https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80756
nsz at gcc dot gnu.org changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |nsz at gcc dot gnu.org --- Comment #3 from nsz at gcc dot gnu.org --- fabs and fma identifiers are reserved for the implementation and it is valid to treat them as constant expression in initializers based on c99 6.6p10 i think the gcc behaviour is reasonable.