https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95386
--- Comment #2 from Jiří Paleček <jpalecek at web dot de> --- (In reply to Martin Liška from comment #1) > Was the original code a valid code? > It seems the reduced code is invalid. Yes at least I believe so. I will attach the original code, it is not big. Note that you must compile (both versions) with -fconcepts.