https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66828
--- Comment #3 from Markus Trippelsdorf <trippels at gcc dot gnu.org> --- Well, gcc is a C++ project so the C99 standard doesn't apply. The C++ standard says: 5.8.2: The value of E1 << E2 is E1 left-shifted E2 bit positions; vacated bits are zero-filled. If E1 has an unsigned type, the value of the result is E1 × 2E2 , reduced modulo one more than the maximum value representable in the result type. Otherwise, if E1 has a signed type and non-negative value, and E1 × 2E2 is representable in the corresponding unsigned type of the result type, then that value, converted to the result type, is the resulting value; otherwise, the behavior is undefined.
