https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98549
--- Comment #14 from Segher Boessenkool <segher at gcc dot gnu.org> --- (In reply to Jakub Jelinek from comment #13) > For UB at runtime, we can warn, but shouldn't error because the code might > never be invoked at runtime. As far as I can see at least the C standard disagrees with this: NOTE Possible undefined behavior ranges from ignoring the situation completely with unpredictable results, to behaving during translation or program execution in a documented manner characteristic of the environment (with or without the issuance of a diagnostic message), to terminating a translation or execution (with the issuance of a diagnostic message). So we are allowed to error. It doesn't seem we will ever agree whether this is valid code. This is not a very useful discussion anyway: let's just make a small (valid code) testcase and be done with it :-)
