https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114990
--- Comment #9 from cqwrteur <unlvsur at live dot com> --- (In reply to Jason Merrill from comment #8) > bar.cppm:4:20: error: conflicting declaration of ‘void foo()’ in module ‘bar’ > 4 | export inline void foo() noexcept; > | ^~~ > In file included from bar.cppm:2: > someheader.hpp:1:13: note: previously declared in global module That is my problem. This just breaks header only libraries right? This is the same. import std; #include<aheaderonlylibrary> //it uses std features. This is absolutely the standard bug. I am 100% correct here.