatchFinder *Finder) {
   // Non-NSObject/NSProxy-derived objects may not have -dealloc as a special
@@ -37,6 +35,4 @@ void DeallocInCategoryCheck::check(const MatchFinder::MatchResult &Result) {
       << CID;
 }
 
-} // namespace objc
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::objc

diff  --git a/clang-tools-extra/clang-tidy/objc/ForbiddenSubclassingCheck.cpp b/clang-tools-extra/clang-tidy/objc/ForbiddenSubclassingCheck.cpp
index 4e69ac974c7b3..21ba41d66458d 100644
--- a/clang-tools-extra/clang-tidy/objc/ForbiddenSubclassingCheck.cpp
+++ b/clang-tools-extra/clang-tidy/objc/ForbiddenSubclassingCheck.cpp
@@ -15,9 +15,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace objc {
+namespace clang::tidy::objc {
 
 namespace {
 
@@ -80,6 +78,4 @@ void ForbiddenSubclassingCheck::storeOptions(
       utils::options::serializeStringList(ForbiddenSuperClassNames));
 }
 
-} // namespace objc
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::objc

diff  --git a/clang-tools-extra/clang-tidy/objc/MissingHashCheck.cpp b/clang-tools-extra/clang-tidy/objc/MissingHashCheck.cpp
index 26104ed8f1969..42f383edc67ed 100644
--- a/clang-tools-extra/clang-tidy/objc/MissingHashCheck.cpp
+++ b/clang-tools-extra/clang-tidy/objc/MissingHashCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace objc {
+namespace clang::tidy::objc {
 
 namespace {
 
@@ -53,6 +51,4 @@ void MissingHashCheck::check(const MatchFinder::MatchResult &Result) {
       << ID;
 }
 
-} // namespace objc
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::objc

diff  --git a/clang-tools-extra/clang-tidy/objc/NSDateFormatterCheck.cpp b/clang-tools-extra/clang-tidy/objc/NSDateFormatterCheck.cpp
index f8a4d6e95df0a..fe18958ded1fd 100644
--- a/clang-tools-extra/clang-tidy/objc/NSDateFormatterCheck.cpp
+++ b/clang-tools-extra/clang-tidy/objc/NSDateFormatterCheck.cpp
@@ -13,9 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace objc {
+namespace clang::tidy::objc {
 
 void NSDateFormatterCheck::registerMatchers(MatchFinder *Finder) {
   // Adding matchers.
@@ -105,6 +103,4 @@ void NSDateFormatterCheck::check(const MatchFinder::MatchResult &Result) {
   }
 }
 
-} // namespace objc
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::objc

diff  --git a/clang-tools-extra/clang-tidy/objc/NSInvocationArgumentLifetimeCheck.cpp b/clang-tools-extra/clang-tidy/objc/NSInvocationArgumentLifetimeCheck.cpp
index c41336f1a4880..bd9bdd1701975 100644
--- a/clang-tools-extra/clang-tidy/objc/NSInvocationArgumentLifetimeCheck.cpp
+++ b/clang-tools-extra/clang-tidy/objc/NSInvocationArgumentLifetimeCheck.cpp
@@ -28,9 +28,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace objc {
+namespace clang::tidy::objc {
 namespace {
 
 static constexpr StringRef WeakText = "__weak";
@@ -142,6 +140,4 @@ void NSInvocationArgumentLifetimeCheck::check(
     Diag << *Hint;
 }
 
-} // namespace objc
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::objc

diff  --git a/clang-tools-extra/clang-tidy/objc/ObjCTidyModule.cpp b/clang-tools-extra/clang-tidy/objc/ObjCTidyModule.cpp
index 0cfab1fb79939..b6f8888ed389a 100644
--- a/clang-tools-extra/clang-tidy/objc/ObjCTidyModule.cpp
+++ b/clang-tools-extra/clang-tidy/objc/ObjCTidyModule.cpp
@@ -21,8 +21,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
+namespace clang::tidy {
 namespace objc {
 
 class ObjCModule : public ClangTidyModule {
@@ -59,5 +58,4 @@ static ClangTidyModuleRegistry::Add<ObjCModule> X(
 // and thus register the ObjCModule.
 volatile int ObjCModuleAnchorSource = 0;
 
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy

diff  --git a/clang-tools-extra/clang-tidy/objc/PropertyDeclarationCheck.cpp b/clang-tools-extra/clang-tidy/objc/PropertyDeclarationCheck.cpp
index 758d397a445e0..d72c17ac55f62 100644
--- a/clang-tools-extra/clang-tidy/objc/PropertyDeclarationCheck.cpp
+++ b/clang-tools-extra/clang-tidy/objc/PropertyDeclarationCheck.cpp
@@ -18,9 +18,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace objc {
+namespace clang::tidy::objc {
 
 namespace {
 
@@ -133,6 +131,4 @@ void PropertyDeclarationCheck::check(const MatchFinder::MatchResult &Result) {
       << generateFixItHint(MatchedDecl, StandardProperty);
 }
 
-}  // namespace objc
-}  // namespace tidy
-}  // namespace clang
+} // namespace clang::tidy::objc

diff  --git a/clang-tools-extra/clang-tidy/objc/SuperSelfCheck.cpp b/clang-tools-extra/clang-tidy/objc/SuperSelfCheck.cpp
index 75735a38036ab..951cbc52c9a99 100644
--- a/clang-tools-extra/clang-tidy/objc/SuperSelfCheck.cpp
+++ b/clang-tools-extra/clang-tidy/objc/SuperSelfCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace objc {
+namespace clang::tidy::objc {
 
 namespace {
 
@@ -104,6 +102,4 @@ void SuperSelfCheck::check(const MatchFinder::MatchResult &Result) {
                                        StringRef("[super init]"));
 }
 
-} // namespace objc
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::objc

diff  --git a/clang-tools-extra/clang-tidy/openmp/ExceptionEscapeCheck.cpp b/clang-tools-extra/clang-tidy/openmp/ExceptionEscapeCheck.cpp
index aa06941d93457..b414fd3b4d1a3 100644
--- a/clang-tools-extra/clang-tidy/openmp/ExceptionEscapeCheck.cpp
+++ b/clang-tools-extra/clang-tidy/openmp/ExceptionEscapeCheck.cpp
@@ -17,9 +17,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace openmp {
+namespace clang::tidy::openmp {
 
 ExceptionEscapeCheck::ExceptionEscapeCheck(StringRef Name,
                                            ClangTidyContext *Context)
@@ -71,6 +69,4 @@ void ExceptionEscapeCheck::check(const MatchFinder::MatchResult &Result) {
       << getOpenMPDirectiveName(Directive->getDirectiveKind());
 }
 
-} // namespace openmp
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::openmp

diff  --git a/clang-tools-extra/clang-tidy/openmp/OpenMPTidyModule.cpp b/clang-tools-extra/clang-tidy/openmp/OpenMPTidyModule.cpp
index cb0e247ee29e0..37092f49b25d6 100644
--- a/clang-tools-extra/clang-tidy/openmp/OpenMPTidyModule.cpp
+++ b/clang-tools-extra/clang-tidy/openmp/OpenMPTidyModule.cpp
@@ -12,8 +12,7 @@
 #include "ExceptionEscapeCheck.h"
 #include "UseDefaultNoneCheck.h"
 
-namespace clang {
-namespace tidy {
+namespace clang::tidy {
 namespace openmp {
 
 /// This module is for OpenMP-specific checks.
@@ -37,5 +36,4 @@ static ClangTidyModuleRegistry::Add<OpenMPModule>
 // and thus register the OpenMPModule.
 volatile int OpenMPModuleAnchorSource = 0;
 
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy

diff  --git a/clang-tools-extra/clang-tidy/openmp/UseDefaultNoneCheck.cpp b/clang-tools-extra/clang-tidy/openmp/UseDefaultNoneCheck.cpp
index 724e9b9b9cbc4..f886d43188617 100644
--- a/clang-tools-extra/clang-tidy/openmp/UseDefaultNoneCheck.cpp
+++ b/clang-tools-extra/clang-tidy/openmp/UseDefaultNoneCheck.cpp
@@ -17,9 +17,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace openmp {
+namespace clang::tidy::openmp {
 
 void UseDefaultNoneCheck::registerMatchers(MatchFinder *Finder) {
   Finder->addMatcher(
@@ -55,6 +53,4 @@ void UseDefaultNoneCheck::check(const MatchFinder::MatchResult &Result) {
       << getOpenMPDirectiveName(Directive->getDirectiveKind());
 }
 
-} // namespace openmp
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::openmp

diff  --git a/clang-tools-extra/clang-tidy/performance/FasterStringFindCheck.cpp b/clang-tools-extra/clang-tidy/performance/FasterStringFindCheck.cpp
index fba4fb9781309..d932b5fb936cb 100644
--- a/clang-tools-extra/clang-tidy/performance/FasterStringFindCheck.cpp
+++ b/clang-tools-extra/clang-tidy/performance/FasterStringFindCheck.cpp
@@ -15,9 +15,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace performance {
+namespace clang::tidy::performance {
 
 namespace {
 
@@ -95,6 +93,4 @@ void FasterStringFindCheck::check(const MatchFinder::MatchResult &Result) {
              *Replacement);
 }
 
-} // namespace performance
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::performance

diff  --git a/clang-tools-extra/clang-tidy/performance/ForRangeCopyCheck.cpp b/clang-tools-extra/clang-tidy/performance/ForRangeCopyCheck.cpp
index 8ffbd9f3fd6bf..5bfa6fb0d02d5 100644
--- a/clang-tools-extra/clang-tidy/performance/ForRangeCopyCheck.cpp
+++ b/clang-tools-extra/clang-tidy/performance/ForRangeCopyCheck.cpp
@@ -18,9 +18,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace performance {
+namespace clang::tidy::performance {
 
 ForRangeCopyCheck::ForRangeCopyCheck(StringRef Name, ClangTidyContext *Context)
     : ClangTidyCheck(Name, Context),
@@ -132,6 +130,4 @@ bool ForRangeCopyCheck::handleCopyIsOnlyConstReferenced(
   return false;
 }
 
-} // namespace performance
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::performance

diff  --git a/clang-tools-extra/clang-tidy/performance/ImplicitConversionInLoopCheck.cpp b/clang-tools-extra/clang-tidy/performance/ImplicitConversionInLoopCheck.cpp
index 61e8366b007a0..86fca0722dcd8 100644
--- a/clang-tools-extra/clang-tidy/performance/ImplicitConversionInLoopCheck.cpp
+++ b/clang-tools-extra/clang-tidy/performance/ImplicitConversionInLoopCheck.cpp
@@ -16,9 +16,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace performance {
+namespace clang::tidy::performance {
 
 // Checks if the stmt is a ImplicitCastExpr with a CastKind that is not a NoOp.
 // The subtlety is that in some cases (user defined conversions), we can
@@ -101,6 +99,4 @@ void ImplicitConversionInLoopCheck::reportAndFix(const ASTContext *Context,
   diag(VD->getBeginLoc(), Message) << VD << ConstRefType;
 }
 
-} // namespace performance
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::performance

diff  --git a/clang-tools-extra/clang-tidy/performance/InefficientAlgorithmCheck.cpp b/clang-tools-extra/clang-tidy/performance/InefficientAlgorithmCheck.cpp
index cd221f2d938b9..3c8751dbdd733 100644
--- a/clang-tools-extra/clang-tidy/performance/InefficientAlgorithmCheck.cpp
+++ b/clang-tools-extra/clang-tidy/performance/InefficientAlgorithmCheck.cpp
@@ -13,9 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace performance {
+namespace clang::tidy::performance {
 
 static bool areTypesCompatible(QualType Left, QualType Right) {
   if (const auto *LeftRefType = Left->getAs<ReferenceType>())
@@ -148,6 +146,4 @@ void InefficientAlgorithmCheck::check(const MatchFinder::MatchResult &Result) {
       << Hint;
 }
 
-} // namespace performance
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::performance

diff  --git a/clang-tools-extra/clang-tidy/performance/InefficientStringConcatenationCheck.cpp b/clang-tools-extra/clang-tidy/performance/InefficientStringConcatenationCheck.cpp
index f73643f609c5d..9e4e3f63e19cf 100644
--- a/clang-tools-extra/clang-tidy/performance/InefficientStringConcatenationCheck.cpp
+++ b/clang-tools-extra/clang-tidy/performance/InefficientStringConcatenationCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace performance {
+namespace clang::tidy::performance {
 
 void InefficientStringConcatenationCheck::storeOptions(
     ClangTidyOptions::OptionMap &Opts) {
@@ -79,6 +77,4 @@ void InefficientStringConcatenationCheck::check(
     diag(PlusOperator->getExprLoc(), DiagMsg);
 }
 
-} // namespace performance
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::performance

diff  --git a/clang-tools-extra/clang-tidy/performance/InefficientVectorOperationCheck.cpp b/clang-tools-extra/clang-tidy/performance/InefficientVectorOperationCheck.cpp
index d98df11b3f126..20aea5a79fe9a 100644
--- a/clang-tools-extra/clang-tidy/performance/InefficientVectorOperationCheck.cpp
+++ b/clang-tools-extra/clang-tidy/performance/InefficientVectorOperationCheck.cpp
@@ -15,9 +15,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace performance {
+namespace clang::tidy::performance {
 
 namespace {
 
@@ -273,6 +271,4 @@ void InefficientVectorOperationCheck::check(
   }
 }
 
-} // namespace performance
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::performance

diff  --git a/clang-tools-extra/clang-tidy/performance/MoveConstArgCheck.cpp b/clang-tools-extra/clang-tidy/performance/MoveConstArgCheck.cpp
index 9a9c915d0296f..8d4c6de8dca72 100644
--- a/clang-tools-extra/clang-tidy/performance/MoveConstArgCheck.cpp
+++ b/clang-tools-extra/clang-tidy/performance/MoveConstArgCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace performance {
+namespace clang::tidy::performance {
 
 static void replaceCallWithArg(const CallExpr *Call, DiagnosticBuilder &Diag,
                                const SourceManager &SM,
@@ -206,6 +204,4 @@ void MoveConstArgCheck::check(const MatchFinder::MatchResult &Result) {
   }
 }
 
-} // namespace performance
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::performance

diff  --git a/clang-tools-extra/clang-tidy/performance/MoveConstructorInitCheck.cpp b/clang-tools-extra/clang-tidy/performance/MoveConstructorInitCheck.cpp
index dd6e5a816ded1..0f47b40280b2b 100644
--- a/clang-tools-extra/clang-tidy/performance/MoveConstructorInitCheck.cpp
+++ b/clang-tools-extra/clang-tidy/performance/MoveConstructorInitCheck.cpp
@@ -13,9 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace performance {
+namespace clang::tidy::performance {
 
 MoveConstructorInitCheck::MoveConstructorInitCheck(StringRef Name,
                                                    ClangTidyContext *Context)
@@ -84,6 +82,4 @@ void MoveConstructorInitCheck::check(const MatchFinder::MatchResult &Result) {
   }
 }
 
-} // namespace performance
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::performance

diff  --git a/clang-tools-extra/clang-tidy/performance/NoAutomaticMoveCheck.cpp b/clang-tools-extra/clang-tidy/performance/NoAutomaticMoveCheck.cpp
index 21eba9af0997d..b9c411e266998 100644
--- a/clang-tools-extra/clang-tidy/performance/NoAutomaticMoveCheck.cpp
+++ b/clang-tools-extra/clang-tidy/performance/NoAutomaticMoveCheck.cpp
@@ -14,9 +14,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace performance {
+namespace clang::tidy::performance {
 
 NoAutomaticMoveCheck::NoAutomaticMoveCheck(StringRef Name,
                                            ClangTidyContext *Context)
@@ -67,6 +65,4 @@ void NoAutomaticMoveCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
                 utils::options::serializeStringList(AllowedTypes));
 }
 
-} // namespace performance
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::performance

diff  --git a/clang-tools-extra/clang-tidy/performance/NoIntToPtrCheck.cpp b/clang-tools-extra/clang-tidy/performance/NoIntToPtrCheck.cpp
index bc82a21bbf5a5..f7a56c7b10c8a 100644
--- a/clang-tools-extra/clang-tidy/performance/NoIntToPtrCheck.cpp
+++ b/clang-tools-extra/clang-tidy/performance/NoIntToPtrCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace performance {
+namespace clang::tidy::performance {
 
 void NoIntToPtrCheck::registerMatchers(MatchFinder *Finder) {
   Finder->addMatcher(castExpr(hasCastKind(CK_IntegralToPointer),
@@ -29,6 +27,4 @@ void NoIntToPtrCheck::check(const MatchFinder::MatchResult &Result) {
        "integer to pointer cast pessimizes optimization opportunities");
 }
 
-} // namespace performance
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::performance

diff  --git a/clang-tools-extra/clang-tidy/performance/NoexceptMoveConstructorCheck.cpp b/clang-tools-extra/clang-tidy/performance/NoexceptMoveConstructorCheck.cpp
index 782498bd69e9a..3e651391e143b 100644
--- a/clang-tools-extra/clang-tidy/performance/NoexceptMoveConstructorCheck.cpp
+++ b/clang-tools-extra/clang-tidy/performance/NoexceptMoveConstructorCheck.cpp
@@ -14,9 +14,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace performance {
+namespace clang::tidy::performance {
 
 void NoexceptMoveConstructorCheck::registerMatchers(MatchFinder *Finder) {
   Finder->addMatcher(
@@ -77,6 +75,4 @@ void NoexceptMoveConstructorCheck::check(
   }
 }
 
-} // namespace performance
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::performance

diff  --git a/clang-tools-extra/clang-tidy/performance/PerformanceTidyModule.cpp b/clang-tools-extra/clang-tidy/performance/PerformanceTidyModule.cpp
index ba9d7eed55e23..30a195f76b4ec 100644
--- a/clang-tools-extra/clang-tidy/performance/PerformanceTidyModule.cpp
+++ b/clang-tools-extra/clang-tidy/performance/PerformanceTidyModule.cpp
@@ -25,8 +25,7 @@
 #include "UnnecessaryCopyInitialization.h"
 #include "UnnecessaryValueParamCheck.h"
 
-namespace clang {
-namespace tidy {
+namespace clang::tidy {
 namespace performance {
 
 class PerformanceModule : public ClangTidyModule {
@@ -74,5 +73,4 @@ static ClangTidyModuleRegistry::Add<PerformanceModule>
 // and thus register the PerformanceModule.
 volatile int PerformanceModuleAnchorSource = 0;
 
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy

diff  --git a/clang-tools-extra/clang-tidy/performance/TriviallyDestructibleCheck.cpp b/clang-tools-extra/clang-tidy/performance/TriviallyDestructibleCheck.cpp
index 1c20e58131038..adfedb4e84c47 100644
--- a/clang-tools-extra/clang-tidy/performance/TriviallyDestructibleCheck.cpp
+++ b/clang-tools-extra/clang-tidy/performance/TriviallyDestructibleCheck.cpp
@@ -16,9 +16,7 @@ using namespace clang::ast_matchers;
 using namespace clang::ast_matchers::internal;
 using namespace clang::tidy::matchers;
 
-namespace clang {
-namespace tidy {
-namespace performance {
+namespace clang::tidy::performance {
 
 namespace {
 
@@ -74,6 +72,4 @@ void TriviallyDestructibleCheck::check(const MatchFinder::MatchResult &Result) {
        DiagnosticIDs::Note);
 }
 
-} // namespace performance
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::performance

diff  --git a/clang-tools-extra/clang-tidy/performance/TypePromotionInMathFnCheck.cpp b/clang-tools-extra/clang-tidy/performance/TypePromotionInMathFnCheck.cpp
index 4f7e6fe6f2981..869830aaf9d66 100644
--- a/clang-tools-extra/clang-tidy/performance/TypePromotionInMathFnCheck.cpp
+++ b/clang-tools-extra/clang-tidy/performance/TypePromotionInMathFnCheck.cpp
@@ -15,9 +15,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace performance {
+namespace clang::tidy::performance {
 
 namespace {
 AST_MATCHER_P(Type, isBuiltinType, BuiltinType::Kind, Kind) {
@@ -195,6 +193,4 @@ void TypePromotionInMathFnCheck::check(const MatchFinder::MatchResult &Result) {
         "<cmath>");
 }
 
-} // namespace performance
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::performance

diff  --git a/clang-tools-extra/clang-tidy/performance/UnnecessaryCopyInitialization.cpp b/clang-tools-extra/clang-tidy/performance/UnnecessaryCopyInitialization.cpp
index 7cdd4d3fb0014..d4e216239ea94 100644
--- a/clang-tools-extra/clang-tidy/performance/UnnecessaryCopyInitialization.cpp
+++ b/clang-tools-extra/clang-tidy/performance/UnnecessaryCopyInitialization.cpp
@@ -16,9 +16,7 @@
 #include "clang/Basic/Diagnostic.h"
 #include <optional>
 
-namespace clang {
-namespace tidy {
-namespace performance {
+namespace clang::tidy::performance {
 namespace {
 
 using namespace ::clang::ast_matchers;
@@ -370,6 +368,4 @@ void UnnecessaryCopyInitialization::storeOptions(
                 utils::options::serializeStringList(ExcludedContainerTypes));
 }
 
-} // namespace performance
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::performance

diff  --git a/clang-tools-extra/clang-tidy/performance/UnnecessaryValueParamCheck.cpp b/clang-tools-extra/clang-tidy/performance/UnnecessaryValueParamCheck.cpp
index 6afe8fe555bf6..2fa7cd0baf98f 100644
--- a/clang-tools-extra/clang-tidy/performance/UnnecessaryValueParamCheck.cpp
+++ b/clang-tools-extra/clang-tidy/performance/UnnecessaryValueParamCheck.cpp
@@ -20,9 +20,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace performance {
+namespace clang::tidy::performance {
 
 namespace {
 
@@ -193,6 +191,4 @@ void UnnecessaryValueParamCheck::handleMoveFix(const ParmVarDecl &Var,
               SM.getFileID(CopyArgument.getBeginLoc()), "<utility>");
 }
 
-} // namespace performance
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::performance

diff  --git a/clang-tools-extra/clang-tidy/plugin/ClangTidyPlugin.cpp b/clang-tools-extra/clang-tidy/plugin/ClangTidyPlugin.cpp
index 01402f1d5f8e4..b47ce2b066c65 100644
--- a/clang-tools-extra/clang-tidy/plugin/ClangTidyPlugin.cpp
+++ b/clang-tools-extra/clang-tidy/plugin/ClangTidyPlugin.cpp
@@ -14,8 +14,7 @@
 #include "clang/Frontend/FrontendPluginRegistry.h"
 #include "clang/Frontend/MultiplexConsumer.h"
 
-namespace clang {
-namespace tidy {
+namespace clang::tidy {
 
 /// The core clang tidy plugin action. This just provides the AST consumer and
 /// command line flag parsing for using clang-tidy as a clang plugin.
@@ -75,8 +74,7 @@ class ClangTidyPluginAction : public PluginASTAction {
 private:
   std::unique_ptr<ClangTidyContext> Context;
 };
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy
 
 // This anchor is used to force the linker to link in the generated object file
 // and thus register the clang-tidy plugin.

diff  --git a/clang-tools-extra/clang-tidy/portability/PortabilityTidyModule.cpp b/clang-tools-extra/clang-tidy/portability/PortabilityTidyModule.cpp
index 1e4f1d5de1d97..b3759a754587d 100644
--- a/clang-tools-extra/clang-tidy/portability/PortabilityTidyModule.cpp
+++ b/clang-tools-extra/clang-tidy/portability/PortabilityTidyModule.cpp
@@ -13,8 +13,7 @@
 #include "SIMDIntrinsicsCheck.h"
 #include "StdAllocatorConstCheck.h"
 
-namespace clang {
-namespace tidy {
+namespace clang::tidy {
 namespace portability {
 
 class PortabilityModule : public ClangTidyModule {
@@ -39,5 +38,4 @@ static ClangTidyModuleRegistry::Add<PortabilityModule>
 // and thus register the PortabilityModule.
 volatile int PortabilityModuleAnchorSource = 0;
 
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy

diff  --git a/clang-tools-extra/clang-tidy/portability/RestrictSystemIncludesCheck.cpp b/clang-tools-extra/clang-tidy/portability/RestrictSystemIncludesCheck.cpp
index 3509cd4117dd9..9ee0b4e6d3ccb 100644
--- a/clang-tools-extra/clang-tidy/portability/RestrictSystemIncludesCheck.cpp
+++ b/clang-tools-extra/clang-tidy/portability/RestrictSystemIncludesCheck.cpp
@@ -16,9 +16,7 @@
 #include "llvm/Support/Path.h"
 #include <cstring>
 
-namespace clang {
-namespace tidy {
-namespace portability {
+namespace clang::tidy::portability {
 
 void RestrictedIncludesPPCallbacks::InclusionDirective(
     SourceLocation HashLoc, const Token &IncludeTok, StringRef FileName,
@@ -75,6 +73,4 @@ void RestrictSystemIncludesCheck::storeOptions(
   Options.store(Opts, "Includes", AllowedIncludes);
 }
 
-} // namespace portability
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::portability

diff  --git a/clang-tools-extra/clang-tidy/portability/SIMDIntrinsicsCheck.cpp b/clang-tools-extra/clang-tidy/portability/SIMDIntrinsicsCheck.cpp
index 8ea00a0b8ed6a..55ffe2d91cadb 100644
--- a/clang-tools-extra/clang-tidy/portability/SIMDIntrinsicsCheck.cpp
+++ b/clang-tools-extra/clang-tidy/portability/SIMDIntrinsicsCheck.cpp
@@ -17,9 +17,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace portability {
+namespace clang::tidy::portability {
 
 namespace {
 
@@ -146,6 +144,4 @@ void SIMDIntrinsicsCheck::check(const MatchFinder::MatchResult &Result) {
   }
 }
 
-} // namespace portability
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::portability

diff  --git a/clang-tools-extra/clang-tidy/portability/StdAllocatorConstCheck.cpp b/clang-tools-extra/clang-tidy/portability/StdAllocatorConstCheck.cpp
index a95048d71ef92..b34cb0153785d 100644
--- a/clang-tools-extra/clang-tidy/portability/StdAllocatorConstCheck.cpp
+++ b/clang-tools-extra/clang-tidy/portability/StdAllocatorConstCheck.cpp
@@ -11,9 +11,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace portability {
+namespace clang::tidy::portability {
 
 void StdAllocatorConstCheck::registerMatchers(MatchFinder *Finder) {
   // Match std::allocator<const T>.
@@ -66,6 +64,4 @@ void StdAllocatorConstCheck::check(const MatchFinder::MatchResult &Result) {
        "libraries");
 }
 
-} // namespace portability
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::portability

diff  --git a/clang-tools-extra/clang-tidy/readability/AvoidConstParamsInDecls.cpp b/clang-tools-extra/clang-tidy/readability/AvoidConstParamsInDecls.cpp
index 288a8e7d1e727..6906717dd4692 100644
--- a/clang-tools-extra/clang-tidy/readability/AvoidConstParamsInDecls.cpp
+++ b/clang-tools-extra/clang-tidy/readability/AvoidConstParamsInDecls.cpp
@@ -14,9 +14,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace readability {
+namespace clang::tidy::readability {
 namespace {
 
 SourceRange getTypeRange(const ParmVarDecl &Param) {
@@ -89,6 +87,4 @@ void AvoidConstParamsInDecls::check(const MatchFinder::MatchResult &Result) {
       CharSourceRange::getTokenRange(Tok->getLocation(), Tok->getLocation()));
 }
 
-} // namespace readability
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::readability

diff  --git a/clang-tools-extra/clang-tidy/readability/BracesAroundStatementsCheck.cpp b/clang-tools-extra/clang-tidy/readability/BracesAroundStatementsCheck.cpp
index d6f4d920b5e93..74bb073848a6c 100644
--- a/clang-tools-extra/clang-tidy/readability/BracesAroundStatementsCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/BracesAroundStatementsCheck.cpp
@@ -14,9 +14,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace readability {
+namespace clang::tidy::readability {
 
 static tok::TokenKind getTokenKind(SourceLocation Loc, const SourceManager &SM,
                                    const ASTContext *Context) {
@@ -269,6 +267,4 @@ void BracesAroundStatementsCheck::onEndOfTranslationUnit() {
   ForceBracesStmts.clear();
 }
 
-} // namespace readability
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::readability

diff  --git a/clang-tools-extra/clang-tidy/readability/ConstReturnTypeCheck.cpp b/clang-tools-extra/clang-tidy/readability/ConstReturnTypeCheck.cpp
index 557cb97ecc2cd..b63c25265d929 100644
--- a/clang-tools-extra/clang-tidy/readability/ConstReturnTypeCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/ConstReturnTypeCheck.cpp
@@ -16,9 +16,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace readability {
+namespace clang::tidy::readability {
 
 // Finds the location of the qualifying `const` token in the `FunctionDecl`'s
 // return type. Returns `std::nullopt` when the return type is not
@@ -157,6 +155,4 @@ void ConstReturnTypeCheck::check(const MatchFinder::MatchResult &Result) {
     diag(Loc, "could not transform this declaration", DiagnosticIDs::Note);
 }
 
-} // namespace readability
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::readability

diff  --git a/clang-tools-extra/clang-tidy/readability/ContainerContainsCheck.cpp b/clang-tools-extra/clang-tidy/readability/ContainerContainsCheck.cpp
index f99251df5bf47..970ed8b83e0a7 100644
--- a/clang-tools-extra/clang-tidy/readability/ContainerContainsCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/ContainerContainsCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace readability {
+namespace clang::tidy::readability {
 
 void ContainerContainsCheck::registerMatchers(MatchFinder *Finder) {
   const auto SupportedContainers = hasType(
@@ -137,6 +135,4 @@ void ContainerContainsCheck::check(const MatchFinder::MatchResult &Result) {
       CallEnd.getLocWithOffset(1), ComparisonEnd.getLocWithOffset(1)));
 }
 
-} // namespace readability
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::readability

diff  --git a/clang-tools-extra/clang-tidy/readability/ContainerDataPointerCheck.cpp b/clang-tools-extra/clang-tidy/readability/ContainerDataPointerCheck.cpp
index e22bad7db3328..5a51b2567d0aa 100644
--- a/clang-tools-extra/clang-tidy/readability/ContainerDataPointerCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/ContainerDataPointerCheck.cpp
@@ -13,9 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace readability {
+namespace clang::tidy::readability {
 
 constexpr llvm::StringLiteral ContainerExprName = "container-expr";
 constexpr llvm::StringLiteral DerefContainerExprName = "deref-container-expr";
@@ -114,6 +112,4 @@ void ContainerDataPointerCheck::check(const MatchFinder::MatchResult &Result) {
        "the address of the 0-th element")
       << Hint;
 }
-} // namespace readability
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::readability

diff  --git a/clang-tools-extra/clang-tidy/readability/ContainerSizeEmptyCheck.cpp b/clang-tools-extra/clang-tidy/readability/ContainerSizeEmptyCheck.cpp
index 56556b515abd6..a39b72e39c999 100644
--- a/clang-tools-extra/clang-tidy/readability/ContainerSizeEmptyCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/ContainerSizeEmptyCheck.cpp
@@ -90,8 +90,7 @@ AST_MATCHER(QualType, isIntegralType) {
   return Node->isIntegralType(Finder->getASTContext());
 }
 } // namespace ast_matchers
-namespace tidy {
-namespace readability {
+namespace tidy::readability {
 
 using utils::isBinaryOrTernary;
 
@@ -328,6 +327,5 @@ void ContainerSizeEmptyCheck::check(const MatchFinder::MatchResult &Result) {
       << Container;
 }
 
-} // namespace readability
-} // namespace tidy
+} // namespace tidy::readability
 } // namespace clang

diff  --git a/clang-tools-extra/clang-tidy/readability/ConvertMemberFunctionsToStatic.cpp b/clang-tools-extra/clang-tidy/readability/ConvertMemberFunctionsToStatic.cpp
index 0ff0846965f94..0ef7d2955ff76 100644
--- a/clang-tools-extra/clang-tidy/readability/ConvertMemberFunctionsToStatic.cpp
+++ b/clang-tools-extra/clang-tidy/readability/ConvertMemberFunctionsToStatic.cpp
@@ -16,9 +16,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace readability {
+namespace clang::tidy::readability {
 
 AST_MATCHER(CXXMethodDecl, isStatic) { return Node.isStatic(); }
 
@@ -167,6 +165,4 @@ void ConvertMemberFunctionsToStatic::check(
   Diag << FixItHint::CreateInsertion(Declaration->getBeginLoc(), "static ");
 }
 
-} // namespace readability
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::readability

diff  --git a/clang-tools-extra/clang-tidy/readability/DeleteNullPointerCheck.cpp b/clang-tools-extra/clang-tidy/readability/DeleteNullPointerCheck.cpp
index 9f3350409d06f..12131cc078f0b 100644
--- a/clang-tools-extra/clang-tidy/readability/DeleteNullPointerCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/DeleteNullPointerCheck.cpp
@@ -14,9 +14,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace readability {
+namespace clang::tidy::readability {
 
 void DeleteNullPointerCheck::registerMatchers(MatchFinder *Finder) {
   const auto DeleteExpr =
@@ -73,6 +71,4 @@ void DeleteNullPointerCheck::check(const MatchFinder::MatchResult &Result) {
   }
 }
 
-} // namespace readability
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::readability

diff  --git a/clang-tools-extra/clang-tidy/readability/DuplicateIncludeCheck.cpp b/clang-tools-extra/clang-tidy/readability/DuplicateIncludeCheck.cpp
index 8c69417a3cfab..d1f41e0ec79e2 100644
--- a/clang-tools-extra/clang-tidy/readability/DuplicateIncludeCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/DuplicateIncludeCheck.cpp
@@ -13,9 +13,7 @@
 #include "llvm/ADT/SmallVector.h"
 #include <memory>
 
-namespace clang {
-namespace tidy {
-namespace readability {
+namespace clang::tidy::readability {
 
 static SourceLocation advanceBeyondCurrentLine(const SourceManager &SM,
                                                SourceLocation Start,
@@ -111,6 +109,4 @@ void DuplicateIncludeCheck::registerPPCallbacks(
   PP->addPPCallbacks(std::make_unique<DuplicateIncludeCallbacks>(*this, SM));
 }
 
-} // namespace readability
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::readability

diff  --git a/clang-tools-extra/clang-tidy/readability/ElseAfterReturnCheck.cpp b/clang-tools-extra/clang-tidy/readability/ElseAfterReturnCheck.cpp
index e60f5bf804d39..1e85caf688355 100644
--- a/clang-tools-extra/clang-tidy/readability/ElseAfterReturnCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/ElseAfterReturnCheck.cpp
@@ -16,9 +16,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace readability {
+namespace clang::tidy::readability {
 
 namespace {
 
@@ -324,6 +322,4 @@ void ElseAfterReturnCheck::check(const MatchFinder::MatchResult &Result) {
   removeElseAndBrackets(Diag, *Result.Context, Else, ElseLoc);
 }
 
-} // namespace readability
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::readability

diff  --git a/clang-tools-extra/clang-tidy/readability/FunctionCognitiveComplexityCheck.cpp b/clang-tools-extra/clang-tidy/readability/FunctionCognitiveComplexityCheck.cpp
index f1e252e4ba58e..b5dc09c5f13ad 100644
--- a/clang-tools-extra/clang-tidy/readability/FunctionCognitiveComplexityCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/FunctionCognitiveComplexityCheck.cpp
@@ -33,9 +33,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace readability {
+namespace clang::tidy::readability {
 namespace {
 
 struct CognitiveComplexity final {
@@ -562,6 +560,4 @@ void FunctionCognitiveComplexityCheck::check(
   }
 }
 
-} // namespace readability
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::readability

diff  --git a/clang-tools-extra/clang-tidy/readability/FunctionSizeCheck.cpp b/clang-tools-extra/clang-tidy/readability/FunctionSizeCheck.cpp
index 96b81235eee85..3c803959caf80 100644
--- a/clang-tools-extra/clang-tidy/readability/FunctionSizeCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/FunctionSizeCheck.cpp
@@ -13,9 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace readability {
+namespace clang::tidy::readability {
 namespace {
 
 class FunctionASTVisitor : public RecursiveASTVisitor<FunctionASTVisitor> {
@@ -221,6 +219,4 @@ void FunctionSizeCheck::check(const MatchFinder::MatchResult &Result) {
   }
 }
 
-} // namespace readability
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::readability

diff  --git a/clang-tools-extra/clang-tidy/readability/IdentifierLengthCheck.cpp b/clang-tools-extra/clang-tidy/readability/IdentifierLengthCheck.cpp
index 1fd8624fcf4b2..68da28b7f1a3c 100644
--- a/clang-tools-extra/clang-tidy/readability/IdentifierLengthCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/IdentifierLengthCheck.cpp
@@ -14,9 +14,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace readability {
+namespace clang::tidy::readability {
 
 const unsigned DefaultMinimumVariableNameLength = 3;
 const unsigned DefaultMinimumLoopCounterNameLength = 2;
@@ -151,6 +149,4 @@ void IdentifierLengthCheck::check(const MatchFinder::MatchResult &Result) {
   }
 }
 
-} // namespace readability
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::readability

diff  --git a/clang-tools-extra/clang-tidy/readability/IdentifierNamingCheck.cpp b/clang-tools-extra/clang-tidy/readability/IdentifierNamingCheck.cpp
index 47a55d3439a48..b2b2875731874 100644
--- a/clang-tools-extra/clang-tidy/readability/IdentifierNamingCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/IdentifierNamingCheck.cpp
@@ -28,8 +28,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
+namespace clang::tidy {
 
 llvm::ArrayRef<
     std::pair<readability::IdentifierNamingCheck::CaseType, StringRef>>
@@ -1451,5 +1450,4 @@ IdentifierNamingCheck::getStyleForFile(StringRef FileName) const {
 }
 
 } // namespace readability
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy

diff  --git a/clang-tools-extra/clang-tidy/readability/ImplicitBoolConversionCheck.cpp b/clang-tools-extra/clang-tidy/readability/ImplicitBoolConversionCheck.cpp
index 51e3e2c1260b1..7ec63d0fd9edf 100644
--- a/clang-tools-extra/clang-tidy/readability/ImplicitBoolConversionCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/ImplicitBoolConversionCheck.cpp
@@ -15,9 +15,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace readability {
+namespace clang::tidy::readability {
 
 namespace {
 
@@ -391,6 +389,4 @@ void ImplicitBoolConversionCheck::handleCastFromBool(
   }
 }
 
-} // namespace readability
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::readability

diff  --git a/clang-tools-extra/clang-tidy/readability/InconsistentDeclarationParameterNameCheck.cpp b/clang-tools-extra/clang-tidy/readability/InconsistentDeclarationParameterNameCheck.cpp
index c43c2b5a0560c..13031e7cc14b5 100644
--- a/clang-tools-extra/clang-tidy/readability/InconsistentDeclarationParameterNameCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/InconsistentDeclarationParameterNameCheck.cpp
@@ -15,9 +15,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace readability {
+namespace clang::tidy::readability {
 
 namespace {
 
@@ -350,6 +348,4 @@ void InconsistentDeclarationParameterNameCheck::markRedeclarationsAsVisited(
   }
 }
 
-} // namespace readability
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::readability

diff  --git a/clang-tools-extra/clang-tidy/readability/IsolateDeclarationCheck.cpp b/clang-tools-extra/clang-tidy/readability/IsolateDeclarationCheck.cpp
index 1a4c6ff83b6ac..97abf8d9ecca6 100644
--- a/clang-tools-extra/clang-tidy/readability/IsolateDeclarationCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/IsolateDeclarationCheck.cpp
@@ -14,9 +14,7 @@
 using namespace clang::ast_matchers;
 using namespace clang::tidy::utils::lexer;
 
-namespace clang {
-namespace tidy {
-namespace readability {
+namespace clang::tidy::readability {
 
 namespace {
 AST_MATCHER(DeclStmt, isSingleDecl) { return Node.isSingleDecl(); }
@@ -273,6 +271,4 @@ void IsolateDeclarationCheck::check(const MatchFinder::MatchResult &Result) {
   Diag << FixItHint::CreateReplacement(WholeDecl->getSourceRange(),
                                        Replacement);
 }
-} // namespace readability
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::readability

diff  --git a/clang-tools-extra/clang-tidy/readability/MagicNumbersCheck.cpp b/clang-tools-extra/clang-tidy/readability/MagicNumbersCheck.cpp
index 1d15ae19ead4d..64940ede8e1c7 100644
--- a/clang-tools-extra/clang-tidy/readability/MagicNumbersCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/MagicNumbersCheck.cpp
@@ -54,8 +54,7 @@ static bool isUsedToDefineABitField(const MatchFinder::MatchResult &Result,
                       });
 }
 
-namespace tidy {
-namespace readability {
+namespace tidy::readability {
 
 const char DefaultIgnoredIntegerValues[] = "1;2;3;4;";
 const char DefaultIgnoredFloatingPointValues[] = "1.0;100.0;";
@@ -225,6 +224,5 @@ bool MagicNumbersCheck::isBitFieldWidth(
                       });
 }
 
-} // namespace readability
-} // namespace tidy
+} // namespace tidy::readability
 } // namespace clang

diff  --git a/clang-tools-extra/clang-tidy/readability/MakeMemberFunctionConstCheck.cpp b/clang-tools-extra/clang-tidy/readability/MakeMemberFunctionConstCheck.cpp
index 15ab394eeee11..2d6a469252425 100644
--- a/clang-tools-extra/clang-tidy/readability/MakeMemberFunctionConstCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/MakeMemberFunctionConstCheck.cpp
@@ -15,9 +15,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace readability {
+namespace clang::tidy::readability {
 
 AST_MATCHER(CXXMethodDecl, isStatic) { return Node.isStatic(); }
 
@@ -267,6 +265,4 @@ void MakeMemberFunctionConstCheck::check(
   }
 }
 
-} // namespace readability
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::readability

diff  --git a/clang-tools-extra/clang-tidy/readability/MisleadingIndentationCheck.cpp b/clang-tools-extra/clang-tidy/readability/MisleadingIndentationCheck.cpp
index 7b5a22f449c4b..4c10b6f6eebe0 100644
--- a/clang-tools-extra/clang-tidy/readability/MisleadingIndentationCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/MisleadingIndentationCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace readability {
+namespace clang::tidy::readability {
 
 static const IfStmt *getPrecedingIf(const SourceManager &SM,
                                     ASTContext *Context, const IfStmt *If) {
@@ -121,6 +119,4 @@ void MisleadingIndentationCheck::check(const MatchFinder::MatchResult &Result) {
     missingBracesCheck(*Result.SourceManager, CStmt);
 }
 
-} // namespace readability
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::readability

diff  --git a/clang-tools-extra/clang-tidy/readability/MisplacedArrayIndexCheck.cpp b/clang-tools-extra/clang-tidy/readability/MisplacedArrayIndexCheck.cpp
index 5cc4b963b30fb..328d1896ce9f8 100644
--- a/clang-tools-extra/clang-tidy/readability/MisplacedArrayIndexCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/MisplacedArrayIndexCheck.cpp
@@ -14,9 +14,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace readability {
+namespace clang::tidy::readability {
 
 void MisplacedArrayIndexCheck::registerMatchers(MatchFinder *Finder) {
   Finder->addMatcher(
@@ -52,6 +50,4 @@ void MisplacedArrayIndexCheck::check(const MatchFinder::MatchResult &Result) {
       ArraySubscriptE->getRHS()->getSourceRange(), LText);
 }
 
-} // namespace readability
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::readability

diff  --git a/clang-tools-extra/clang-tidy/readability/NamedParameterCheck.cpp b/clang-tools-extra/clang-tidy/readability/NamedParameterCheck.cpp
index c8a8edf67884e..f621cfe706859 100644
--- a/clang-tools-extra/clang-tidy/readability/NamedParameterCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/NamedParameterCheck.cpp
@@ -13,9 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace readability {
+namespace clang::tidy::readability {
 
 void NamedParameterCheck::registerMatchers(ast_matchers::MatchFinder *Finder) {
   Finder->addMatcher(functionDecl().bind("decl"), this);
@@ -117,6 +115,4 @@ void NamedParameterCheck::check(const MatchFinder::MatchResult &Result) {
   }
 }
 
-} // namespace readability
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::readability

diff  --git a/clang-tools-extra/clang-tidy/readability/NamespaceCommentCheck.cpp b/clang-tools-extra/clang-tidy/readability/NamespaceCommentCheck.cpp
index 270a527ba7627..ad2d396311ed2 100644
--- a/clang-tools-extra/clang-tidy/readability/NamespaceCommentCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/NamespaceCommentCheck.cpp
@@ -18,9 +18,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace readability {
+namespace clang::tidy::readability {
 
 NamespaceCommentCheck::NamespaceCommentCheck(StringRef Name,
                                              ClangTidyContext *Context)
@@ -204,6 +202,4 @@ void NamespaceCommentCheck::check(const MatchFinder::MatchResult &Result) {
       << NamespaceNameForDiag;
 }
 
-} // namespace readability
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::readability

diff  --git a/clang-tools-extra/clang-tidy/readability/NonConstParameterCheck.cpp b/clang-tools-extra/clang-tidy/readability/NonConstParameterCheck.cpp
index 01bcfca356087..974909f3ab35a 100644
--- a/clang-tools-extra/clang-tidy/readability/NonConstParameterCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/NonConstParameterCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace readability {
+namespace clang::tidy::readability {
 
 void NonConstParameterCheck::registerMatchers(MatchFinder *Finder) {
   // Add parameters to Parameters.
@@ -233,6 +231,4 @@ void NonConstParameterCheck::markCanNotBeConst(const Expr *E,
   }
 }
 
-} // namespace readability
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::readability

diff  --git a/clang-tools-extra/clang-tidy/readability/QualifiedAutoCheck.cpp b/clang-tools-extra/clang-tidy/readability/QualifiedAutoCheck.cpp
index 563976d152087..e843c593a92cc 100644
--- a/clang-tools-extra/clang-tidy/readability/QualifiedAutoCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/QualifiedAutoCheck.cpp
@@ -14,9 +14,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace readability {
+namespace clang::tidy::readability {
 
 namespace {
 
@@ -286,6 +284,4 @@ void QualifiedAutoCheck::check(const MatchFinder::MatchResult &Result) {
   }
 }
 
-} // namespace readability
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::readability

diff  --git a/clang-tools-extra/clang-tidy/readability/ReadabilityTidyModule.cpp b/clang-tools-extra/clang-tidy/readability/ReadabilityTidyModule.cpp
index 6bbef6b7fa07c..7aa090424257d 100644
--- a/clang-tools-extra/clang-tidy/readability/ReadabilityTidyModule.cpp
+++ b/clang-tools-extra/clang-tidy/readability/ReadabilityTidyModule.cpp
@@ -52,8 +52,7 @@
 #include "UppercaseLiteralSuffixCheck.h"
 #include "UseAnyOfAllOfCheck.h"
 
-namespace clang {
-namespace tidy {
+namespace clang::tidy {
 namespace readability {
 
 class ReadabilityModule : public ClangTidyModule {
@@ -156,5 +155,4 @@ static ClangTidyModuleRegistry::Add<ReadabilityModule>
 // and thus register the ReadabilityModule.
 volatile int ReadabilityModuleAnchorSource = 0;
 
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy

diff  --git a/clang-tools-extra/clang-tidy/readability/RedundantAccessSpecifiersCheck.cpp b/clang-tools-extra/clang-tidy/readability/RedundantAccessSpecifiersCheck.cpp
index cf7fc03bc58e4..c3464b2a83d15 100644
--- a/clang-tools-extra/clang-tidy/readability/RedundantAccessSpecifiersCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/RedundantAccessSpecifiersCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace readability {
+namespace clang::tidy::readability {
 
 void RedundantAccessSpecifiersCheck::registerMatchers(MatchFinder *Finder) {
   Finder->addMatcher(
@@ -77,6 +75,4 @@ void RedundantAccessSpecifiersCheck::check(
   }
 }
 
-} // namespace readability
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::readability

diff  --git a/clang-tools-extra/clang-tidy/readability/RedundantControlFlowCheck.cpp b/clang-tools-extra/clang-tidy/readability/RedundantControlFlowCheck.cpp
index dd63de3f048e1..ed01d3a2d7a71 100644
--- a/clang-tools-extra/clang-tidy/readability/RedundantControlFlowCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/RedundantControlFlowCheck.cpp
@@ -13,9 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace readability {
+namespace clang::tidy::readability {
 
 namespace {
 
@@ -91,6 +89,4 @@ void RedundantControlFlowCheck::issueDiagnostic(
   diag(StmtRange.getBegin(), Diag) << FixItHint::CreateRemoval(RemovedRange);
 }
 
-} // namespace readability
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::readability

diff  --git a/clang-tools-extra/clang-tidy/readability/RedundantDeclarationCheck.cpp b/clang-tools-extra/clang-tidy/readability/RedundantDeclarationCheck.cpp
index 78ba9691c2557..f21f0a785689f 100644
--- a/clang-tools-extra/clang-tidy/readability/RedundantDeclarationCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/RedundantDeclarationCheck.cpp
@@ -13,9 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace readability {
+namespace clang::tidy::readability {
 
 AST_MATCHER(FunctionDecl, doesDeclarationForceExternallyVisibleDefinition) {
   return Node.doesDeclarationForceExternallyVisibleDefinition();
@@ -86,6 +84,4 @@ void RedundantDeclarationCheck::check(const MatchFinder::MatchResult &Result) {
   }
   diag(Prev->getLocation(), "previously declared here", DiagnosticIDs::Note);
 }
-} // namespace readability
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::readability

diff  --git a/clang-tools-extra/clang-tidy/readability/RedundantFunctionPtrDereferenceCheck.cpp b/clang-tools-extra/clang-tidy/readability/RedundantFunctionPtrDereferenceCheck.cpp
index 17613785fac06..247d287be2b36 100644
--- a/clang-tools-extra/clang-tidy/readability/RedundantFunctionPtrDereferenceCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/RedundantFunctionPtrDereferenceCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace readability {
+namespace clang::tidy::readability {
 
 void RedundantFunctionPtrDereferenceCheck::registerMatchers(MatchFinder *Finder) {
   Finder->addMatcher(
@@ -32,6 +30,4 @@ void RedundantFunctionPtrDereferenceCheck::check(const MatchFinder::MatchResult
       << FixItHint::CreateRemoval(Operator->getOperatorLoc());
 }
 
-} // namespace readability
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::readability

diff  --git a/clang-tools-extra/clang-tidy/readability/RedundantMemberInitCheck.cpp b/clang-tools-extra/clang-tidy/readability/RedundantMemberInitCheck.cpp
index 0af9a0478ab9b..b5d407773bb73 100644
--- a/clang-tools-extra/clang-tidy/readability/RedundantMemberInitCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/RedundantMemberInitCheck.cpp
@@ -16,9 +16,7 @@
 using namespace clang::ast_matchers;
 using namespace clang::tidy::matchers;
 
-namespace clang {
-namespace tidy {
-namespace readability {
+namespace clang::tidy::readability {
 
 void RedundantMemberInitCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
   Options.store(Opts, "IgnoreBaseInCopyConstructors",
@@ -69,6 +67,4 @@ void RedundantMemberInitCheck::check(const MatchFinder::MatchResult &Result) {
   }
 }
 
-} // namespace readability
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::readability

diff  --git a/clang-tools-extra/clang-tidy/readability/RedundantPreprocessorCheck.cpp b/clang-tools-extra/clang-tidy/readability/RedundantPreprocessorCheck.cpp
index 0ce2cf2c35755..513687f03df0c 100644
--- a/clang-tools-extra/clang-tidy/readability/RedundantPreprocessorCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/RedundantPreprocessorCheck.cpp
@@ -12,9 +12,7 @@
 #include "clang/Lex/PPCallbacks.h"
 #include "clang/Lex/Preprocessor.h"
 
-namespace clang {
-namespace tidy {
-namespace readability {
+namespace clang::tidy::readability {
 
 namespace {
 /// Information about an opening preprocessor directive.
@@ -104,6 +102,4 @@ void RedundantPreprocessorCheck::registerPPCallbacks(
       ::std::make_unique<RedundantPreprocessorCallbacks>(*this, *PP));
 }
 
-} // namespace readability
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::readability

diff  --git a/clang-tools-extra/clang-tidy/readability/RedundantSmartptrGetCheck.cpp b/clang-tools-extra/clang-tidy/readability/RedundantSmartptrGetCheck.cpp
index e663f055f30d2..8837ac16e8828 100644
--- a/clang-tools-extra/clang-tidy/readability/RedundantSmartptrGetCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/RedundantSmartptrGetCheck.cpp
@@ -12,9 +12,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace readability {
+namespace clang::tidy::readability {
 
 namespace {
 internal::Matcher<Expr> callToGet(const internal::Matcher<Decl> &OnClass) {
@@ -172,6 +170,4 @@ void RedundantSmartptrGetCheck::check(const MatchFinder::MatchResult &Result) {
       << FixItHint::CreateReplacement(SR, Replacement);
 }
 
-} // namespace readability
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::readability

diff  --git a/clang-tools-extra/clang-tidy/readability/RedundantStringCStrCheck.cpp b/clang-tools-extra/clang-tidy/readability/RedundantStringCStrCheck.cpp
index 9ecd6d612e0c8..960d5abcc912e 100644
--- a/clang-tools-extra/clang-tidy/readability/RedundantStringCStrCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/RedundantStringCStrCheck.cpp
@@ -16,9 +16,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace readability {
+namespace clang::tidy::readability {
 
 namespace {
 
@@ -200,6 +198,4 @@ void RedundantStringCStrCheck::check(const MatchFinder::MatchResult &Result) {
       << FixItHint::CreateReplacement(Call->getSourceRange(), ArgText);
 }
 
-} // namespace readability
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::readability

diff  --git a/clang-tools-extra/clang-tidy/readability/RedundantStringInitCheck.cpp b/clang-tools-extra/clang-tidy/readability/RedundantStringInitCheck.cpp
index 3e020377f16e4..b579aafe8ea43 100644
--- a/clang-tools-extra/clang-tidy/readability/RedundantStringInitCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/RedundantStringInitCheck.cpp
@@ -15,9 +15,7 @@
 using namespace clang::ast_matchers;
 using namespace clang::tidy::matchers;
 
-namespace clang {
-namespace tidy {
-namespace readability {
+namespace clang::tidy::readability {
 
 const char DefaultStringNames[] =
     "::std::basic_string_view;::std::basic_string";
@@ -162,6 +160,4 @@ void RedundantStringInitCheck::check(const MatchFinder::MatchResult &Result) {
   }
 }
 
-} // namespace readability
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::readability

diff  --git a/clang-tools-extra/clang-tidy/readability/SimplifyBooleanExprCheck.cpp b/clang-tools-extra/clang-tidy/readability/SimplifyBooleanExprCheck.cpp
index 18a3bf6aa6397..07cb07f053729 100644
--- a/clang-tools-extra/clang-tidy/readability/SimplifyBooleanExprCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/SimplifyBooleanExprCheck.cpp
@@ -17,9 +17,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace readability {
+namespace clang::tidy::readability {
 
 namespace {
 
@@ -957,6 +955,4 @@ bool SimplifyBooleanExprCheck::reportDeMorgan(const ASTContext &Context,
   Diag << Fixes;
   return true;
 }
-} // namespace readability
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::readability

diff  --git a/clang-tools-extra/clang-tidy/readability/SimplifySubscriptExprCheck.cpp b/clang-tools-extra/clang-tidy/readability/SimplifySubscriptExprCheck.cpp
index d77b4368527c5..d274abcbfabe8 100644
--- a/clang-tools-extra/clang-tidy/readability/SimplifySubscriptExprCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/SimplifySubscriptExprCheck.cpp
@@ -13,9 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace readability {
+namespace clang::tidy::readability {
 
 static const char KDefaultTypes[] =
     "::std::basic_string;::std::basic_string_view;::std::vector;::std::array";
@@ -66,6 +64,4 @@ void SimplifySubscriptExprCheck::storeOptions(
   Options.store(Opts, "Types", utils::options::serializeStringList(Types));
 }
 
-} // namespace readability
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::readability

diff  --git a/clang-tools-extra/clang-tidy/readability/StaticAccessedThroughInstanceCheck.cpp b/clang-tools-extra/clang-tidy/readability/StaticAccessedThroughInstanceCheck.cpp
index 0f73b1320de5a..b23b67e6261d0 100644
--- a/clang-tools-extra/clang-tidy/readability/StaticAccessedThroughInstanceCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/StaticAccessedThroughInstanceCheck.cpp
@@ -13,9 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace readability {
+namespace clang::tidy::readability {
 
 static unsigned getNameSpecifierNestingLevel(const QualType &QType) {
   if (const ElaboratedType *ElType = QType->getAs<ElaboratedType>()) {
@@ -94,6 +92,4 @@ void StaticAccessedThroughInstanceCheck::check(
       BaseTypeName + "::");
 }
 
-} // namespace readability
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::readability

diff  --git a/clang-tools-extra/clang-tidy/readability/StaticDefinitionInAnonymousNamespaceCheck.cpp b/clang-tools-extra/clang-tidy/readability/StaticDefinitionInAnonymousNamespaceCheck.cpp
index ffd1238e421c3..3e6bb01b55f9c 100644
--- a/clang-tools-extra/clang-tidy/readability/StaticDefinitionInAnonymousNamespaceCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/StaticDefinitionInAnonymousNamespaceCheck.cpp
@@ -13,9 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace readability {
+namespace clang::tidy::readability {
 
 void StaticDefinitionInAnonymousNamespaceCheck::registerMatchers(
     MatchFinder *Finder) {
@@ -60,6 +58,4 @@ void StaticDefinitionInAnonymousNamespaceCheck::check(
   }
 }
 
-} // namespace readability
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::readability

diff  --git a/clang-tools-extra/clang-tidy/readability/StringCompareCheck.cpp b/clang-tools-extra/clang-tidy/readability/StringCompareCheck.cpp
index d3cf27d1fc3f4..3b5d89c8c6471 100644
--- a/clang-tools-extra/clang-tidy/readability/StringCompareCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/StringCompareCheck.cpp
@@ -14,9 +14,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace readability {
+namespace clang::tidy::readability {
 
 static const StringRef CompareMessage = "do not use 'compare' to test equality "
                                         "of strings; use the string equality "
@@ -75,6 +73,4 @@ void StringCompareCheck::check(const MatchFinder::MatchResult &Result) {
   // FIXME: Add fixit to fix the code for case one and two (match1).
 }
 
-} // namespace readability
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::readability

diff  --git a/clang-tools-extra/clang-tidy/readability/SuspiciousCallArgumentCheck.cpp b/clang-tools-extra/clang-tidy/readability/SuspiciousCallArgumentCheck.cpp
index 3972dc3d4d48f..7fe0c0982dc30 100644
--- a/clang-tools-extra/clang-tidy/readability/SuspiciousCallArgumentCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/SuspiciousCallArgumentCheck.cpp
@@ -17,9 +17,7 @@
 using namespace clang::ast_matchers;
 namespace optutils = clang::tidy::utils::options;
 
-namespace clang {
-namespace tidy {
-namespace readability {
+namespace clang::tidy::readability {
 
 namespace {
 struct DefaultHeuristicConfiguration {
@@ -807,6 +805,4 @@ bool SuspiciousCallArgumentCheck::areNamesSimilar(StringRef Arg,
   llvm_unreachable("Unhandled heuristic kind");
 }
 
-} // namespace readability
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::readability

diff  --git a/clang-tools-extra/clang-tidy/readability/UniqueptrDeleteReleaseCheck.cpp b/clang-tools-extra/clang-tidy/readability/UniqueptrDeleteReleaseCheck.cpp
index 23f8dbbacb685..462085b023179 100644
--- a/clang-tools-extra/clang-tidy/readability/UniqueptrDeleteReleaseCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/UniqueptrDeleteReleaseCheck.cpp
@@ -15,9 +15,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace readability {
+namespace clang::tidy::readability {
 
 void UniqueptrDeleteReleaseCheck::storeOptions(
     ClangTidyOptions::OptionMap &Opts) {
@@ -81,6 +79,4 @@ void UniqueptrDeleteReleaseCheck::check(
   }
 }
 
-} // namespace readability
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::readability

diff  --git a/clang-tools-extra/clang-tidy/readability/UppercaseLiteralSuffixCheck.cpp b/clang-tools-extra/clang-tidy/readability/UppercaseLiteralSuffixCheck.cpp
index e665bcd3200b1..549331c2d9938 100644
--- a/clang-tools-extra/clang-tidy/readability/UppercaseLiteralSuffixCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/UppercaseLiteralSuffixCheck.cpp
@@ -17,9 +17,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace readability {
+namespace clang::tidy::readability {
 
 namespace {
 
@@ -241,6 +239,4 @@ void UppercaseLiteralSuffixCheck::check(
   checkBoundMatch<FloatingLiteralCheck>(Result);
 }
 
-} // namespace readability
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::readability

diff  --git a/clang-tools-extra/clang-tidy/readability/UseAnyOfAllOfCheck.cpp b/clang-tools-extra/clang-tidy/readability/UseAnyOfAllOfCheck.cpp
index 564e2cae3ecb6..7cf0e0853f080 100644
--- a/clang-tools-extra/clang-tidy/readability/UseAnyOfAllOfCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/UseAnyOfAllOfCheck.cpp
@@ -37,8 +37,7 @@ AST_MATCHER_P(Stmt, nextStmt, ast_matchers::internal::Matcher<Stmt>,
 }
 } // namespace
 
-namespace tidy {
-namespace readability {
+namespace tidy::readability {
 
 void UseAnyOfAllOfCheck::registerMatchers(MatchFinder *Finder) {
   auto Returns = [](bool V) {
@@ -104,6 +103,5 @@ void UseAnyOfAllOfCheck::check(const MatchFinder::MatchResult &Result) {
   }
 }
 
-} // namespace readability
-} // namespace tidy
+} // namespace tidy::readability
 } // namespace clang

diff  --git a/clang-tools-extra/clang-tidy/rename_check.py b/clang-tools-extra/clang-tidy/rename_check.py
index 4bb9af8cbe0a8..ab37007ca0143 100755
--- a/clang-tools-extra/clang-tidy/rename_check.py
+++ b/clang-tools-extra/clang-tidy/rename_check.py
@@ -308,8 +308,9 @@ def main():
     for filename in check_implementation_files:
       # Move check implementation to the directory of the new module.
       filename = fileRename(filename, old_module_path, new_module_path)
-      replaceInFileRegex(filename, 'namespace ' + old_module + '[^ \n]*',
-                         'namespace ' + new_namespace)
+      replaceInFileRegex(filename,
+                         'namespace clang::tidy::' + old_module + '[^ \n]*',
+                         'namespace clang::tidy::' + new_namespace)
 
   if (args.old_check_name == args.new_check_name):
     return

diff  --git a/clang-tools-extra/clang-tidy/tool/ClangTidyMain.cpp b/clang-tools-extra/clang-tidy/tool/ClangTidyMain.cpp
index 3ff4cbdad4dac..765b8483561ea 100644
--- a/clang-tools-extra/clang-tidy/tool/ClangTidyMain.cpp
+++ b/clang-tools-extra/clang-tidy/tool/ClangTidyMain.cpp
@@ -263,8 +263,7 @@ option is recognized.
 )"),
                                   cl::init(false), cl::cat(ClangTidyCategory));
 
-namespace clang {
-namespace tidy {
+namespace clang::tidy {
 
 static void printStats(const ClangTidyStats &Stats) {
   if (Stats.errorsIgnored()) {
@@ -660,5 +659,4 @@ int clangTidyMain(int argc, const char **argv) {
   return 0;
 }
 
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy

diff  --git a/clang-tools-extra/clang-tidy/utils/ASTUtils.cpp b/clang-tools-extra/clang-tidy/utils/ASTUtils.cpp
index b226e25221151..9fda73e9047bb 100644
--- a/clang-tools-extra/clang-tidy/utils/ASTUtils.cpp
+++ b/clang-tools-extra/clang-tidy/utils/ASTUtils.cpp
@@ -12,9 +12,7 @@
 #include "clang/ASTMatchers/ASTMatchers.h"
 #include "clang/Lex/Lexer.h"
 
-namespace clang {
-namespace tidy {
-namespace utils {
+namespace clang::tidy::utils {
 using namespace ast_matchers;
 
 const FunctionDecl *getSurroundingFunction(ASTContext &Context,
@@ -90,6 +88,4 @@ bool rangeCanBeFixed(SourceRange Range, const SourceManager *SM) {
          !utils::rangeContainsMacroExpansion(Range, SM);
 }
 
-} // namespace utils
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::utils

diff  --git a/clang-tools-extra/clang-tidy/utils/Aliasing.cpp b/clang-tools-extra/clang-tidy/utils/Aliasing.cpp
index c272453761a6b..2facf0625605e 100644
--- a/clang-tools-extra/clang-tidy/utils/Aliasing.cpp
+++ b/clang-tools-extra/clang-tidy/utils/Aliasing.cpp
@@ -11,9 +11,7 @@
 #include "clang/AST/Expr.h"
 #include "clang/AST/ExprCXX.h"
 
-namespace clang {
-namespace tidy {
-namespace utils {
+namespace clang::tidy::utils {
 
 /// Return whether \p S is a reference to the declaration of \p Var.
 static bool isAccessForVar(const Stmt *S, const VarDecl *Var) {
@@ -96,6 +94,4 @@ bool hasPtrOrReferenceInFunc(const Decl *Func, const VarDecl *Var) {
          refersToEnclosingLambdaCaptureByRef(Func, Var);
 }
 
-} // namespace utils
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::utils

diff  --git a/clang-tools-extra/clang-tidy/utils/DeclRefExprUtils.cpp b/clang-tools-extra/clang-tidy/utils/DeclRefExprUtils.cpp
index 2df0461486963..891529997787d 100644
--- a/clang-tools-extra/clang-tidy/utils/DeclRefExprUtils.cpp
+++ b/clang-tools-extra/clang-tidy/utils/DeclRefExprUtils.cpp
@@ -12,10 +12,7 @@
 #include "clang/AST/DeclCXX.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 
-namespace clang {
-namespace tidy {
-namespace utils {
-namespace decl_ref_expr {
+namespace clang::tidy::utils::decl_ref_expr {
 
 using namespace ::clang::ast_matchers;
 using llvm::SmallPtrSet;
@@ -146,7 +143,4 @@ bool isCopyAssignmentArgument(const DeclRefExpr &DeclRef, const Decl &Decl,
   return !Matches.empty();
 }
 
-} // namespace decl_ref_expr
-} // namespace utils
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::utils::decl_ref_expr

diff  --git a/clang-tools-extra/clang-tidy/utils/ExceptionAnalyzer.cpp b/clang-tools-extra/clang-tidy/utils/ExceptionAnalyzer.cpp
index 1f22c1d936561..359e7e9dc46af 100644
--- a/clang-tools-extra/clang-tidy/utils/ExceptionAnalyzer.cpp
+++ b/clang-tools-extra/clang-tidy/utils/ExceptionAnalyzer.cpp
@@ -8,9 +8,7 @@
 
 #include "ExceptionAnalyzer.h"
 
-namespace clang {
-namespace tidy {
-namespace utils {
+namespace clang::tidy::utils {
 
 void ExceptionAnalyzer::ExceptionInfo::registerException(
     const Type *ExceptionType) {
@@ -274,7 +272,4 @@ ExceptionAnalyzer::analyze(const Stmt *Stmt) {
   return analyzeDispatch(Stmt);
 }
 
-} // namespace utils
-} // namespace tidy
-
-} // namespace clang
+} // namespace clang::tidy::utils

diff  --git a/clang-tools-extra/clang-tidy/utils/ExprSequence.cpp b/clang-tools-extra/clang-tidy/utils/ExprSequence.cpp
index ae10be607a2f2..beb4c44467a80 100644
--- a/clang-tools-extra/clang-tidy/utils/ExprSequence.cpp
+++ b/clang-tools-extra/clang-tidy/utils/ExprSequence.cpp
@@ -10,9 +10,7 @@
 #include "clang/AST/ParentMapContext.h"
 #include <optional>
 
-namespace clang {
-namespace tidy {
-namespace utils {
+namespace clang::tidy::utils {
 
 // Returns the Stmt nodes that are parents of 'S', skipping any potential
 // intermediate non-Stmt nodes.
@@ -206,6 +204,4 @@ const CFGBlock *StmtToBlockMap::blockContainingStmt(const Stmt *S) const {
   return Map.lookup(S);
 }
 
-} // namespace utils
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::utils

diff  --git a/clang-tools-extra/clang-tidy/utils/FileExtensionsUtils.cpp b/clang-tools-extra/clang-tidy/utils/FileExtensionsUtils.cpp
index 4e01409d49762..e8844281e0309 100644
--- a/clang-tools-extra/clang-tidy/utils/FileExtensionsUtils.cpp
+++ b/clang-tools-extra/clang-tidy/utils/FileExtensionsUtils.cpp
@@ -11,9 +11,7 @@
 #include "llvm/Support/Path.h"
 #include <optional>
 
-namespace clang {
-namespace tidy {
-namespace utils {
+namespace clang::tidy::utils {
 
 bool isExpansionLocInHeaderFile(SourceLocation Loc, const SourceManager &SM,
                                 const FileExtensionsSet &HeaderFileExtensions) {
@@ -70,6 +68,4 @@ bool isFileExtension(StringRef FileName,
   return getFileExtension(FileName, FileExtensions).has_value();
 }
 
-} // namespace utils
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::utils

diff  --git a/clang-tools-extra/clang-tidy/utils/FixItHintUtils.cpp b/clang-tools-extra/clang-tidy/utils/FixItHintUtils.cpp
index 62ba137723231..4f11c9b7d047d 100644
--- a/clang-tools-extra/clang-tidy/utils/FixItHintUtils.cpp
+++ b/clang-tools-extra/clang-tidy/utils/FixItHintUtils.cpp
@@ -12,10 +12,7 @@
 #include "clang/AST/Type.h"
 #include <optional>
 
-namespace clang {
-namespace tidy {
-namespace utils {
-namespace fixit {
+namespace clang::tidy::utils::fixit {
 
 FixItHint changeVarDeclToReference(const VarDecl &Var, ASTContext &Context) {
   SourceLocation AmpLocation = Var.getLocation();
@@ -224,7 +221,4 @@ std::optional<FixItHint> addQualifierToVarDecl(const VarDecl &Var,
 
   return std::nullopt;
 }
-} // namespace fixit
-} // namespace utils
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::utils::fixit

diff  --git a/clang-tools-extra/clang-tidy/utils/HeaderGuard.cpp b/clang-tools-extra/clang-tidy/utils/HeaderGuard.cpp
index c5d5004fb4df1..46c36d62bdd56 100644
--- a/clang-tools-extra/clang-tidy/utils/HeaderGuard.cpp
+++ b/clang-tools-extra/clang-tidy/utils/HeaderGuard.cpp
@@ -13,9 +13,7 @@
 #include "clang/Tooling/Tooling.h"
 #include "llvm/Support/Path.h"
 
-namespace clang {
-namespace tidy {
-namespace utils {
+namespace clang::tidy::utils {
 
 /// canonicalize a path by removing ./ and ../ components.
 static std::string cleanPath(StringRef Path) {
@@ -298,6 +296,4 @@ bool HeaderGuardCheck::shouldSuggestToAddHeaderGuard(StringRef FileName) {
 std::string HeaderGuardCheck::formatEndIf(StringRef HeaderGuard) {
   return "endif // " + HeaderGuard.str();
 }
-} // namespace utils
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::utils

diff  --git a/clang-tools-extra/clang-tidy/utils/IncludeInserter.cpp b/clang-tools-extra/clang-tidy/utils/IncludeInserter.cpp
index 58afc47fc69e2..d0b7474992abd 100644
--- a/clang-tools-extra/clang-tidy/utils/IncludeInserter.cpp
+++ b/clang-tools-extra/clang-tidy/utils/IncludeInserter.cpp
@@ -12,9 +12,7 @@
 #include "clang/Lex/Token.h"
 #include <optional>
 
-namespace clang {
-namespace tidy {
-namespace utils {
+namespace clang::tidy::utils {
 
 class IncludeInserterCallback : public PPCallbacks {
 public:
@@ -99,6 +97,4 @@ void IncludeInserter::addInclude(StringRef FileName, bool IsAngled,
   getOrCreate(FileID).addInclude(FileName, IsAngled, HashLocation, EndLocation);
 }
 
-} // namespace utils
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::utils

diff  --git a/clang-tools-extra/clang-tidy/utils/IncludeSorter.cpp b/clang-tools-extra/clang-tidy/utils/IncludeSorter.cpp
index 1ce110e797f99..95dbdbb081392 100644
--- a/clang-tools-extra/clang-tidy/utils/IncludeSorter.cpp
+++ b/clang-tools-extra/clang-tidy/utils/IncludeSorter.cpp
@@ -12,8 +12,7 @@
 #include <algorithm>
 #include <optional>
 
-namespace clang {
-namespace tidy {
+namespace clang::tidy {
 namespace utils {
 
 namespace {
@@ -233,5 +232,4 @@ OptionEnumMapping<utils::IncludeSorter::IncludeStyle>::getEnumMapping() {
                    {utils::IncludeSorter::IS_Google_ObjC, "google-objc"}};
   return ArrayRef(Mapping);
 }
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy

diff  --git a/clang-tools-extra/clang-tidy/utils/LexerUtils.cpp b/clang-tools-extra/clang-tidy/utils/LexerUtils.cpp
index 413ca683ee707..49718962f62f1 100644
--- a/clang-tools-extra/clang-tidy/utils/LexerUtils.cpp
+++ b/clang-tools-extra/clang-tidy/utils/LexerUtils.cpp
@@ -11,10 +11,7 @@
 #include "clang/Basic/SourceManager.h"
 #include <optional>
 
-namespace clang {
-namespace tidy {
-namespace utils {
-namespace lexer {
+namespace clang::tidy::utils::lexer {
 
 Token getPreviousToken(SourceLocation Location, const SourceManager &SM,
                        const LangOptions &LangOpts, bool SkipComments) {
@@ -215,7 +212,4 @@ SourceLocation getUnifiedEndLoc(const Stmt &S, const SourceManager &SM,
   return S.getEndLoc();
 }
 
-} // namespace lexer
-} // namespace utils
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::utils::lexer

diff  --git a/clang-tools-extra/clang-tidy/utils/NamespaceAliaser.cpp b/clang-tools-extra/clang-tidy/utils/NamespaceAliaser.cpp
index 93561232fe7a5..4703ce1269819 100644
--- a/clang-tools-extra/clang-tidy/utils/NamespaceAliaser.cpp
+++ b/clang-tools-extra/clang-tidy/utils/NamespaceAliaser.cpp
@@ -13,9 +13,7 @@
 #include "clang/ASTMatchers/ASTMatchers.h"
 #include "clang/Lex/Lexer.h"
 #include <optional>
-namespace clang {
-namespace tidy {
-namespace utils {
+namespace clang::tidy::utils {
 
 using namespace ast_matchers;
 
@@ -92,6 +90,4 @@ std::string NamespaceAliaser::getNamespaceName(ASTContext &Context,
   return Namespace.str();
 }
 
-} // namespace utils
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::utils

diff  --git a/clang-tools-extra/clang-tidy/utils/OptionsUtils.cpp b/clang-tools-extra/clang-tidy/utils/OptionsUtils.cpp
index b443aac7eeaf8..1866ea3f5b58a 100644
--- a/clang-tools-extra/clang-tidy/utils/OptionsUtils.cpp
+++ b/clang-tools-extra/clang-tidy/utils/OptionsUtils.cpp
@@ -9,10 +9,7 @@
 #include "OptionsUtils.h"
 #include "llvm/ADT/StringExtras.h"
 
-namespace clang {
-namespace tidy {
-namespace utils {
-namespace options {
+namespace clang::tidy::utils::options {
 
 static const char StringsDelimiter[] = ";";
 
@@ -63,7 +60,4 @@ std::string serializeStringList(ArrayRef<StringRef> Strings) {
   return llvm::join(Strings, StringsDelimiter);
 }
 
-} // namespace options
-} // namespace utils
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::utils::options

diff  --git a/clang-tools-extra/clang-tidy/utils/RenamerClangTidyCheck.cpp b/clang-tools-extra/clang-tidy/utils/RenamerClangTidyCheck.cpp
index e3c22c357ec7a..160910b000425 100644
--- a/clang-tools-extra/clang-tidy/utils/RenamerClangTidyCheck.cpp
+++ b/clang-tools-extra/clang-tidy/utils/RenamerClangTidyCheck.cpp
@@ -59,8 +59,7 @@ struct DenseMapInfo<clang::tidy::RenamerClangTidyCheck::NamingCheckId> {
 
 } // namespace llvm
 
-namespace clang {
-namespace tidy {
+namespace clang::tidy {
 
 namespace {
 
@@ -563,5 +562,4 @@ void RenamerClangTidyCheck::onEndOfTranslationUnit() {
   }
 }
 
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy

diff  --git a/clang-tools-extra/clang-tidy/utils/TransformerClangTidyCheck.cpp b/clang-tools-extra/clang-tidy/utils/TransformerClangTidyCheck.cpp
index f69be2f6dcbdf..dcdbcd36cba3c 100644
--- a/clang-tools-extra/clang-tidy/utils/TransformerClangTidyCheck.cpp
+++ b/clang-tools-extra/clang-tidy/utils/TransformerClangTidyCheck.cpp
@@ -12,9 +12,7 @@
 #include "llvm/ADT/STLExtras.h"
 #include <optional>
 
-namespace clang {
-namespace tidy {
-namespace utils {
+namespace clang::tidy::utils {
 using transformer::RewriteRuleWith;
 
 #ifndef NDEBUG
@@ -157,6 +155,4 @@ void TransformerClangTidyCheck::storeOptions(
   Options.store(Opts, "IncludeStyle", Inserter.getStyle());
 }
 
-} // namespace utils
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::utils

diff  --git a/clang-tools-extra/clang-tidy/utils/TypeTraits.cpp b/clang-tools-extra/clang-tidy/utils/TypeTraits.cpp
index 0dbbd5279368e..270b438c00c18 100644
--- a/clang-tools-extra/clang-tidy/utils/TypeTraits.cpp
+++ b/clang-tools-extra/clang-tidy/utils/TypeTraits.cpp
@@ -12,10 +12,7 @@
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include <optional>
 
-namespace clang {
-namespace tidy {
-namespace utils {
-namespace type_traits {
+namespace clang::tidy::utils::type_traits {
 
 namespace {
 
@@ -162,7 +159,4 @@ bool hasNonTrivialMoveAssignment(QualType Type) {
          Record->hasNonTrivialMoveAssignment();
 }
 
-} // namespace type_traits
-} // namespace utils
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::utils::type_traits

diff  --git a/clang-tools-extra/clang-tidy/utils/UsingInserter.cpp b/clang-tools-extra/clang-tidy/utils/UsingInserter.cpp
index 22bef9af47a87..d9e0f3fc0f61b 100644
--- a/clang-tools-extra/clang-tidy/utils/UsingInserter.cpp
+++ b/clang-tools-extra/clang-tidy/utils/UsingInserter.cpp
@@ -14,9 +14,7 @@
 #include "clang/Lex/Lexer.h"
 #include <optional>
 
-namespace clang {
-namespace tidy {
-namespace utils {
+namespace clang::tidy::utils {
 
 using namespace ast_matchers;
 
@@ -84,6 +82,4 @@ StringRef UsingInserter::getShortName(ASTContext &Context,
   return QualifiedName;
 }
 
-} // namespace utils
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::utils

diff  --git a/clang-tools-extra/clang-tidy/zircon/TemporaryObjectsCheck.cpp b/clang-tools-extra/clang-tidy/zircon/TemporaryObjectsCheck.cpp
index b75ab9dbb2fe3..240bb4ee2919a 100644
--- a/clang-tools-extra/clang-tidy/zircon/TemporaryObjectsCheck.cpp
+++ b/clang-tools-extra/clang-tidy/zircon/TemporaryObjectsCheck.cpp
@@ -16,9 +16,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace zircon {
+namespace clang::tidy::zircon {
 
 AST_MATCHER_P(CXXRecordDecl, matchesAnyName, ArrayRef<StringRef>, Names) {
   std::string QualifiedName = Node.getQualifiedNameAsString();
@@ -54,6 +52,4 @@ void TemporaryObjectsCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
   Options.store(Opts, "Names", utils::options::serializeStringList(Names));
 }
 
-} // namespace zircon
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::zircon

diff  --git a/clang-tools-extra/clang-tidy/zircon/ZirconTidyModule.cpp b/clang-tools-extra/clang-tidy/zircon/ZirconTidyModule.cpp
index 94bbd27a34d24..000680455d617 100644
--- a/clang-tools-extra/clang-tidy/zircon/ZirconTidyModule.cpp
+++ b/clang-tools-extra/clang-tidy/zircon/ZirconTidyModule.cpp
@@ -13,8 +13,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
+namespace clang::tidy {
 namespace zircon {
 
 /// This module is for Zircon-specific checks.
@@ -35,5 +34,4 @@ static ClangTidyModuleRegistry::Add<ZirconModule>
 // and thus register the ZirconModule.
 volatile int ZirconModuleAnchorSource = 0;
 
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy