[Bug c/99340] New: [10/11 Regression] -Werror=maybe-uninitialized warning with -fPIE, but not -fPIC

[doko at debian dot org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99340

            Bug ID: 99340
           Summary: [10/11 Regression] -Werror=maybe-uninitialized warning
                    with -fPIE, but not -fPIC
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: doko at debian dot org
  Target Milestone: ---

seen building the gsequencer package.
the warning was not emitted with gcc-10 branch 20210110, but is emitted with
20210228, also emitted with trunk 20210220.

$ cat ags_midi_buffer_util.i
long ags_midi_buffer_util_seek_message_delta_time;
int ags_midi_buffer_util_seek_message_i;
int ags_midi_buffer_util_get_varlength() { return 0; }
char ags_midi_buffer_util_seek_message() {
  long current_delta_time;
  for (; ags_midi_buffer_util_seek_message_i;
       ags_midi_buffer_util_seek_message_i++) {
    ags_midi_buffer_util_get_varlength(&current_delta_time);
    ags_midi_buffer_util_seek_message_delta_time = current_delta_time;
  }
  return 0;
}

$ gcc -std=gnu99 -Wall -Werror=maybe-uninitialized -fstack-protector-strong
-fPIE -O1 -c ags_midi_buffer_util.i
ags_midi_buffer_util.i: In function 'ags_midi_buffer_util_seek_message':
ags_midi_buffer_util.i:5:8: error: 'current_delta_time' may be used
uninitialized in this function [-Werror=maybe-uninitialized]
    5 |   long current_delta_time;
      |        ^~~~~~~~~~~~~~~~~~
cc1: some warnings being treated as errors