r262881 - P0188R1: add support for standard [[fallthrough]] attribute. This is almost

Richard Smith via cfe-commits cfe-commits at lists.llvm.org
Tue Mar 8 10:49:10 PST 2016


On Tue, Mar 8, 2016 at 9:05 AM, Nico Weber <thakis at chromium.org> wrote:
> This causes clang to warn on
>
>   default: assert (false); HB_FALLTHROUGH;

What follows this? (A case label?) What warning is being produced?

> The fallthrough needs to be there for release builds, but now it must not be
> there for debug builds. I suppose this means projects now need an
> UNREACHED_CASE macro that expands to assert(false) in debug and to
> fallthrough in release (with clang; and to something else with other
> compilers)?
>
> On Mon, Mar 7, 2016 at 7:32 PM, Richard Smith via cfe-commits
> <cfe-commits at lists.llvm.org> wrote:
>>
>> Author: rsmith
>> Date: Mon Mar  7 18:32:55 2016
>> New Revision: 262881
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=262881&view=rev
>> Log:
>> P0188R1: add support for standard [[fallthrough]] attribute. This is
>> almost
>> exactly the same as clang's existing [[clang::fallthrough]] attribute,
>> which
>> has been updated to have the same semantics. The one significant
>> difference
>> is that [[fallthrough]] is ill-formed if it's not used immediately before
>> a
>> switch label (even when -Wimplicit-fallthrough is disabled). To support
>> that,
>> we now build a CFG of any function that uses a '[[fallthrough]];'
>> statement
>> to check.
>>
>> In passing, fix some bugs with our support for statement attributes -- in
>> particular, diagnose their use on declarations, rather than asserting.
>>
>> Modified:
>>     cfe/trunk/include/clang/AST/Attr.h
>>     cfe/trunk/include/clang/Basic/Attr.td
>>     cfe/trunk/include/clang/Basic/AttrDocs.td
>>     cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
>>     cfe/trunk/include/clang/Sema/AttributeList.h
>>     cfe/trunk/include/clang/Sema/ScopeInfo.h
>>     cfe/trunk/lib/Sema/AnalysisBasedWarnings.cpp
>>     cfe/trunk/lib/Sema/AttributeList.cpp
>>     cfe/trunk/lib/Sema/SemaDeclAttr.cpp
>>     cfe/trunk/lib/Sema/SemaStmtAttr.cpp
>>     cfe/trunk/test/Analysis/cxx11-crashes.cpp
>>     cfe/trunk/test/PCH/Inputs/cxx11-statement-attributes.h
>>     cfe/trunk/test/PCH/cxx11-statement-attributes.cpp
>>     cfe/trunk/test/Parser/cxx0x-attributes.cpp
>>     cfe/trunk/test/SemaCXX/for-range-examples.cpp
>>     cfe/trunk/test/SemaCXX/generalized-deprecated.cpp
>>     cfe/trunk/test/SemaCXX/nodiscard.cpp
>>     cfe/trunk/test/SemaCXX/switch-implicit-fallthrough-macro.cpp
>>     cfe/trunk/test/SemaCXX/switch-implicit-fallthrough-per-method.cpp
>>     cfe/trunk/test/SemaCXX/switch-implicit-fallthrough.cpp
>>     cfe/trunk/utils/TableGen/ClangAttrEmitter.cpp
>>     cfe/trunk/www/cxx_status.html
>>
>> Modified: cfe/trunk/include/clang/AST/Attr.h
>> URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/AST/Attr.h?rev=262881&r1=262880&r2=262881&view=diff
>>
>> ==============================================================================
>> --- cfe/trunk/include/clang/AST/Attr.h (original)
>> +++ cfe/trunk/include/clang/AST/Attr.h Mon Mar  7 18:32:55 2016
>> @@ -118,6 +118,19 @@ public:
>>    bool duplicatesAllowed() const { return DuplicatesAllowed; }
>>  };
>>
>> +class StmtAttr : public Attr {
>> +protected:
>> +  StmtAttr(attr::Kind AK, SourceRange R, unsigned SpellingListIndex,
>> +                  bool IsLateParsed, bool DuplicatesAllowed)
>> +      : Attr(AK, R, SpellingListIndex, IsLateParsed, DuplicatesAllowed)
>> {}
>> +
>> +public:
>> +  static bool classof(const Attr *A) {
>> +    return A->getKind() >= attr::FirstStmtAttr &&
>> +           A->getKind() <= attr::LastStmtAttr;
>> +  }
>> +};
>> +
>>  class InheritableAttr : public Attr {
>>  protected:
>>    InheritableAttr(attr::Kind AK, SourceRange R, unsigned
>> SpellingListIndex,
>>
>> Modified: cfe/trunk/include/clang/Basic/Attr.td
>> URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/Attr.td?rev=262881&r1=262880&r2=262881&view=diff
>>
>> ==============================================================================
>> --- cfe/trunk/include/clang/Basic/Attr.td (original)
>> +++ cfe/trunk/include/clang/Basic/Attr.td Mon Mar  7 18:32:55 2016
>> @@ -311,6 +311,9 @@ class TypeAttr : Attr {
>>    let ASTNode = 0;
>>  }
>>
>> +/// A stmt attribute is not processed on a declaration or a type.
>> +class StmtAttr : Attr;
>> +
>>  /// An inheritable attribute is inherited by later redeclarations.
>>  class InheritableAttr : Attr;
>>
>> @@ -738,8 +741,9 @@ def ExtVectorType : Attr {
>>    let Documentation = [Undocumented];
>>  }
>>
>> -def FallThrough : Attr {
>> -  let Spellings = [CXX11<"clang", "fallthrough">];
>> +def FallThrough : StmtAttr {
>> +  let Spellings = [CXX11<"", "fallthrough", 201503>,
>> +                   CXX11<"clang", "fallthrough">];
>>  //  let Subjects = [NullStmt];
>>    let Documentation = [FallthroughDocs];
>>  }
>>
>> Modified: cfe/trunk/include/clang/Basic/AttrDocs.td
>> URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/AttrDocs.td?rev=262881&r1=262880&r2=262881&view=diff
>>
>> ==============================================================================
>> --- cfe/trunk/include/clang/Basic/AttrDocs.td (original)
>> +++ cfe/trunk/include/clang/Basic/AttrDocs.td Mon Mar  7 18:32:55 2016
>> @@ -756,9 +756,10 @@ potentially-evaluated discarded-value ex
>>
>>  def FallthroughDocs : Documentation {
>>    let Category = DocCatStmt;
>> +  let Heading = "fallthrough, clang::fallthrough";
>>    let Content = [{
>> -The ``clang::fallthrough`` attribute is used along with the
>> -``-Wimplicit-fallthrough`` argument to annotate intentional fall-through
>> +The ``fallthrough`` (or ``clang::fallthrough``) attribute is used
>> +to annotate intentional fall-through
>>  between switch labels.  It can only be applied to a null statement placed
>> at a
>>  point of execution between any statement and the next switch label.  It
>> is
>>  common to mark these places with a specific comment, but this attribute
>> is
>> @@ -769,6 +770,10 @@ control-flow statements like ``break;``,
>>  where ``break;`` can, but only if there are no statements on the
>> execution path
>>  between it and the next switch label.
>>
>> +By default, Clang does not warn on unannotated fallthrough from one
>> ``switch``
>> +case to another. Diagnostics on fallthrough without a corresponding
>> annotation
>> +can be enabled with the ``-Wimplicit-fallthrough`` argument.
>> +
>>  Here is an example:
>>
>>  .. code-block:: c++
>>
>> Modified: cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
>> URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td?rev=262881&r1=262880&r2=262881&view=diff
>>
>> ==============================================================================
>> --- cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td (original)
>> +++ cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td Mon Mar  7
>> 18:32:55 2016
>> @@ -2358,8 +2358,10 @@ def warn_cxx11_gnu_attribute_on_type : W
>>  def warn_unhandled_ms_attribute_ignored : Warning<
>>    "__declspec attribute %0 is not supported">,
>>    InGroup<IgnoredAttributes>;
>> -def err_attribute_invalid_on_stmt : Error<
>> +def err_decl_attribute_invalid_on_stmt : Error<
>>    "%0 attribute cannot be applied to a statement">;
>> +def err_stmt_attribute_invalid_on_decl : Error<
>> +  "%0 attribute cannot be applied to a declaration">;
>>  def warn_declspec_attribute_ignored : Warning<
>>    "attribute %0 is ignored, place it after "
>>    "\"%select{class|struct|interface|union|enum}1\" to apply attribute to
>> "
>> @@ -6592,8 +6594,11 @@ def warn_unused_result : Warning<
>>  def warn_unused_volatile : Warning<
>>    "expression result unused; assign into a variable to force a volatile
>> load">,
>>    InGroup<DiagGroup<"unused-volatile-lvalue">>;
>> -def ext_nodiscard_attr_is_a_cxx1z_extension : ExtWarn<
>> -  "use of the 'nodiscard' attribute is a C++1z extension">,
>> InGroup<CXX1z>;
>> +
>> +def ext_cxx14_attr : Extension<
>> +  "use of the %0 attribute is a C++14 extension">, InGroup<CXX14>;
>> +def ext_cxx1z_attr : Extension<
>> +  "use of the %0 attribute is a C++1z extension">, InGroup<CXX1z>;
>>
>>  def warn_unused_comparison : Warning<
>>    "%select{%select{|in}1equality|relational}0 comparison result unused">,
>> @@ -7306,13 +7311,12 @@ def note_insert_fallthrough_fixit : Note
>>  def note_insert_break_fixit : Note<
>>    "insert 'break;' to avoid fall-through">;
>>  def err_fallthrough_attr_wrong_target : Error<
>> -  "clang::fallthrough attribute is only allowed on empty statements">;
>> +  "%0 attribute is only allowed on empty statements">;
>>  def note_fallthrough_insert_semi_fixit : Note<"did you forget ';'?">;
>>  def err_fallthrough_attr_outside_switch : Error<
>>    "fallthrough annotation is outside switch statement">;
>> -def warn_fallthrough_attr_invalid_placement : Warning<
>> -  "fallthrough annotation does not directly precede switch label">,
>> -  InGroup<ImplicitFallthrough>;
>> +def err_fallthrough_attr_invalid_placement : Error<
>> +  "fallthrough annotation does not directly precede switch label">;
>>  def warn_fallthrough_attr_unreachable : Warning<
>>    "fallthrough annotation in unreachable code">,
>>    InGroup<ImplicitFallthrough>;
>> @@ -7678,9 +7682,6 @@ def err_asm_naked_this_ref : Error<
>>  def err_asm_naked_parm_ref : Error<
>>    "parameter references not allowed in naked functions">;
>>
>> -def ext_deprecated_attr_is_a_cxx14_extension : ExtWarn<
>> -  "use of the 'deprecated' attribute is a C++14 extension">,
>> InGroup<CXX14>;
>> -
>>  // OpenCL warnings and errors.
>>  def err_invalid_astype_of_different_size : Error<
>>    "invalid reinterpretation: sizes of %0 and %1 must match">;
>>
>> Modified: cfe/trunk/include/clang/Sema/AttributeList.h
>> URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Sema/AttributeList.h?rev=262881&r1=262880&r2=262881&view=diff
>>
>> ==============================================================================
>> --- cfe/trunk/include/clang/Sema/AttributeList.h (original)
>> +++ cfe/trunk/include/clang/Sema/AttributeList.h Mon Mar  7 18:32:55 2016
>> @@ -491,6 +491,7 @@ public:
>>
>>    bool isTargetSpecificAttr() const;
>>    bool isTypeAttr() const;
>> +  bool isStmtAttr() const;
>>
>>    bool hasCustomParsing() const;
>>    unsigned getMinArgs() const;
>>
>> Modified: cfe/trunk/include/clang/Sema/ScopeInfo.h
>> URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Sema/ScopeInfo.h?rev=262881&r1=262880&r2=262881&view=diff
>>
>> ==============================================================================
>> --- cfe/trunk/include/clang/Sema/ScopeInfo.h (original)
>> +++ cfe/trunk/include/clang/Sema/ScopeInfo.h Mon Mar  7 18:32:55 2016
>> @@ -107,6 +107,9 @@ public:
>>    /// \brief True if current scope is for OpenMP declare reduction
>> combiner.
>>    bool HasOMPDeclareReductionCombiner;
>>
>> +  /// \brief Whether there is a fallthrough statement in this function.
>> +  bool HasFallthroughStmt : 1;
>> +
>>    /// A flag that is set when parsing a method that must call super's
>>    /// implementation, such as \c -dealloc, \c -finalize, or any method
>> marked
>>    /// with \c __attribute__((objc_requires_super)).
>> @@ -348,6 +351,10 @@ public:
>>      HasOMPDeclareReductionCombiner = true;
>>    }
>>
>> +  void setHasFallthroughStmt() {
>> +    HasFallthroughStmt = true;
>> +  }
>> +
>>    void setHasCXXTry(SourceLocation TryLoc) {
>>      setHasBranchProtectedScope();
>>      FirstCXXTryLoc = TryLoc;
>> @@ -371,6 +378,7 @@ public:
>>        HasIndirectGoto(false),
>>        HasDroppedStmt(false),
>>        HasOMPDeclareReductionCombiner(false),
>> +      HasFallthroughStmt(false),
>>        ObjCShouldCallSuper(false),
>>        ObjCIsDesignatedInit(false),
>>        ObjCWarnForNoDesignatedInitChain(false),
>>
>> Modified: cfe/trunk/lib/Sema/AnalysisBasedWarnings.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/AnalysisBasedWarnings.cpp?rev=262881&r1=262880&r2=262881&view=diff
>>
>> ==============================================================================
>> --- cfe/trunk/lib/Sema/AnalysisBasedWarnings.cpp (original)
>> +++ cfe/trunk/lib/Sema/AnalysisBasedWarnings.cpp Mon Mar  7 18:32:55 2016
>> @@ -1071,6 +1071,34 @@ namespace {
>>    };
>>  } // anonymous namespace
>>
>> +static StringRef getFallthroughAttrSpelling(Preprocessor &PP,
>> +                                            SourceLocation Loc) {
>> +  TokenValue FallthroughTokens[] = {
>> +    tok::l_square, tok::l_square,
>> +    PP.getIdentifierInfo("fallthrough"),
>> +    tok::r_square, tok::r_square
>> +  };
>> +
>> +  TokenValue ClangFallthroughTokens[] = {
>> +    tok::l_square, tok::l_square, PP.getIdentifierInfo("clang"),
>> +    tok::coloncolon, PP.getIdentifierInfo("fallthrough"),
>> +    tok::r_square, tok::r_square
>> +  };
>> +
>> +  bool PreferClangAttr = !PP.getLangOpts().CPlusPlus1z;
>> +
>> +  StringRef MacroName;
>> +  if (PreferClangAttr)
>> +    MacroName = PP.getLastMacroWithSpelling(Loc, ClangFallthroughTokens);
>> +  if (MacroName.empty())
>> +    MacroName = PP.getLastMacroWithSpelling(Loc, FallthroughTokens);
>> +  if (MacroName.empty() && !PreferClangAttr)
>> +    MacroName = PP.getLastMacroWithSpelling(Loc, ClangFallthroughTokens);
>> +  if (MacroName.empty())
>> +    MacroName = PreferClangAttr ? "[[clang::fallthrough]]" :
>> "[[fallthrough]]";
>> +  return MacroName;
>> +}
>> +
>>  static void DiagnoseSwitchLabelsFallthrough(Sema &S, AnalysisDeclContext
>> &AC,
>>                                              bool PerFunction) {
>>    // Only perform this analysis when using C++11.  There is no good
>> workflow
>> @@ -1129,15 +1157,7 @@ static void DiagnoseSwitchLabelsFallthro
>>          }
>>          if (!(B->empty() && Term && isa<BreakStmt>(Term))) {
>>            Preprocessor &PP = S.getPreprocessor();
>> -          TokenValue Tokens[] = {
>> -            tok::l_square, tok::l_square, PP.getIdentifierInfo("clang"),
>> -            tok::coloncolon, PP.getIdentifierInfo("fallthrough"),
>> -            tok::r_square, tok::r_square
>> -          };
>> -          StringRef AnnotationSpelling = "[[clang::fallthrough]]";
>> -          StringRef MacroName = PP.getLastMacroWithSpelling(L, Tokens);
>> -          if (!MacroName.empty())
>> -            AnnotationSpelling = MacroName;
>> +          StringRef AnnotationSpelling = getFallthroughAttrSpelling(PP,
>> L);
>>            SmallString<64> TextToInsert(AnnotationSpelling);
>>            TextToInsert += "; ";
>>            S.Diag(L, diag::note_insert_fallthrough_fixit) <<
>> @@ -1151,7 +1171,7 @@ static void DiagnoseSwitchLabelsFallthro
>>    }
>>
>>    for (const auto *F : FM.getFallthroughStmts())
>> -    S.Diag(F->getLocStart(),
>> diag::warn_fallthrough_attr_invalid_placement);
>> +    S.Diag(F->getLocStart(),
>> diag::err_fallthrough_attr_invalid_placement);
>>  }
>>
>>  static bool isInLoop(const ASTContext &Ctx, const ParentMap &PM,
>> @@ -2038,7 +2058,8 @@ AnalysisBasedWarnings::IssueWarnings(sem
>>        !Diags.isIgnored(diag::warn_unannotated_fallthrough,
>> D->getLocStart());
>>    bool FallThroughDiagPerFunction = !Diags.isIgnored(
>>        diag::warn_unannotated_fallthrough_per_function, D->getLocStart());
>> -  if (FallThroughDiagFull || FallThroughDiagPerFunction) {
>> +  if (FallThroughDiagFull || FallThroughDiagPerFunction ||
>> +      fscope->HasFallthroughStmt) {
>>      DiagnoseSwitchLabelsFallthrough(S, AC, !FallThroughDiagFull);
>>    }
>>
>>
>> Modified: cfe/trunk/lib/Sema/AttributeList.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/AttributeList.cpp?rev=262881&r1=262880&r2=262881&view=diff
>>
>> ==============================================================================
>> --- cfe/trunk/lib/Sema/AttributeList.cpp (original)
>> +++ cfe/trunk/lib/Sema/AttributeList.cpp Mon Mar  7 18:32:55 2016
>> @@ -159,6 +159,7 @@ struct ParsedAttrInfo {
>>    unsigned HasCustomParsing : 1;
>>    unsigned IsTargetSpecific : 1;
>>    unsigned IsType : 1;
>> +  unsigned IsStmt : 1;
>>    unsigned IsKnownToGCC : 1;
>>
>>    bool (*DiagAppertainsToDecl)(Sema &S, const AttributeList &Attr,
>> @@ -204,6 +205,10 @@ bool AttributeList::isTypeAttr() const {
>>    return getInfo(*this).IsType;
>>  }
>>
>> +bool AttributeList::isStmtAttr() const {
>> +  return getInfo(*this).IsStmt;
>> +}
>> +
>>  bool AttributeList::existsInTarget(const TargetInfo &Target) const {
>>    return getInfo(*this).ExistsInTarget(Target);
>>  }
>>
>> Modified: cfe/trunk/lib/Sema/SemaDeclAttr.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaDeclAttr.cpp?rev=262881&r1=262880&r2=262881&view=diff
>>
>> ==============================================================================
>> --- cfe/trunk/lib/Sema/SemaDeclAttr.cpp (original)
>> +++ cfe/trunk/lib/Sema/SemaDeclAttr.cpp Mon Mar  7 18:32:55 2016
>> @@ -2467,7 +2467,7 @@ static void handleWarnUnusedResult(Sema
>>    // about using it as an extension.
>>    if (!S.getLangOpts().CPlusPlus1z && Attr.isCXX11Attribute() &&
>>        !Attr.getScopeName())
>> -    S.Diag(Attr.getLoc(), diag::ext_nodiscard_attr_is_a_cxx1z_extension);
>> +    S.Diag(Attr.getLoc(), diag::ext_cxx1z_attr) << Attr.getName();
>>
>>    D->addAttr(::new (S.Context)
>>               WarnUnusedResultAttr(Attr.getRange(), S.Context,
>> @@ -5072,7 +5072,7 @@ static void handleDeprecatedAttr(Sema &S
>>    if (!S.getLangOpts().CPlusPlus14)
>>      if (Attr.isCXX11Attribute() &&
>>          !(Attr.hasScope() && Attr.getScopeName()->isStr("gnu")))
>> -      S.Diag(Attr.getLoc(),
>> diag::ext_deprecated_attr_is_a_cxx14_extension);
>> +      S.Diag(Attr.getLoc(), diag::ext_cxx14_attr) << Attr.getName();
>>
>>    handleAttrWithMessage<DeprecatedAttr>(S, D, Attr);
>>  }
>> @@ -5234,8 +5234,13 @@ static void ProcessDeclAttribute(Sema &S
>>
>>    switch (Attr.getKind()) {
>>    default:
>> -    // Type attributes are handled elsewhere; silently move on.
>> -    assert(Attr.isTypeAttr() && "Non-type attribute not handled");
>> +    if (!Attr.isStmtAttr()) {
>> +      // Type attributes are handled elsewhere; silently move on.
>> +      assert(Attr.isTypeAttr() && "Non-type attribute not handled");
>> +      break;
>> +    }
>> +    S.Diag(Attr.getLoc(), diag::err_stmt_attribute_invalid_on_decl)
>> +        << Attr.getName() << D->getLocation();
>>      break;
>>    case AttributeList::AT_Interrupt:
>>      handleInterruptAttr(S, D, Attr);
>>
>> Modified: cfe/trunk/lib/Sema/SemaStmtAttr.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaStmtAttr.cpp?rev=262881&r1=262880&r2=262881&view=diff
>>
>> ==============================================================================
>> --- cfe/trunk/lib/Sema/SemaStmtAttr.cpp (original)
>> +++ cfe/trunk/lib/Sema/SemaStmtAttr.cpp Mon Mar  7 18:32:55 2016
>> @@ -25,9 +25,11 @@ using namespace sema;
>>
>>  static Attr *handleFallThroughAttr(Sema &S, Stmt *St, const AttributeList
>> &A,
>>                                     SourceRange Range) {
>> +  FallThroughAttr Attr(A.getRange(), S.Context,
>> +                       A.getAttributeSpellingListIndex());
>>    if (!isa<NullStmt>(St)) {
>>      S.Diag(A.getRange().getBegin(),
>> diag::err_fallthrough_attr_wrong_target)
>> -        << St->getLocStart();
>> +        << Attr.getSpelling() << St->getLocStart();
>>      if (isa<SwitchCase>(St)) {
>>        SourceLocation L = S.getLocForEndOfToken(Range.getEnd());
>>        S.Diag(L, diag::note_fallthrough_insert_semi_fixit)
>> @@ -35,12 +37,20 @@ static Attr *handleFallThroughAttr(Sema
>>      }
>>      return nullptr;
>>    }
>> -  if (S.getCurFunction()->SwitchStack.empty()) {
>> +  auto *FnScope = S.getCurFunction();
>> +  if (FnScope->SwitchStack.empty()) {
>>      S.Diag(A.getRange().getBegin(),
>> diag::err_fallthrough_attr_outside_switch);
>>      return nullptr;
>>    }
>> -  return ::new (S.Context) FallThroughAttr(A.getRange(), S.Context,
>> -
>> A.getAttributeSpellingListIndex());
>> +
>> +  // If this is spelled as the standard C++1z attribute, but not in
>> C++1z, warn
>> +  // about using it as an extension.
>> +  if (!S.getLangOpts().CPlusPlus1z && A.isCXX11Attribute() &&
>> +      !A.getScopeName())
>> +    S.Diag(A.getLoc(), diag::ext_cxx1z_attr) << A.getName();
>> +
>> +  FnScope->setHasFallthroughStmt();
>> +  return ::new (S.Context) auto(Attr);
>>  }
>>
>>  static Attr *handleLoopHintAttr(Sema &S, Stmt *St, const AttributeList
>> &A,
>> @@ -266,7 +276,7 @@ static Attr *ProcessStmtAttribute(Sema &
>>    default:
>>      // if we're here, then we parsed a known attribute, but didn't
>> recognize
>>      // it as a statement attribute => it is declaration attribute
>> -    S.Diag(A.getRange().getBegin(), diag::err_attribute_invalid_on_stmt)
>> +    S.Diag(A.getRange().getBegin(),
>> diag::err_decl_attribute_invalid_on_stmt)
>>          << A.getName() << St->getLocStart();
>>      return nullptr;
>>    }
>>
>> Modified: cfe/trunk/test/Analysis/cxx11-crashes.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Analysis/cxx11-crashes.cpp?rev=262881&r1=262880&r2=262881&view=diff
>>
>> ==============================================================================
>> --- cfe/trunk/test/Analysis/cxx11-crashes.cpp (original)
>> +++ cfe/trunk/test/Analysis/cxx11-crashes.cpp Mon Mar  7 18:32:55 2016
>> @@ -1,5 +1,4 @@
>>  // RUN: %clang_cc1 -analyze -analyzer-checker=core -std=c++11 -verify %s
>> -// expected-no-diagnostics
>>
>>  // radar://11485149, PR12871
>>  class PlotPoint {
>> @@ -91,6 +90,6 @@ void test() {
>>  void fallthrough() {
>>    switch (1) {
>>      case 1:
>> -      [[clang::fallthrough]];
>> +      [[clang::fallthrough]]; // expected-error {{does not directly
>> precede}}
>>    }
>>  }
>>
>> Modified: cfe/trunk/test/PCH/Inputs/cxx11-statement-attributes.h
>> URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/PCH/Inputs/cxx11-statement-attributes.h?rev=262881&r1=262880&r2=262881&view=diff
>>
>> ==============================================================================
>> --- cfe/trunk/test/PCH/Inputs/cxx11-statement-attributes.h (original)
>> +++ cfe/trunk/test/PCH/Inputs/cxx11-statement-attributes.h Mon Mar  7
>> 18:32:55 2016
>> @@ -7,7 +7,8 @@ int f(int n) {
>>        [[clang::fallthrough]];  // This shouldn't generate a warning.
>>      case 1:
>>        n += 20;
>> -      [[clang::fallthrough]];  // This should generate a warning:
>> "fallthrough annotation does not directly precede switch label".
>> +    case 2:  // This should generate a warning: "unannotated fallthrough"
>> +      n += 35;
>>        break;
>>    }
>>    return n;
>>
>> Modified: cfe/trunk/test/PCH/cxx11-statement-attributes.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/PCH/cxx11-statement-attributes.cpp?rev=262881&r1=262880&r2=262881&view=diff
>>
>> ==============================================================================
>> --- cfe/trunk/test/PCH/cxx11-statement-attributes.cpp (original)
>> +++ cfe/trunk/test/PCH/cxx11-statement-attributes.cpp Mon Mar  7 18:32:55
>> 2016
>> @@ -1,10 +1,15 @@
>>  // Sanity check.
>>  // RUN: %clang_cc1 -include %S/Inputs/cxx11-statement-attributes.h
>> -std=c++11 -Wimplicit-fallthrough -fsyntax-only %s -o - -verify
>> +// RUN: %clang_cc1 -include %S/Inputs/cxx11-statement-attributes.h
>> -std=c++1z -Wimplicit-fallthrough -fsyntax-only %s -o - -verify
>>  // Run the same tests, this time with the attributes loaded from the PCH
>> file.
>>  // RUN: %clang_cc1 -x c++-header -emit-pch -std=c++11 -o %t
>> %S/Inputs/cxx11-statement-attributes.h
>>  // RUN: %clang_cc1 -include-pch %t -std=c++11 -Wimplicit-fallthrough
>> -fsyntax-only %s -o - -verify
>> +// RUN: %clang_cc1 -x c++-header -emit-pch -std=c++1z -o %t
>> %S/Inputs/cxx11-statement-attributes.h
>> +// RUN: %clang_cc1 -include-pch %t -std=c++1z -Wimplicit-fallthrough
>> -fsyntax-only %s -o - -verify
>>
>> -// expected-warning at Inputs/cxx11-statement-attributes.h:10 {{fallthrough
>> annotation does not directly precede switch label}}
>> +// expected-warning at Inputs/cxx11-statement-attributes.h:10 {{unannotated
>> fall-through}}
>> +// expected-note-re at Inputs/cxx11-statement-attributes.h:10 {{insert
>> '[[{{(clang::)?}}fallthrough]];'}}
>> +// expected-note at Inputs/cxx11-statement-attributes.h:10 {{insert
>> 'break;'}}
>>
>>  void g(int n) {
>>    f<1>(n);  // expected-note {{in instantiation of function template
>> specialization 'f<1>' requested here}}
>>
>> Modified: cfe/trunk/test/Parser/cxx0x-attributes.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Parser/cxx0x-attributes.cpp?rev=262881&r1=262880&r2=262881&view=diff
>>
>> ==============================================================================
>> --- cfe/trunk/test/Parser/cxx0x-attributes.cpp (original)
>> +++ cfe/trunk/test/Parser/cxx0x-attributes.cpp Mon Mar  7 18:32:55 2016
>> @@ -1,4 +1,4 @@
>> -// RUN: %clang_cc1 -fcxx-exceptions -fexceptions -fsyntax-only -verify
>> -std=c++11 -Wc++14-compat %s
>> +// RUN: %clang_cc1 -fcxx-exceptions -fexceptions -fsyntax-only -verify
>> -std=c++11 -Wc++14-compat -Wc++14-extensions -Wc++1z-extensions %s
>>
>>  // Need std::initializer_list
>>  namespace std {
>> @@ -347,6 +347,18 @@ deprecated
>>  ]] void bad();
>>  }
>>
>> +int fallthru(int n) {
>> +  switch (n) {
>> +  case 0:
>> +    n += 5;
>> +    [[fallthrough]]; // expected-warning {{use of the 'fallthrough'
>> attribute is a C++1z extension}}
>> +  case 1:
>> +    n *= 2;
>> +    break;
>> +  }
>> +  return n;
>> +}
>> +
>>  #define attr_name bitand
>>  #define attr_name_2(x) x
>>  #define attr_name_3(x, y) x##y
>>
>> Modified: cfe/trunk/test/SemaCXX/for-range-examples.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/for-range-examples.cpp?rev=262881&r1=262880&r2=262881&view=diff
>>
>> ==============================================================================
>> --- cfe/trunk/test/SemaCXX/for-range-examples.cpp (original)
>> +++ cfe/trunk/test/SemaCXX/for-range-examples.cpp Mon Mar  7 18:32:55 2016
>> @@ -226,7 +226,7 @@ namespace test7 {
>>      // we check the alignment attribute before we perform the auto
>>      // deduction.
>>      for (d alignas(1) : arr) {} // expected-error {{requires type for
>> loop variable}}
>> -    for (e [[deprecated]] : arr) { e = 0; } // expected-warning{{use of
>> the 'deprecated' attribute is a C++14 extension}} expected-warning
>> {{deprecated}} expected-note {{here}} expected-error {{requires type for
>> loop variable}}
>> +    for (e [[deprecated]] : arr) { e = 0; } // expected-warning
>> {{deprecated}} expected-note {{here}} expected-error {{requires type for
>> loop variable}}
>>    }
>>  }
>>
>>
>> Modified: cfe/trunk/test/SemaCXX/generalized-deprecated.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/generalized-deprecated.cpp?rev=262881&r1=262880&r2=262881&view=diff
>>
>> ==============================================================================
>> --- cfe/trunk/test/SemaCXX/generalized-deprecated.cpp (original)
>> +++ cfe/trunk/test/SemaCXX/generalized-deprecated.cpp Mon Mar  7 18:32:55
>> 2016
>> @@ -1,4 +1,4 @@
>> -// RUN: %clang_cc1 -std=c++11 -verify -fsyntax-only -fms-extensions
>> -Wno-deprecated %s
>> +// RUN: %clang_cc1 -std=c++11 -verify -fsyntax-only -fms-extensions
>> -Wno-deprecated -Wc++14-extensions %s
>>
>>  // NOTE: use -Wno-deprecated to avoid cluttering the output with
>> deprecated
>>  // warnings
>>
>> Modified: cfe/trunk/test/SemaCXX/nodiscard.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/nodiscard.cpp?rev=262881&r1=262880&r2=262881&view=diff
>>
>> ==============================================================================
>> --- cfe/trunk/test/SemaCXX/nodiscard.cpp (original)
>> +++ cfe/trunk/test/SemaCXX/nodiscard.cpp Mon Mar  7 18:32:55 2016
>> @@ -1,5 +1,5 @@
>> -// RUN: %clang_cc1 -fsyntax-only -std=c++1z -verify %s
>> -// RUN: %clang_cc1 -fsyntax-only -std=c++11 -verify -DEXT %s
>> +// RUN: %clang_cc1 -fsyntax-only -std=c++1z -verify -Wc++1z-extensions %s
>> +// RUN: %clang_cc1 -fsyntax-only -std=c++11 -verify -DEXT
>> -Wc++1z-extensions %s
>>
>>  #if !defined(EXT)
>>  static_assert(__has_cpp_attribute(nodiscard) == 201603);
>>
>> Modified: cfe/trunk/test/SemaCXX/switch-implicit-fallthrough-macro.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/switch-implicit-fallthrough-macro.cpp?rev=262881&r1=262880&r2=262881&view=diff
>>
>> ==============================================================================
>> --- cfe/trunk/test/SemaCXX/switch-implicit-fallthrough-macro.cpp
>> (original)
>> +++ cfe/trunk/test/SemaCXX/switch-implicit-fallthrough-macro.cpp Mon Mar
>> 7 18:32:55 2016
>> @@ -1,4 +1,8 @@
>> -// RUN: %clang_cc1 -fsyntax-only -verify -std=c++11
>> -Wimplicit-fallthrough -DCOMMAND_LINE_FALLTHROUGH=[[clang::fallthrough]] %s
>> +// RUN: %clang_cc1 -fsyntax-only -verify -std=c++11
>> -Wimplicit-fallthrough -DCLANG_PREFIX
>> -DCOMMAND_LINE_FALLTHROUGH=[[clang::fallthrough]] -DUNCHOSEN=[[fallthrough]]
>> %s
>> +// RUN: %clang_cc1 -fsyntax-only -verify -std=c++11
>> -Wimplicit-fallthrough -DCOMMAND_LINE_FALLTHROUGH=[[fallthrough]] %s
>> +// RUN: %clang_cc1 -fsyntax-only -verify -std=c++1z
>> -Wimplicit-fallthrough -DCLANG_PREFIX
>> -DCOMMAND_LINE_FALLTHROUGH=[[clang::fallthrough]] %s
>> +// RUN: %clang_cc1 -fsyntax-only -verify -std=c++1z
>> -Wimplicit-fallthrough -DCOMMAND_LINE_FALLTHROUGH=[[clang::fallthrough]] %s
>> +// RUN: %clang_cc1 -fsyntax-only -verify -std=c++1z
>> -Wimplicit-fallthrough -DCOMMAND_LINE_FALLTHROUGH=[[fallthrough]]
>> -DUNCHOSEN=[[clang::fallthrough]] %s
>>
>>  int fallthrough_compatibility_macro_from_command_line(int n) {
>>    switch (n) {
>> @@ -10,15 +14,12 @@ int fallthrough_compatibility_macro_from
>>    return n;
>>  }
>>
>> -#ifdef __clang__
>> -#if __has_feature(cxx_attributes) &&
>> __has_warning("-Wimplicit-fallthrough")
>> +#ifdef CLANG_PREFIX
>>  #define COMPATIBILITY_FALLTHROUGH   [ [ /* test */  clang /* test */ \
>>      ::  fallthrough  ]  ]    // testing whitespace and comments in macro
>> definition
>> -#endif
>> -#endif
>> -
>> -#ifndef COMPATIBILITY_FALLTHROUGH
>> -#define COMPATIBILITY_FALLTHROUGH do { } while (0)
>> +#else
>> +#define COMPATIBILITY_FALLTHROUGH   [ [ /* test */  /* test */ \
>> +    fallthrough  ]  ]    // testing whitespace and comments in macro
>> definition
>>  #endif
>>
>>  int fallthrough_compatibility_macro_from_source(int n) {
>> @@ -32,7 +33,11 @@ int fallthrough_compatibility_macro_from
>>  }
>>
>>  // Deeper macro substitution
>> +#ifdef CLANG_PREFIX
>>  #define M1 [[clang::fallthrough]]
>> +#else
>> +#define M1 [[fallthrough]]
>> +#endif
>>  #ifdef __clang__
>>  #define M2 M1
>>  #else
>> @@ -59,12 +64,17 @@ int fallthrough_compatibility_macro_in_m
>>  #undef M2
>>  #undef COMPATIBILITY_FALLTHROUGH
>>  #undef COMMAND_LINE_FALLTHROUGH
>> +#undef UNCHOSEN
>>
>>  int fallthrough_compatibility_macro_undefined(int n) {
>>    switch (n) {
>>      case 0:
>>        n = n * 20;
>> +#if __cplusplus <= 201402L
>>      case 1: // expected-warning{{unannotated fall-through between switch
>> labels}} expected-note{{insert '[[clang::fallthrough]];' to silence this
>> warning}} expected-note{{insert 'break;' to avoid fall-through}}
>> +#else
>> +    case 1: // expected-warning{{unannotated fall-through between switch
>> labels}} expected-note{{insert '[[fallthrough]];' to silence this warning}}
>> expected-note{{insert 'break;' to avoid fall-through}}
>> +#endif
>>        ;
>>    }
>>  #define TOO_LATE [[clang::fallthrough]]
>> @@ -83,7 +93,11 @@ int fallthrough_compatibility_macro_hist
>>      case 0:
>>        n = n * 20;
>>  #undef MACRO_WITH_HISTORY
>> +#if __cplusplus <= 201402L
>>      case 1: // expected-warning{{unannotated fall-through between switch
>> labels}} expected-note{{insert '[[clang::fallthrough]];' to silence this
>> warning}} expected-note{{insert 'break;' to avoid fall-through}}
>> +#else
>> +    case 1: // expected-warning{{unannotated fall-through between switch
>> labels}} expected-note{{insert '[[fallthrough]];' to silence this warning}}
>> expected-note{{insert 'break;' to avoid fall-through}}
>> +#endif
>>        ;
>>  #define MACRO_WITH_HISTORY [[clang::fallthrough]]
>>    }
>>
>> Modified:
>> cfe/trunk/test/SemaCXX/switch-implicit-fallthrough-per-method.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/switch-implicit-fallthrough-per-method.cpp?rev=262881&r1=262880&r2=262881&view=diff
>>
>> ==============================================================================
>> --- cfe/trunk/test/SemaCXX/switch-implicit-fallthrough-per-method.cpp
>> (original)
>> +++ cfe/trunk/test/SemaCXX/switch-implicit-fallthrough-per-method.cpp Mon
>> Mar  7 18:32:55 2016
>> @@ -41,9 +41,8 @@ int fallthrough2(int n) {
>>  void unscoped(int n) {
>>    switch (n % 2) {
>>      case 0:
>> -      // FIXME: This should be typo-corrected, probably.
>> -      [[fallthrough]]; // expected-warning{{unknown attribute
>> 'fallthrough' ignored}}
>> -    case 2: // expected-warning{{unannotated fall-through}}
>> expected-note{{clang::fallthrough}} expected-note{{break;}}
>> +      [[fallthrough]];
>> +    case 2:
>>        [[clang::fallthrough]];
>>      case 1:
>>        break;
>>
>> Modified: cfe/trunk/test/SemaCXX/switch-implicit-fallthrough.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/switch-implicit-fallthrough.cpp?rev=262881&r1=262880&r2=262881&view=diff
>>
>> ==============================================================================
>> --- cfe/trunk/test/SemaCXX/switch-implicit-fallthrough.cpp (original)
>> +++ cfe/trunk/test/SemaCXX/switch-implicit-fallthrough.cpp Mon Mar  7
>> 18:32:55 2016
>> @@ -179,18 +179,15 @@ void fallthrough_cfgblock_with_null_succ
>>
>>  int fallthrough_position(int n) {
>>    switch (n) {
>> -      [[clang::fallthrough]];  // expected-warning{{fallthrough
>> annotation does not directly precede switch label}}
>>        n += 300;
>>        [[clang::fallthrough]];  // expected-warning{{fallthrough
>> annotation in unreachable code}}
>>      case 221:
>> -      [[clang::fallthrough]];  // expected-warning{{fallthrough
>> annotation does not directly precede switch label}}
>>        return 1;
>>        [[clang::fallthrough]];  // expected-warning{{fallthrough
>> annotation in unreachable code}}
>>      case 222:
>> -      [[clang::fallthrough]];  // expected-warning{{fallthrough
>> annotation does not directly precede switch label}}
>>        n += 400;
>>      case 223:          // expected-warning{{unannotated fall-through
>> between switch labels}} expected-note{{insert '[[clang::fallthrough]];' to
>> silence this warning}} expected-note{{insert 'break;' to avoid
>> fall-through}}
>> -      [[clang::fallthrough]]; // expected-warning{{fallthrough annotation
>> does not directly precede switch label}}
>> +      ;
>>    }
>>
>>    long p = static_cast<long>(n) * n;
>> @@ -282,6 +279,23 @@ namespace PR18983 {
>>    }
>>  }
>>
>> +int fallthrough_placement_error(int n) {
>> +  switch (n) {
>> +      [[clang::fallthrough]]; // expected-warning{{fallthrough annotation
>> in unreachable code}}
>> +      n += 300;
>> +    case 221:
>> +      [[clang::fallthrough]]; // expected-error{{fallthrough annotation
>> does not directly precede switch label}}
>> +      return 1;
>> +    case 222:
>> +      [[clang::fallthrough]]; // expected-error{{fallthrough annotation
>> does not directly precede switch label}}
>> +      n += 400;
>> +      [[clang::fallthrough]];
>> +    case 223:
>> +      [[clang::fallthrough]]; // expected-error{{fallthrough annotation
>> does not directly precede switch label}}
>> +  }
>> +  return n;
>> +}
>> +
>>  int fallthrough_targets(int n) {
>>    [[clang::fallthrough]]; // expected-error{{fallthrough annotation is
>> outside switch statement}}
>>
>>
>> Modified: cfe/trunk/utils/TableGen/ClangAttrEmitter.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/utils/TableGen/ClangAttrEmitter.cpp?rev=262881&r1=262880&r2=262881&view=diff
>>
>> ==============================================================================
>> --- cfe/trunk/utils/TableGen/ClangAttrEmitter.cpp (original)
>> +++ cfe/trunk/utils/TableGen/ClangAttrEmitter.cpp Mon Mar  7 18:32:55 2016
>> @@ -1761,6 +1761,7 @@ namespace {
>>
>>  static const AttrClassDescriptor AttrClassDescriptors[] = {
>>    { "ATTR", "Attr" },
>> +  { "STMT_ATTR", "StmtAttr" },
>>    { "INHERITABLE_ATTR", "InheritableAttr" },
>>    { "INHERITABLE_PARAM_ATTR", "InheritableParamAttr" },
>>    { "PARAMETER_ABI_ATTR", "ParameterABIAttr" }
>> @@ -2806,6 +2807,7 @@ void EmitClangAttrParsedAttrImpl(RecordK
>>      SS << ", " << I->second->getValueAsBit("HasCustomParsing");
>>      SS << ", " << I->second->isSubClassOf("TargetSpecificAttr");
>>      SS << ", " << I->second->isSubClassOf("TypeAttr");
>> +    SS << ", " << I->second->isSubClassOf("StmtAttr");
>>      SS << ", " << IsKnownToGCC(*I->second);
>>      SS << ", " << GenerateAppertainsTo(*I->second, OS);
>>      SS << ", " << GenerateLangOptRequirements(*I->second, OS);
>>
>> Modified: cfe/trunk/www/cxx_status.html
>> URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/www/cxx_status.html?rev=262881&r1=262880&r2=262881&view=diff
>>
>> ==============================================================================
>> --- cfe/trunk/www/cxx_status.html (original)
>> +++ cfe/trunk/www/cxx_status.html Mon Mar  7 18:32:55 2016
>> @@ -629,7 +629,7 @@ as the draft C++1z standard evolves.</p>
>>      <tr>
>>        <td><tt>[[fallthrough]]</tt> attribute</td>
>>        <td><a href="http://wg21.link/p0188r1">P0188R1</a></td>
>> -      <td class="none" align="center">No</td>
>> +      <td class="full" align="center">SVN</td>
>>      </tr>
>>      <tr>
>>        <td><tt>[[nodiscard]]</tt> attribute</td>
>>
>>
>> _______________________________________________
>> cfe-commits mailing list
>> cfe-commits at lists.llvm.org
>> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
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