https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95699
--- Comment #6 from Jakub Jelinek <jakub at gcc dot gnu.org> --- I don't see why that should be considered a bug. All the tests are using __builtin_constant_p in a way that it wasn't designed for, where it changes the behavior of the program whether it evaluates to 0 or 1. The intended use of this builtin is to allow optimizations when something can be determined to be a compile time constant and have perhaps slower fallback that does the same thing, where e.g. the former can actually be much more expensive if it is not compile time constant and the latter e.g. a library call.
