https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108108
--- Comment #4 from M Welinder <terra at gnome dot org> --- > Since it was not read again, the file is not considered included ... It must have been read -- how else could gcc decide it was the same? # strace -f gcc -MM c.c 2>&1 >Makefile | grep 'open.*\.h' | grep -v / [pid 30494] openat(AT_FDCWD, "a.h", O_RDONLY|O_NOCTTY) = 3 [pid 30494] openat(AT_FDCWD, "b.h", O_RDONLY|O_NOCTTY) = 3 If it was necessary to open that file, then it's a dependency. > Really #pragma once should just emit a warning just like #import does ... I hear you, :-)
