I found https://gcc.gnu.org/onlinedocs/gccint/C-Tests.html which I then found better access to at https://github.com/gcc-mirror/gcc/tree/master/gcc/testsuite (the first link is actually talking about the gcc.dg subdirectory of the second). Lots of stuff in there so I didn't go trawling through there trying to guess if any of it might suite your needs.

A compliance test suite would be a nice addition to something that has such a robust standard defined for it. I thought that was a fairly common thing for those old-style standards where you have to pay to get an official copy.