https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95209
--- Comment #4 from M Welinder <terra at gnome dot org> --- Sorry about the missing "-v". It is indeed a x86_64-suse-linux system. (It's not internet facing or I'd go get the full output.) "Implementation defined", yes, but the implementation is the os, not the compiler/library. The OS gets to choose and, possibly, change its mind long after the compiler has written its output. > What meaning does //foo have on linux? Today, nothing separate, tomorrow who knows? The OS is at perfect liberty to assign a different meaning on Fridays if it so pleases. Run the linux binary on windows today and I suspect, but haven't verified, that it matters right now. Note that "cd //tmp" in bash shows that bash takes care not to mangle it.