[cfe-dev] Attempting to get type from typedef struct causes crash

[Stuart Thomson via cfe-dev]

Hi,

I am trying to write a custom clang-tidy check (I want to check for the use of CAdapt<>) but have been struggling with the following issue: I am trying to make an AST matcher which checks the string representation of the type of a VarDecl - but when it runs on certain code it crashes and I can't figure out why. The issue seems to be some interaction between QualType::getAsString() and typedef struct variables, (there may be other code which crashes it but this is what I have been able to find). The issue can be reproduced with the following custom clang-tidy check (apologies if there is a more sensible way to make a minimal repro than a clang-tidy check):

//-----------------------------------------------------------
#include "CrashingCheck.h"
#include "clang/AST/ASTContext.h"
#include "clang/ASTMatchers/ASTMatchFinder.h"

using namespace clang::ast_matchers;

namespace clang {
namespace tidy {
namespace misc {

    namespace {
        AST_MATCHER(VarDecl, isMatch) {
            Node.getTypeSourceInfo()->getType().getAsString();
            return false;
        }
    }

    void CrashingCheck::registerMatchers(MatchFinder *Finder) {
        Finder->addMatcher(varDecl(isMatch()).bind("varDecl"), this);
    }

    void CrashingCheck::check(const MatchFinder::MatchResult &Result) {}
}}}
//-----------------------------------------------------------

Which crashes when run on:

//-----------------------------------------------------------
typedef struct foo{} foo;

int main(){
    foo f;
    return 0;
}
//-----------------------------------------------------------

Is there some restriction on when it is OK to use getAsString() that I am not understanding? Also, if there is a better way to write something like this then do let me know, I'm pretty new to this.

Thanks,
Stuart
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