Clang AST invalid type location

I am working on clang libtooling project for developing parser for C family of languages. I use clang front-end to parse the AST and get callbacks.

Now I found that for some unresolved types clang AST shows invalid declaration. So is there any way to get the actual type written in source file which clang is unable to resolve. Or alleast location of invalid types in AST.

This is really very important for me and I have spent a whole lot of time to get these clang thing work for me. Please help me to get out of this situation.

Thanks, Hemant