How to enable a specific gcc warnings for a specific directory or file? [duplicate]

Question

Possible Duplicate:
Selectively disable GCC warnings for only part of a translation unit?

How to enable a specific gcc warnings for a specific directory or file ?

I want to enable -Wsign-conversion for my own files not for any other system headers

Answer 1

This line should do it: (see here)
#pragma GCC diagnostic warning "-Wsign-conversion"

Put it in the affected files or in a header that is included in all you files