[clang-tidy] Replace /* ... */ single-line comments with // ... comments

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

@@ -57,6 +57,7 @@ add_clang_library(clangTidyReadabilityModule STATIC
   UniqueptrDeleteReleaseCheck.cpp
   UppercaseLiteralSuffixCheck.cpp
   UseAnyOfAllOfCheck.cpp
+  UseCppStyleCommentsCheck.cpp
   UseStdMinMaxCheck.cpp
 
   LINK_LIBS

clang-tools-extra/clang-tidy/readability/ReadabilityTidyModule.cpp

@@ -60,6 +60,7 @@
 #include "UniqueptrDeleteReleaseCheck.h"
 #include "UppercaseLiteralSuffixCheck.h"
 #include "UseAnyOfAllOfCheck.h"
+#include "UseCppStyleCommentsCheck.h"
 #include "UseStdMinMaxCheck.h"
 
 namespace clang::tidy {
@@ -170,6 +171,8 @@ class ReadabilityModule : public ClangTidyModule {
         "readability-uppercase-literal-suffix");
     CheckFactories.registerCheck<UseAnyOfAllOfCheck>(
         "readability-use-anyofallof");
+    CheckFactories.registerCheck<UseCppStyleCommentsCheck>(
+        "readability-use-cpp-style-comments");
     CheckFactories.registerCheck<UseStdMinMaxCheck>(
         "readability-use-std-min-max");
   }

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

@@ -0,0 +1,149 @@
+//===--- 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 <sstream>
+
+using namespace clang::ast_matchers;
+
+namespace clang::tidy::readability {
+class UseCppStyleCommentsCheck::CStyleCommentHandler : public CommentHandler {
+public:
+  CStyleCommentHandler(UseCppStyleCommentsCheck &Check, bool ExcludeDoxygen)
+      : Check(Check), ExcludeDoxygen(ExcludeDoxygen),
+        CStyleCommentMatch(
+            "^[ \t]*/\\*+[ \t\r\n]*(.*[ \t\r\n]*)*[ \t\r\n]*\\*+/[ \t\r\n]*$") {
+  }
+
+  void setExcludeDoxygen(bool Exclude) { ExcludeDoxygen = Exclude; }
+
+  bool isExcludeDoxygen() const { return ExcludeDoxygen; }
+
+  std::string convertToCppStyleComment(const SourceManager &SM,
+                                       const SourceRange &Range) {
+    const 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)) {
+      const 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)) {
+      const 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 isDoxygenStyleComment(const StringRef &Text) {
+    StringRef Trimmed = Text.ltrim();
+    return Trimmed.starts_with("/**") || Trimmed.starts_with("/*!") ||
+           Trimmed.starts_with("///") || Trimmed.starts_with("//!") ||
+           (Trimmed.starts_with("/*") &&
+            Trimmed.drop_front(2).starts_with("*"));
+  }
+
+  bool CheckForTextAfterComment(Preprocessor &PP, SourceRange Range) {
+    const SourceManager &SM = PP.getSourceManager();
+    const SourceLocation CommentEnd = Range.getEnd();
+
+    unsigned EndLine = SM.getSpellingLineNumber(CommentEnd);
+    unsigned EndCol = SM.getSpellingColumnNumber(CommentEnd);
+
+    const SourceLocation LineBegin =
+        SM.translateLineCol(SM.getFileID(CommentEnd), EndLine, EndCol);
+    const SourceLocation LineEnd =
+        SM.translateLineCol(SM.getFileID(CommentEnd), EndLine,
+                            std::numeric_limits<unsigned>::max());
+    const StringRef AfterComment =
+        Lexer::getSourceText(CharSourceRange::getCharRange(LineBegin, LineEnd),
+                             SM, PP.getLangOpts());
+
+    return !AfterComment.trim().empty();
+  }
+
+  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());
+
+    if (ExcludeDoxygen && isDoxygenStyleComment(Text)) {
+      return false;
+    }
+
+    SmallVector<StringRef> Matches;
+    if (!CStyleCommentMatch.match(Text, &Matches)) {
+      return false;
+    }
+
+    if (CheckForTextAfterComment(PP, Range)) {
+      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;
+  bool ExcludeDoxygen;
+  llvm::Regex CStyleCommentMatch;
+};
+
+UseCppStyleCommentsCheck::UseCppStyleCommentsCheck(StringRef Name,
+                                                   ClangTidyContext *Context)
+    : ClangTidyCheck(Name, Context),
+      Handler(std::make_unique<CStyleCommentHandler>(
+          *this, Options.get("ExcludeDoxygenStyleComments", false))) {}
+
+void UseCppStyleCommentsCheck::registerPPCallbacks(
+    const SourceManager &SM, Preprocessor *PP, Preprocessor *ModuleExpanderPP) {
+  PP->addCommentHandler(Handler.get());
+}
+
+void UseCppStyleCommentsCheck::check(const MatchFinder::MatchResult &Result) {}
+
+void UseCppStyleCommentsCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
+  Options.store(Opts, "ExcludeDoxygenStyleComments",
+                Handler->isExcludeDoxygen());
+}
+
+UseCppStyleCommentsCheck::~UseCppStyleCommentsCheck() = default;
+} // namespace clang::tidy::readability

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

@@ -0,0 +1,47 @@
+//===--- UseCppStyleCommentsCheck.h - clang-tidy-----------------*- C++ -*-===//
+//
+// 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_READABILITY_USECPPSTYLECOMMENTSCHECK_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_USECPPSTYLECOMMENTSCHECK_H
+
+#include "../ClangTidyCheck.h"
+#include <memory>
+
+namespace clang::tidy::readability {
+/// Detects C Style comments and suggests to use C++ style comments instead.
+///
+/// Optionally excludes Doxygen-style comments.
+///
+/// For the user-facing documentation see:
+/// http://clang.llvm.org/extra/clang-tidy/checks/readability/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;
+
+  void storeOptions(ClangTidyOptions::OptionMap &Opts) override;
+
+private:
+  class CStyleCommentHandler;
+  std::unique_ptr<CStyleCommentHandler> Handler;
+  const bool ExcludeDoxygenStyleComments =
+      Options.get("ExcludeDoxygenStyleComments", false);
+};
+} // namespace clang::tidy::readability
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_USECPPSTYLECOMMENTSCHECK_H

clang-tools-extra/docs/ReleaseNotes.rst

@@ -91,6 +91,11 @@ Improvements to clang-tidy
 New checks
 ^^^^^^^^^^
 
+- New :doc:`readability-use-cpp-style-comments
+  <clang-tidy/checks/readability/use-cpp-style-comments>` check.
+
+  Replace C-style comments with C++-style comments.
+
 New check aliases
 ^^^^^^^^^^^^^^^^^
 

clang-tools-extra/docs/clang-tidy/checks/list.rst

@@ -403,6 +403,7 @@ Clang-Tidy Checks
    :doc:`readability-uniqueptr-delete-release <readability/uniqueptr-delete-release>`, "Yes"
    :doc:`readability-uppercase-literal-suffix <readability/uppercase-literal-suffix>`, "Yes"
    :doc:`readability-use-anyofallof <readability/use-anyofallof>`,
+   :doc:`readability-use-cpp-style-comments <readability/use-cpp-style-comments>`, "Yes"
    :doc:`readability-use-std-min-max <readability/use-std-min-max>`, "Yes"
    :doc:`zircon-temporary-objects <zircon/temporary-objects>`,
 

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

@@ -0,0 +1,51 @@
+.. title:: clang-tidy - use-cpp-style-comments
+
+readability-use-cpp-style-comments
+==================================
+
+Replace C-style comments with C++-style comments.
+C-style comments (``/* ... */``) are inherited from C, while C++ introduces 
+``//`` as a more concise, readable, and less error-prone alternative. Modern C++ 
+guidelines recommend using C++-style comments for consistency and 
+maintainability. This check identifies and replaces C-style comments with 
+equivalent C++-style comments.
+
+Examples:
+
+Input:
+
+.. code-block::c++
+
+  /* This is a single-line comment */
+  int x = 42;  /* Inline comment */
+
+  /* This is a
+  multi-line comment */
+
+Output:
+
+.. code-block::c++
+
+  // This is a single-line comment
+  int x = 42;  // Inline comment
+
+  // This is a
+  // multi-line comment
+
+.. note::
+
+  Inline Comments are neither fixed nor warned.
+
+  Example:
+
+  .. code-block:: c++
+
+    int a = /* this is a comment */ 5;
+
+Options
+-------
+
+.. option:: ExcludeDoxygenStyleComments
+
+   A boolean option that determines whether Doxygen-style comments should be excluded.  
+   By default, this option is set to ``false``.  

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

@@ -0,0 +1,34 @@
+// RUN: %check_clang_tidy -std=c++11 %s readability-use-cpp-style-comments %t -config="{CheckOptions: [{key: readability-use-cpp-style-comments.ExcludeDoxygenStyleComments, value: true}]}"
+
+// Tests for Doxygen comments with ExcludeDoxygenStyleComments enabled
+/**
+ * This is a Doxygen comment for a function.
+ * It should NOT be transformed.
+ */
+void doxygenFunction1();
+
+/*!
+ * This is another Doxygen-style comment.
+ * It should also NOT be transformed.
+ */
+void doxygenFunction2();
+
+/**
+ * Multiline Doxygen comment describing parameters.
+ *
+ * @param x The first parameter.
+ * @param y The second parameter.
+ * @return A result value.
+ */
+int doxygenFunctionWithParams(int x, int y);
+
+/*******************************
+ * Non-Doxygen block comments without markers
+ *******************************/
+void DoxygenBlock();
+
+/*!
+ * This is a single-line Doxygen comment.
+ * Should NOT be transformed.
+ */
+void singleLineDoxygen();

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

@@ -0,0 +1,68 @@
+// RUN: %check_clang_tidy -std=c++11 %s readability-use-cpp-style-comments %t 
+
+// Single-line full C-style comment
+static const int CONSTANT = 42; /* Important constant value */
+// CHECK-MESSAGES: :[[@LINE-1]]:33: warning: use C++ style comments '//' instead of C style comments '/*...*/' [readability-use-cpp-style-comments]
+// CHECK-FIXES: static const int CONSTANT = 42; // Important constant value
+
+// Inline comment that should NOT be transformed
+int a = /* inline comment */ 5;
+
+// Multiline full-line comment
+/* This is a multiline comment
+   that spans several lines
+   and should be converted to C++ style */
+// CHECK-MESSAGES: :[[@LINE-3]]:1: warning: use C++ style comments '//' instead of C style comments '/*...*/' [readability-use-cpp-style-comments]
+// CHECK-FIXES: // This is a multiline comment
+// CHECK-FIXES: // that spans several lines
+// CHECK-FIXES: // and should be converted to C++ style
+void fnWithSomeBools(bool A,bool B) {}
+// Function with parameter inline comments
+void processData(int data /* input data */, 
+                 bool validate /* perform validation */) {
+    // These inline comments should NOT be transformed
+    fnWithSomeBools(/*ControlsA=*/ true, /*ControlsB=*/ false);
+}
+
+int calculateSomething() { return 1;}
+// Comment at end of complex line
+int complexCalculation = calculateSomething(); /* Result of complex calculation */
+// CHECK-MESSAGES: :[[@LINE-1]]:48: warning: use C++ style comments '//' instead of C style comments '/*...*/' [readability-use-cpp-style-comments]
+// CHECK-FIXES: int complexCalculation = calculateSomething(); // Result of complex calculation
+
+// Nested comments and edge cases
+void edgeCaseFunction() {
+    int x = 10 /* First value */ + 20 /* Second value */;  // Inline comments should not transform
+
+    /* Comment with special characters !@#$%^&*()_+ */
+    // CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use C++ style comments '//' instead of C style comments '/*...*/' [readability-use-cpp-style-comments]
+    // CHECK-FIXES: // Comment with special characters !@#$%^&*()_+
+}
+
+// Multiline comment with various indentations
+    /* This comment is indented
+       and should preserve indentation when converted */
+// CHECK-MESSAGES: :[[@LINE-2]]:5: warning: use C++ style comments '//' instead of C style comments '/*...*/' [readability-use-cpp-style-comments]
+// CHECK-FIXES:     // This comment is indented
+// CHECK-FIXES:     // and should preserve indentation when converted
+
+// Complex function with mixed comment types
+void complexFunction() {
+    /* Full line comment at start of block */
+    // CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use C++ style comments '//' instead of C style comments '/*...*/' [readability-use-cpp-style-comments]
+    // CHECK-FIXES: // Full line comment at start of block
+
+    int x = 10; /* Inline comment not to be transformed */
+    // CHECK-MESSAGES: :[[@LINE-1]]:17: warning: use C++ style comments '//' instead of C style comments '/*...*/' [readability-use-cpp-style-comments]
+    // CHECK-FIXES: int x = 10; // Inline comment not to be transformed
+}
+
+/* aaa 
+    bbbb
+    ccc */ int z = 1;
+// There is a text after the comment ends so it should be ignored.
+
+int y = 10;/* aaa 
+    bbbb
+    ccc */ int z1 = 1;
+// There is a text after the comment ends so it should be ignored.