[Bug tree-optimization/94021] -Wformat-truncation false positive due to excessive integer range

["ishikawa at yk dot rim.or.jp" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94021

--- Comment #10 from ishikawa,chiaki <ishikawa at yk dot rim.or.jp> ---
It would be great if the problem is fixed in later versions.
I observe the error with gcc-12 on my computer yet.

*BUT* compiling with -O instead of -O2 succeeds !?

gcc-12 version.

gcc-12 (Debian 12.2.0-14) 12.2.0
Copyright (C) 2022 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

No error with -O !?

ishikawa@ip030:/NREF-COMM-CENTRAL/mozilla$ gcc-12 -c -O -Wall /tmp/pr94021.c

Error with -O2 as before.

ishikawa@ip030:/NREF-COMM-CENTRAL/mozilla$ gcc-12 -c -O2 -Wall /tmp/pr94021.c
/tmp/pr94021.c: In function ‘format_utc_offset’:
/tmp/pr94021.c:14:45: warning: ‘%02i’ directive output may be truncated writing
2 bytes into a region of size between 1 and 5 [-Wformat-truncation=]
   14 |     __builtin_snprintf (a, sizeof a, "%s%02i%02i", "+", h, m);
      |                                             ^~~~
/tmp/pr94021.c:14:38: note: directive argument in the range [0, 59]
   14 |     __builtin_snprintf (a, sizeof a, "%s%02i%02i", "+", h, m);
      |                                      ^~~~~~~~~~~~
/tmp/pr94021.c:14:5: note: ‘__builtin_snprintf’ output between 6 and 10 bytes
into a destination of size 8
   14 |     __builtin_snprintf (a, sizeof a, "%s%02i%02i", "+", h, m);
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
ishikawa@ip030:/NREF-COMM-CENTRAL/mozilla$