Dumping variables declared as __attribute__((unused)) are dumped incorrectly.

[giulianobelinassi]

Given the following code:

#include "clang/Frontend/CompilerInstance.h"
#include "clang/Tooling/Tooling.h"

using namespace clang;
using namespace llvm;

std::string Output_AST(ASTUnit *ast)
{
  std::string ret;
  raw_string_ostream ostream(ret);

  for (auto it = ast->top_level_begin(); it != ast->top_level_end(); ++it) {
    Decl *decl = *it;
    decl->print(ostream, PrintingPolicy(LangOptions()));
  }

  return ret;
}

static const char *const code =
"int main() {\n"
"    int x __attribute__((unused)) = 0;\n"
"    return 0;\n"
"}\n";

int main(int argc, char **argv)
{
  std::unique_ptr<ASTUnit> ast = tooling::buildASTFromCode(code);

  std::string output = Output_AST(ast.get());

  if (output != code) {
    llvm::outs() << "Code output by Output_AST:" << '\n'
                 << output;
    return 1;
  }

  return 0;
}

The correct output would be exactly what code variable described, instead of having as output in Output_AST

 int x = 0 __attribute__((unused));

which Clang parser rejects.

[AaronBallman]

You can see this with -ast-print as well: https://godbolt.org/z/vbePnv3r3

[giulianobelinassi]

A fix for this case has been proposed, but it doesn't cover all possible cases: https://reviews.llvm.org/D141714

[AaronBallman]

Ah, thank you for posting that link, I was just making the same change locally. I'll review on that thread.