[Bug c/64175] New: #pragma GCC diagnostic pop doesn't re-disable -Wnested-externs

[plokinom at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64175

            Bug ID: 64175
           Summary: #pragma GCC diagnostic pop doesn't re-disable
                    -Wnested-externs
           Product: gcc
           Version: 4.9.2
            Status: UNCONFIRMED
          Severity: minor
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: plokinom at gmail dot com

$ cat foo.c
#pragma GCC diagnostic warning "-Wnested-externs"
#pragma GCC diagnostic pop
static void bar(void) { extern int main(void); }
int main(void) { return 0; }

$ gcc foo.c
foo.c: In function ‘bar’:
foo.c:3:1: warning: nested extern declaration of ‘main’ [-Wnested-externs]
 static void bar(void) { extern int main(void); }
 ^

I think this is a bug because according to the documentation "If a 'pop' has no
matching 'push', the command-line options are restored" and there is no
-Wnested-externs on the command line, so gcc shouldn't warn.