Parsing comments with clang AST

Question

I would like to parse customized tag with clang AST. Here is a simple illustration of my compilation unit input.

#include <stdio.h>
int main() {
  // \my-tags tag_A, tag_B
  printf("helloworld");
  return 0;
}

How can I get those tags after \my-tags?

After reading clang user manual, I realize that -Wdocumentation, -fparse-all-comments or even -fcomment-block-commands may meet my requirement. However, when I add one of these flags in my compile_commands.json, the ASTContext.Comments.empty() still outputs True. I attach my compile_commands.json and my clang AST frontend code below for reference.

// compile_commands.json
[
  {
    "directory": "/home/my/project/target/directory",
    "arguments": ["/usr/local/bin/clang", "-c", "-std=c++14", "-Qunused-arguments", "-m64", "-fparse-all-comments", "-I/usr/include", "-I/usr/local/lib/clang/10.0.0/include", "-o", "build/.objs/input/linux/x86_64/release/target/target.cpp.o", "target/target.cpp"],
    "file": "target/target.cpp"
  }
]

// CommentParser.cpp
class MyPrinter : public MatchFinder::MatchCallback {
  public:
    virtual void run(const MatchFinder::MatchResult &Result) {
      ASTContext *Context = Result.Context;
      SourceManager& sm = Context->getSourceManager();
      if (!Context->Comments.empty())
        llvm::outs() << "There is no parsed comment\n";
    }
};

int main(int argc, const char **argv) {
  // CommonOptionsParser OptionsParser(argc, argv, MyToolCategory);
  std::string err;
  std::unique_ptr<CompilationDatabase> cd = CompilationDatabase::autoDetectFromSource("/home/my/project/target/directory/compile_commands.json", err);

  ClangTool Tool(*cd, cd->getAllFiles());

  MyPrinter Printer;
  MatchFinder Finder;

  StatementMatcher functionMatcher =
    callExpr(callee(functionDecl(hasName("pthread_mutex_lock")))).bind("functions");

  Finder.addMatcher(functionMatcher, &Printer);

  return Tool.run(newFrontendActionFactory(&Finder).get());
}

Answer 1

-fparse-all-comments works for me.

Maybe you can try not to use LibASTMatcher.

code example:

virtual void HandleTranslationUnit(clang::ASTContext& context) {
    auto comments = context.Comments.getCommentsInFile(
        context.getSourceManager().getMainFileID());
    llvm::outs() << context.Comments.empty() << "\n";
    ...
    for (auto it = comments->begin(); it != comments->end(); it++) {
      clang::RawComment* comment = it->second;
      std::string source = comment->getFormattedText(context.getSourceManager(),
          context.getDiagnostics());
      llvm::outs() << source << "\n";
    }
}

reference: https://clang.llvm.org/docs/RAVFrontendAction.html