https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88395
--- Comment #11 from Nicholas Krause <xerofoify at gmail dot com> --- (In reply to Jason Merrill from comment #10) > I don't think this is a valid testcase: operator+= requires Concept, but > checking Concept depends on operator+=. It would be good for the compiler > to detect this recursive dependency rather than recursing infinitely, of > course. I agree however I was going to test on clang but seems clang does not support concepts yet so didn't know if it would crash on that too. Still a nullptr on concepts expansion isn't good. Perhaps a better idea would be to warn about the infinite expansion than my PARM_CONSTR patch posted previously.
