https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80163
--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> --- (In reply to Martin Liška from comment #2) > Clang rejects the test-case written in C: > > clang pr80163.c -c > pr80163.c:9:25: error: initializer element is not a compile-time constant > static __int128_t d = (long) &&a - (long) &&b; > ^~~~~~~~~~~~~~~~~~~~~~~ > 1 error generated. > > However accepts in C++: > > clang++ pr80163.cpp -c > [no output] We aren't talking about C++, that can construct those dynamically at runtime if they aren't constructible at compile time.