[PATCH][BZ #16004] Check overlaps in memcpy_chk.

[Ondřej Bílka]

On Sat, Oct 05, 2013 at 07:28:27PM +0000, Joseph S. Myers wrote:
> There are tests for *_chk functions in debug/.  If you add a new check you 
> should also add testcases for it to confirm that the error is caught at 
> runtime.  This does of course require also adding the same check to the 
> generic version of the function, and in the case of memcpy_chk to the x86 
> (32-bit) versions as well.
> 
It also requires to edit compile time check. I spend hour trying to
write testcase and wondering where is error until I realized that it got
optimized away at compile time.