https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96223
Richard Smith <richard-gccbugzilla at metafoo dot co.uk> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |richard-gccbugzilla@metafoo | |.co.uk --- Comment #2 from Richard Smith <richard-gccbugzilla at metafoo dot co.uk> --- P1331R2 explicitly disallows in a constant evaluation: "- an lvalue-to-rvalue conversion that is applied to an object with indeterminate value ([basic.indet]);" so GCC is correct to reject such cases.