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

[Baranov Victor via cfe-commits]

================
@@ -0,0 +1,319 @@
+//===--- 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/SmallVector.h"
+#include "llvm/ADT/Twine.h"
+#include <iterator>
+
+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->getName() == "lock_guard" && Decl->isInStdNamespace();
+    }
+  }
+
+  if (const auto *TemplateSpecType =
+          Type->getAs<TemplateSpecializationType>()) {
+    if (const TemplateDecl *Decl =
+            TemplateSpecType->getTemplateName().getAsTemplateDecl()) {
+      return Decl->getName() == "lock_guard" && Decl->isInStdNamespace();
+    }
+  }
+
+  return false;
+}
+
+llvm::SmallVector<const VarDecl *> getLockGuardsFromDecl(const DeclStmt *DS) {
+  llvm::SmallVector<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.
+llvm::SmallVector<llvm::SmallVector<const VarDecl *>>
+findLocksInCompoundStmt(const CompoundStmt *Block,
+                        const ast_matchers::MatchFinder::MatchResult &Result) {
+  // store groups of consecutive 'std::lock_guard' declarations
+  llvm::SmallVector<llvm::SmallVector<const VarDecl *>> LockGuardGroups;
+  llvm::SmallVector<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)) {
+      llvm::SmallVector<const VarDecl *> LockGuards = getLockGuardsFromDecl(DS);
+
+      if (!LockGuards.empty()) {
+        CurrentLockGuardGroup.insert(
+            CurrentLockGuardGroup.end(),
+            std::make_move_iterator(LockGuards.begin()),
+            std::make_move_iterator(LockGuards.end()));
+        continue;
+      }
+    }
+    AddAndClearCurrentGroup();
+  }
+
+  AddAndClearCurrentGroup();
+
+  return LockGuardGroups;
+}
+
+TemplateSpecializationTypeLoc
+getTemplateLockGuardTypeLoc(const TypeSourceInfo *SourceInfo) {
+  const TypeLoc Loc = SourceInfo->getTypeLoc();
+
+  const auto ElaboratedLoc = Loc.getAs<ElaboratedTypeLoc>();
+  if (!ElaboratedLoc)
+    return {};
+
+  return ElaboratedLoc.getNamedTypeLoc().getAs<TemplateSpecializationTypeLoc>();
+}
+
+// Find the exact source range of the 'lock_guard<...>' token
+SourceRange getLockGuardTemplateRange(const TypeSourceInfo *SourceInfo) {
+  const TemplateSpecializationTypeLoc TemplateLoc =
+      getTemplateLockGuardTypeLoc(SourceInfo);
+  if (!TemplateLoc)
+    return {};
+
+  return SourceRange(TemplateLoc.getTemplateNameLoc(),
+                     TemplateLoc.getRAngleLoc());
+}
+
+// Find the exact source range of the 'lock_guard' token
+SourceRange getLockGuardRange(const TypeSourceInfo *SourceInfo) {
+  const TemplateSpecializationTypeLoc TemplateLoc =
+      getTemplateLockGuardTypeLoc(SourceInfo);
+  if (!TemplateLoc)
+    return {};
+
+  return SourceRange(TemplateLoc.getTemplateNameLoc(),
+                     TemplateLoc.getLAngleLoc().getLocWithOffset(-1));
+}
+
+const StringRef UseScopedLockMessage =
+    "use 'std::scoped_lock' instead of 'std::lock_guard'";
+
+} // namespace
+
+UseScopedLockCheck::UseScopedLockCheck(StringRef Name,
+                                       ClangTidyContext *Context)
+    : ClangTidyCheck(Name, Context),
+      WarnOnSingleLocks(Options.get("WarnOnSingleLocks", true)),
+      WarnOnUsingAndTypedef(Options.get("WarnOnUsingAndTypedef", true)) {}
+
+void UseScopedLockCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
+  Options.store(Opts, "WarnOnSingleLocks", WarnOnSingleLocks);
+  Options.store(Opts, "WarnOnUsingAndTypedef", WarnOnUsingAndTypedef);
+}
+
+void UseScopedLockCheck::registerMatchers(MatchFinder *Finder) {
+  auto LockGuardClassDecl =
+      namedDecl(anyOf(classTemplateDecl(), classTemplateSpecializationDecl()),
+                hasName("lock_guard"), isInStdNamespace());
+  auto LockGuardType = qualType(hasDeclaration(LockGuardClassDecl));
+  auto LockVarDecl = varDecl(hasType(LockGuardType));
+
+  if (WarnOnSingleLocks) {
+    // Match CompoundStmt with only one 'std::lock_guard'
+    Finder->addMatcher(
+        compoundStmt(unless(isExpansionInSystemHeader()),
+                     has(declStmt(has(LockVarDecl.bind("lock-decl-single")))),
+                     unless(hasDescendant(declStmt(has(varDecl(
+                         hasType(LockGuardType),
+                         unless(equalsBoundNode("lock-decl-single")))))))),
+        this);
+  }
+
+  // Match CompoundStmt with multiple 'std::lock_guard'
+  Finder->addMatcher(
+      compoundStmt(unless(isExpansionInSystemHeader()),
+                   has(declStmt(has(LockVarDecl.bind("lock-decl-multiple")))),
+                   hasDescendant(declStmt(has(varDecl(
+                       hasType(LockGuardType),
+                       unless(equalsBoundNode("lock-decl-multiple")))))))
+          .bind("block-multiple"),
----------------
vbvictor wrote:

I added your example to _use-scoped-lock-warn-on-single-locks-false.cpp_ test file. In function `Negative()` does not have diag because `WarnOnSingleLocks` set to false.

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