https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89090
--- Comment #2 from Csaba Ráduly <csaba_22 at yahoo dot co.uk> --- > Are you actually seeing a problem because of this? Not as such. What I did was to generate the pre-processed output, replace #s with // (so the line numbers are the raw ones for the raw preprocessed file) and compile it as if it were a regular C++ file. Then the compiler complained because the "if constexpr" didn't seem like part of a system header.
