http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57201
Bug #: 57201 Summary: Using --save-temps affects whether warning is printed Classification: Unclassified Product: gcc Version: 4.8.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c AssignedTo: unassig...@gcc.gnu.org ReportedBy: i...@airs.com Consider this C file: #include <stdio.h> void f(void) { stdout; } When I compile it on my Ubuntu Precise system with GCC 4.8 branch with the -Wall option, I get no error. When I compile it with -Wall --save-temps, I get this: foo.c: In function âfâ: foo.c:5:3: warning: statement with no effect [-Wunused-value] stdout; ^ This appears to happen because <stdio.h> on my system has this line: #define stdout stdout When not using --save-temps, something about this is causing linemap_location_in_system_header_p to return true for "stdout" on line 5.