https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117419
--- Comment #4 from Richard Earnshaw <rearnsha at gcc dot gnu.org> --- enum size is ABI (affects data layout). So you can't use -f[no-]short-enums for executable tests. The best way to deal with this is to ensure that the size of the enum defaults to int (eg by adding a dummy enumeration value set to INT_MAX).