https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89808
--- Comment #4 from sduguay <s_gcc_bugzilla at binarez dot com> --- (In reply to Jakub Jelinek from comment #2) > You haven't explained why do you need to use #pragma once in the main cpp > source file, are you sometimes including it as a header and other times > compiling it as the TU itself? Not to mention that it is best not to use > #pragma once at all anywhere. Yes, in the system I'm working on, there is no "main file", all C++ (xcpp files actually) are small C++ programs that I link with a generated main file. xcpp programs can use other programs (xcpp files) or libs (xhpp files). This is all working pretty well right now, except for that #pragma once warning. It's still under pretty heavy development. You can try it @ https://github.com/binarez/xcpp Thanks