https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108101
Bug ID: 108101
Summary: "#pragma once" causes other files not be included
Product: gcc
Version: 12.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: preprocessor
Assignee: unassigned at gcc dot gnu.org
Reporter: terra at gnome dot org
Target Milestone: ---
# (echo '#pragma once'; echo 'Killroy was here') > a.h
# (echo '#pragma once'; echo 'Killroy was here') > b.h
# (echo '#include "a.h"'; echo '#include "b.h"') > c.c
# gcc -E c.c | grep Killroy
1
# clang -E c.c | grep Killroy
2
According to gcc, Killroy was only there once. Clang is keeping better track
and spots him there twice.
This seems to be version independent: tried 7.5.0 and 12.1.0
