[clang-tidy]

 modernize-use-cpp-style-comments check finds C style comments and suggests to use C++ style comments Fixes #24841

Author: chaitanyav

clang-tools-extra/clang-tidy/modernize/CMakeLists.txt

@@ -31,6 +31,7 @@ add_clang_library(clangTidyModernizeModule
  UseAutoCheck.cpp
  UseBoolLiteralsCheck.cpp
  UseConstraintsCheck.cpp
+ UseCppStyleCommentsCheck.cpp
  UseDefaultMemberInitCheck.cpp
  UseDesignatedInitializersCheck.cpp
  UseEmplaceCheck.cpp

clang-tools-extra/clang-tidy/modernize/ModernizeTidyModule.cpp

@@ -32,6 +32,7 @@
 #include "UseAutoCheck.h"
 #include "UseBoolLiteralsCheck.h"
 #include "UseConstraintsCheck.h"
+#include "UseCppStyleCommentsCheck.h"
 #include "UseDefaultMemberInitCheck.h"
 #include "UseDesignatedInitializersCheck.h"
 #include "UseEmplaceCheck.h"
@@ -104,6 +105,8 @@ class ModernizeModule : public ClangTidyModule {
  "modernize-use-bool-literals");
  CheckFactories.registerCheck<UseConstraintsCheck>(
  "modernize-use-constraints");
+ CheckFactories.registerCheck<UseCppStyleCommentsCheck>(
+ "modernize-use-cpp-style-comments");
  CheckFactories.registerCheck<UseDefaultMemberInitCheck>(
  "modernize-use-default-member-init");
  CheckFactories.registerCheck<UseEmplaceCheck>("modernize-use-emplace");

clang-tools-extra/clang-tidy/modernize/UseCppStyleCommentsCheck.cpp

@@ -0,0 +1,66 @@
+//===--- UseCppStyleCommentsCheck.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 "UseCppStyleCommentsCheck.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/Lex/Lexer.h"
+#include "clang/Lex/Preprocessor.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang::tidy::modernize {
+
+class UseCppStyleCommentsCheck::CStyleCommentHandler : public CommentHandler {
+public:
+ CStyleCommentHandler(UseCppStyleCommentsCheck &Check)
+ : Check(Check),
+ CStyleCommentMatch(
+ "^[ \t]*/\\*+[ \t\n]*(.*[ \t\n]*)*[ \t\n]*\\*+/[ \t\n]*$") {}
+
+ bool HandleComment(Preprocessor &PP, SourceRange Range) override {
+
+ if (Range.getBegin().isMacroID() ||
+ PP.getSourceManager().isInSystemHeader(Range.getBegin()))
+ return false;
+
+ const StringRef Text =
+ Lexer::getSourceText(CharSourceRange::getCharRange(Range),
+ PP.getSourceManager(), PP.getLangOpts());
+
+ SmallVector<StringRef> Matches;
+ if (!CStyleCommentMatch.match(Text, &Matches)) {
+ return false;
+ }
+
+ Check.diag(
+ Range.getBegin(),
+ "use C++ style comments '//' instead of C style comments '/*...*/'")
+ << FixItHint::CreateRemoval(CharSourceRange::getCharRange(Range));
+
+ return false;
+ }
+
+private:
+ UseCppStyleCommentsCheck &Check;
+ llvm::Regex CStyleCommentMatch;
+};
+
+UseCppStyleCommentsCheck::UseCppStyleCommentsCheck(StringRef Name,
+ ClangTidyContext *Context)
+ : ClangTidyCheck(Name, Context),
+ Handler(std::make_unique<CStyleCommentHandler>(*this)) {}
+
+void UseCppStyleCommentsCheck::registerPPCallbacks(
+ const SourceManager &SM, Preprocessor *PP, Preprocessor *ModuleExpanderPP) {
+ PP->addCommentHandler(Handler.get());
+}
+
+void UseCppStyleCommentsCheck::check(const MatchFinder::MatchResult &Result) {}
+
+UseCppStyleCommentsCheck::~UseCppStyleCommentsCheck() = default;

clang-tools-extra/clang-tidy/modernize/UseCppStyleCommentsCheck.h

@@ -0,0 +1,38 @@
+//===--- UseCppStyleCommentsCheck.h - 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MODERNIZE_USE_CPP_STYLE_COMMENTS_CHECK_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MODERNIZE_USE_CPP_STYLE_COMMENTS_CHECK_H
+
+#include "../ClangTidyCheck.h"
+
+namespace clang::tidy::modernize {
+/// detects C-style comments and suggests to use C++ style comments instead
+///
+/// For the user-facing documentation see:
+/// http://clang.llvm.org/extra/clang-tidy/checks/modernize/use-cpp-style-comments.html
+class UseCppStyleCommentsCheck : public ClangTidyCheck {
+public:
+ UseCppStyleCommentsCheck(StringRef Name, ClangTidyContext *Context);
+ ~UseCppStyleCommentsCheck() override;
+
+ bool isLanguageVersionSupported(const LangOptions &LangOpts) const override {
+ return LangOpts.CPlusPlus;
+ }
+
+ void registerPPCallbacks(const SourceManager &SM, Preprocessor *PP,
+ Preprocessor *ModuleExpanderPP) override;
+ void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+
+private:
+ class CStyleCommentHandler;
+ std::unique_ptr<CStyleCommentHandler> Handler;
+};
+} // namespace clang::tidy::modernize
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MODERNIZE_USE_CPP_STYLE_COMMENTS_CHECK_H

clang-tools-extra/docs/ReleaseNotes.rst

@@ -172,6 +172,11 @@ New checks
  Detects variables and functions that can be marked as static or moved into
  an anonymous namespace to enforce internal linkage.
 
+- New :doc:`modernize-use-cpp-style-comments
+ <clang-tidy/checks/modernize/use-cpp-style-comments>` check.
+
+ Find C Style comments and suggests to use C++ style comments instead
+
 - New :doc:`modernize-min-max-use-initializer-list
  <clang-tidy/checks/modernize/min-max-use-initializer-list>` check.
 

clang-tools-extra/docs/clang-tidy/checks/modernize/use-cpp-style-comments.rst

@@ -0,0 +1,12 @@
+.. title:: clang-tidy - modernize-use-cpp-style-comments
+
+modernize-use-cpp-style-comments
+================================
+
+Finds C-style comments and suggests to use C++ style comments `//`.
+
+
+.. code-block:: c++
+
+ memcpy(a, b, sizeof(int) * 5); /* use std::copy_n instead of memcpy */
+ // warning: use C++ style comments '//' instead of C style comments '/*...*/' [modernize-use-cpp-style-comments]

clang-tools-extra/test/clang-tidy/checkers/modernize/use-cpp-style-comments.cpp

@@ -0,0 +1,16 @@
+// RUN: %check_clang_tidy -std=c++11 %s modernize-use-cpp-style-comments %t
+
+static auto PI = 3.14159265; /* value of pi upto 8 decimal places */
+// CHECK-MESSAGES: :[[@LINE-1]]:30: warning: use C++ style comments '//' instead of C style comments '/*...*/' [modernize-use-cpp-style-comments]
+
+/******************************************************
+* Fancy frame comment goes here
+*******************************************************/
+// CHECK-MESSAGES: :[[@LINE-3]]:1: warning: use C++ style comments '//' instead of C style comments '/*...*/' [modernize-use-cpp-style-comments]
+
+/** \brief Brief description.
+ * Brief description continued.
+ *
+ * Detailed description starts here. (this is a doxygen comment)
+ */
+// CHECK-MESSAGES: :[[@LINE-5]]:1: warning: use C++ style comments '//' instead of C style comments '/*...*/' [modernize-use-cpp-style-comments]