https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97665
--- Comment #9 from Andrew Pinski <pinskia at gcc dot gnu.org> --- The array is not needed to reproduce this though: struct Foo { constexpr Foo() {} }; union U { // struct {} monostate = {}; Foo foo; constexpr U() {} }; constexpr U s;