https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117215
Andrew Pinski <pinskia at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Resolution|--- |DUPLICATE Status|UNCONFIRMED |RESOLVED --- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> --- ............... nagisa/include/nagisa/stl_freestanding/utility/./detail/./environment.h ................ nagisa/include/nagisa/stl_freestanding/utility/./detail/../environment.h This is not exactly a bug but the issue is you have some files with `#pragma once` which are exactly the same contents which GCC decides is the same (from a definition of the once it is correct). So you should stop using `#pragma once` if you have files which are the same contents. In this case environment.h is: ``` #pragma once #include "../environment.h" ``` But that is a few different environment.h files too. *** This bug has been marked as a duplicate of bug 52566 ***