This commit is to resolve the issue llvm#24841

Author: chaitanyav

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

@@ -31,6 +31,7 @@ add_clang_library(clangTidyModernizeModule STATIC
   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"
@@ -107,6 +108,8 @@ 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 +1,126 @@
+//===--- 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"
+#include <iostream>
+using namespace clang::ast_matchers;
+
+namespace clang::tidy::modernize {
+class UseCppStyleCommentsCheck::CStyleCommentHandler : public CommentHandler {
+public:
+  CStyleCommentHandler(UseCppStyleCommentsCheck &Check)
+      : Check(Check),
+        CStyleCommentMatch(
+                          "^[ \t]*/\\*+[ \t\r\n]*(.*[ \t\r\n]*)*[ \t\r\n]*\\*+/[ \t\r\n]*$"){}
+
+  std::string convertToCppStyleComment(const SourceManager &SM, const SourceRange &Range) {
+    StringRef CommentText = Lexer::getSourceText(
+        CharSourceRange::getTokenRange(Range), SM, LangOptions());
+
+    std::string InnerText = CommentText.str();
+    InnerText.erase(0, 2);
+    InnerText.erase(InnerText.size() - 2, 2);
+
+    std::string Result;
+    std::istringstream Stream(InnerText);
+    std::string Line;
+
+    if (std::getline(Stream, Line)) {
+      size_t startPos = Line.find_first_not_of(" \t");
+      if (startPos != std::string::npos) {
+          Line = Line.substr(startPos);
+      } else {
+          Line.clear();
+      }
+      Result += "// " + Line;
+    }
+
+    while (std::getline(Stream, Line)) {
+    size_t startPos = Line.find_first_not_of(" \t");
+      if (startPos != std::string::npos) {
+          Line = Line.substr(startPos);
+      } else {
+          Line.clear();
+      }
+      Result += "\n// " + Line;
+    }
+    return Result;
+  }
+
+  bool HandleComment(Preprocessor &PP, SourceRange Range) override {
+    const SourceManager &SM = PP.getSourceManager();
+
+    if (Range.getBegin().isMacroID() ||
+        SM.isInSystemHeader(Range.getBegin())) {
+        return false;
+    }
+
+    const StringRef Text =
+        Lexer::getSourceText(CharSourceRange::getCharRange(Range),
+                             SM, PP.getLangOpts());
+
+    SmallVector<StringRef> Matches;
+    if (!CStyleCommentMatch.match(Text, &Matches)) {
+        return false;
+    }
+
+    SourceLocation CommentStart = Range.getBegin();
+    SourceLocation CommentEnd = Range.getEnd();
+
+    unsigned StartLine = SM.getSpellingLineNumber(CommentStart);
+    unsigned EndLine = SM.getSpellingLineNumber(CommentEnd);
+
+   
+    if (StartLine == EndLine) {
+      SourceLocation LineBegin = SM.translateLineCol(
+          SM.getFileID(CommentStart), StartLine, 1);
+      SourceLocation LineEnd = SM.translateLineCol(SM.getFileID(CommentEnd), EndLine, std::numeric_limits<unsigned>::max());
+      StringRef LineContent =
+          Lexer::getSourceText(CharSourceRange::getCharRange(LineBegin, LineEnd),
+                              SM, PP.getLangOpts());
+      size_t CommentStartOffset = SM.getSpellingColumnNumber(CommentStart) - 1;
+      StringRef AfterComment = LineContent.drop_front(CommentStartOffset + Text.size());
+
+      if (!AfterComment.trim().empty()) {
+          return false;
+      }
+    }
+    
+    Check.diag(
+        Range.getBegin(),
+        "use C++ style comments '//' instead of C style comments '/*...*/'")
+        << clang::FixItHint::CreateReplacement(
+               Range, convertToCppStyleComment(SM, 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;
+} // namespace clang::tidy::modernize

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

@@ -0,0 +1,40 @@
+//===--- 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"
+#include <sstream>
+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