[clang-tools-extra] [clang-tidy] add new check: modernize-use-scoped-lock (PR #126434)

[Piotr Zegar via cfe-commits]

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@@ -0,0 +1,233 @@
+//===--- UseScopedLockCheck.cpp - clang-tidy ------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "UseScopedLockCheck.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/AST/Decl.h"
+#include "clang/AST/Stmt.h"
+#include "clang/AST/Type.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/ASTMatchers/ASTMatchers.h"
+#include "clang/Basic/SourceLocation.h"
+#include "clang/Lex/Lexer.h"
+#include "llvm/ADT/Twine.h"
+#include <iterator>
+#include <optional>
+
+using namespace clang::ast_matchers;
+
+namespace clang::tidy::modernize {
+
+namespace {
+
+bool isLockGuard(const QualType &Type) {
+  if (const auto *Record = Type->getAs<RecordType>()) {
+    if (const RecordDecl *Decl = Record->getDecl()) {
+      return Decl->getQualifiedNameAsString() == "std::lock_guard";
+    }
+  }
+
+  if (const auto *TemplateSpecType =
+          Type->getAs<TemplateSpecializationType>()) {
+    if (const TemplateDecl *Decl =
+            TemplateSpecType->getTemplateName().getAsTemplateDecl()) {
+      return Decl->getQualifiedNameAsString() == "std::lock_guard";
+    }
+  }
+
+  return false;
+}
+
+std::vector<const VarDecl *> getLockGuardsFromDecl(const DeclStmt *DS) {
+  std::vector<const VarDecl *> LockGuards;
+
+  for (const Decl *Decl : DS->decls()) {
+    if (const auto *VD = dyn_cast<VarDecl>(Decl)) {
+      const QualType Type = VD->getType().getCanonicalType();
+      if (isLockGuard(Type)) {
+        LockGuards.push_back(VD);
+      }
+    }
+  }
+
+  return LockGuards;
+}
+
+// Scans through the statements in a block and groups consecutive
+// 'std::lock_guard' variable declarations together.
+std::vector<std::vector<const VarDecl *>>
+findLocksInCompoundStmt(const CompoundStmt *Block,
+                        const ast_matchers::MatchFinder::MatchResult &Result) {
+  // store groups of consecutive 'std::lock_guard' declarations
+  std::vector<std::vector<const VarDecl *>> LockGuardGroups;
+  std::vector<const VarDecl *> CurrentLockGuardGroup;
+
+  auto AddAndClearCurrentGroup = [&]() {
+    if (!CurrentLockGuardGroup.empty()) {
+      LockGuardGroups.push_back(CurrentLockGuardGroup);
+      CurrentLockGuardGroup.clear();
+    }
+  };
+
+  for (const Stmt *Stmt : Block->body()) {
+    if (const auto *DS = dyn_cast<DeclStmt>(Stmt)) {
+      std::vector<const VarDecl *> LockGuards = getLockGuardsFromDecl(DS);
+
+      if (!LockGuards.empty()) {
+        CurrentLockGuardGroup.insert(
+            CurrentLockGuardGroup.end(),
+            std::make_move_iterator(LockGuards.begin()),
+            std::make_move_iterator(LockGuards.end()));
+      }
+
+      if (LockGuards.empty()) {
+        AddAndClearCurrentGroup();
+      }
+    } else {
+      AddAndClearCurrentGroup();
+    }
+  }
+
+  AddAndClearCurrentGroup();
+
+  return LockGuardGroups;
+}
+
+// Find the exact source range of the 'lock_guard<...>' token
+std::optional<SourceRange> getLockGuardRange(const VarDecl *LockGuard,
+                                             SourceManager &SM) {
+  const TypeSourceInfo *SourceInfo = LockGuard->getTypeSourceInfo();
+  const TypeLoc Loc = SourceInfo->getTypeLoc();
+
+  const auto ElaboratedLoc = Loc.getAs<ElaboratedTypeLoc>();
+  if (!ElaboratedLoc)
+    return std::nullopt;
+
+  const auto TemplateLoc =
+      ElaboratedLoc.getNamedTypeLoc().getAs<TemplateSpecializationTypeLoc>();
+  if (!TemplateLoc)
+    return std::nullopt;
+
+  const SourceLocation LockGuardBeginLoc = TemplateLoc.getTemplateNameLoc();
+  const SourceLocation LockGuardRAngleLoc = TemplateLoc.getRAngleLoc();
+
+  return SourceRange(LockGuardBeginLoc, LockGuardRAngleLoc);
+}
+
+} // namespace
+
+void UseScopedLockCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
+  Options.store(Opts, "WarnOnlyMultipleLocks", WarnOnlyMultipleLocks);
+}
+
+void UseScopedLockCheck::registerMatchers(MatchFinder *Finder) {
+  auto LockGuardType = qualType(hasDeclaration(namedDecl(
+      hasName("::std::lock_guard"),
+      anyOf(classTemplateDecl(), classTemplateSpecializationDecl()))));
+  auto LockVarDecl = varDecl(hasType(LockGuardType));
+
+  // Match CompoundStmt with only one 'std::lock_guard'
+  if (!WarnOnlyMultipleLocks) {
+    Finder->addMatcher(
+        compoundStmt(has(declStmt(has(LockVarDecl.bind("lock-decl-single")))),
----------------
PiotrZSL wrote:

consider excluding system headers

https://github.com/llvm/llvm-project/pull/126434