I don't have the whole list of GCC binaries available so I determined the exact
version where the warning disappeared via:
https://github.com/gcc-mirror/gcc/blob/gcc-4_9_0-release/gcc/cp/typeck.c#L6863
https://github.com/gcc-mirror/gcc/blob/gcc-4_8_5-release/gcc/cp/typeck.c#L6652
Clang itself defines these as 4.2, so I don't think we want to disable this warning for clang. I think there needs to be a !defined(__clang) &&...