I have seen with clang++ that if I mix and match .o files built with -std=c++11 and -std=c++17 [something I have occasionally done by accident] and they referen

I have seen with clang++ that if I mix and match .o files built with -std=c++11 and -std=c++17 [something I have occasionally done by accident] and they reference the same classes, sometimes they fail to link, not due to standard library types differing but ones I defined myself that can compile with either standard.