opts: Use OPTION_SET_P instead of magic value 2 for -fshort-enums default [PR118011]

The magic values for default (usually -1 or sometimes 2) for some options
are from times we haven't global_options_set, I think we should eventually
get rid of all of those.

The PR is about gcc -Q --help=optimizers reporting -fshort-enums as
[enabled] when it is disabled.
For this the following patch is just partial fix; with explicit
gcc -Q --help=optimizers -fshort-enums
or
gcc -Q --help=optimizers -fno-short-enums
it already worked correctly before, with this patch it will report
even with just
gcc -Q --help=optimizers
correct value on most targets, except 32-bit arm with some options or
defaults, so I think it is a step in the right direction.

But, as I wrote in the PR, process_options isn't done before --help=
and even shouldn't be in its current form where it warns on some option
combinations or errors or emits sorry on others, so I think ideally
process_options should have some bool argument whether it is done for
--help= purposes or not, if yes, not emit warnings and just adjust the
options, otherwise do what it currently does.

2024-12-14  Jakub Jelinek  <jakub@redhat.com>

	PR c/118011
gcc/
	* opts.cc (init_options_struct): Don't set opts->x_flag_short_enums to
	2.
	* toplev.cc (process_options): Test !OPTION_SET_P (flag_short_enums)
	rather than flag_short_enums == 2.
gcc/ada/
	* gcc-interface/misc.cc (gnat_post_options): Test
	!OPTION_SET_P (flag_short_enums) rather than flag_short_enums == 2.

3 files changed, 2 insertions, 5 deletions

diff --git a/gcc/ada/gcc-interface/misc.cc b/gcc/ada/gcc-interface/misc.cc
index c7c735e5..d3f8ffa 100644
--- a/gcc/ada/gcc-interface/misc.cc
+++ b/gcc/ada/gcc-interface/misc.cc
@@ -283,7 +283,7 @@ gnat_post_options (const char **pfilename ATTRIBUTE_UNUSED)
   /* Unfortunately the post_options hook is called before the value of
      flag_short_enums is autodetected, if need be.  Mimic the process
      for our private flag_short_enums.  */
-  if (flag_short_enums == 2)
+  if (!OPTION_SET_P (flag_short_enums))
     flag_short_enums = targetm.default_short_enums ();
 
   return false;
diff --git a/gcc/opts.cc b/gcc/opts.cc
index 9909d4a..fa64bb7 100644
--- a/gcc/opts.cc
+++ b/gcc/opts.cc
@@ -444,9 +444,6 @@ init_options_struct (struct gcc_options *opts, struct gcc_options *opts_set)
 
   /* Initialize whether `char' is signed.  */
   opts->x_flag_signed_char = DEFAULT_SIGNED_CHAR;
-  /* Set this to a special "uninitialized" value.  The actual default
-     is set after target options have been processed.  */
-  opts->x_flag_short_enums = 2;
 
   /* Initialize target_flags before default_options_optimization
      so the latter can modify it.  */
diff --git a/gcc/toplev.cc b/gcc/toplev.cc
index 370d7f3..5f19ebb 100644
--- a/gcc/toplev.cc
+++ b/gcc/toplev.cc
@@ -1300,7 +1300,7 @@ process_options ()
       flag_section_anchors = 0;
     }
 
-  if (flag_short_enums == 2)
+  if (!OPTION_SET_P (flag_short_enums))
     flag_short_enums = targetm.default_short_enums ();
 
   /* Set aux_base_name if not already set.  */