[Bug debug/126801] [13/14/15/16/17 Regression] fvar-tracking-uninit is on by accident via r12-4397

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126801

--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
For minimal fix I'd go with
2026-08-19  Jakub Jelinek  <[email protected]>

        PR debug/126801
        * opts.cc (finish_options): Don't set flag_var_tracking_uninit to
        flag_var_tracking by default.  Instead, set flag_var_tracking to
        flag_var_tracking_uninit if the latter was explicitly set.
        * config/darwin.cc (darwin_override_options): Only set
        flag_var_tracking_uninit if it wasn't explicitly set and set it to
        1 rather than flag_var_tracking.  Formatting fix.

--- gcc/opts.cc.jj      2026-08-18 08:47:22.044793076 +0200
+++ gcc/opts.cc 2026-08-19 12:28:11.107209028 +0200
@@ -1499,9 +1499,8 @@ finish_options (struct gcc_options *opts
       opts->x_flag_var_tracking_assignments = 0;
     }

-  /* One could use EnabledBy, but it would lead to a circular dependency.  */
-  if (!opts_set->x_flag_var_tracking_uninit)
-    opts->x_flag_var_tracking_uninit = opts->x_flag_var_tracking;
+  if (opts_set->x_flag_var_tracking_uninit &&
opts->x_flag_var_tracking_uninit)
+    opts->x_flag_var_tracking = 1;

   if (!opts_set->x_flag_var_tracking_assignments)
     opts->x_flag_var_tracking_assignments
--- gcc/config/darwin.cc.jj     2026-08-17 10:00:21.681856778 +0200
+++ gcc/config/darwin.cc        2026-08-19 12:24:08.235382015 +0200
@@ -3576,12 +3576,13 @@ darwin_override_options (void)
       flag_asynchronous_unwind_tables = 0;
     }

-  if (flag_var_tracking_uninit == 0
+  if (!OPTION_SET_P (flag_var_tracking_uninit)
+      && flag_var_tracking_uninit == 0
       && generating_for_darwin_version >= 9
       && (flag_gtoggle ? (debug_info_level == DINFO_LEVEL_NONE)
-      : (debug_info_level >= DINFO_LEVEL_NORMAL))
+         : (debug_info_level >= DINFO_LEVEL_NORMAL))
       && dwarf_debuginfo_p ())
-    flag_var_tracking_uninit = flag_var_tracking;
+    flag_var_tracking_uninit = 1;

   if (OPTION_SET_P (flag_pie) && flag_pie)
     {

This undoes some of the mistakes made in r12-4397:
1) gcc before that change did
  /* If the user specifically requested variable tracking with tagging
     uninitialized variables, we need to turn on variable tracking.
     (We already determined above that variable tracking is feasible.)  */
  if (flag_var_tracking_uninit == 1)            
    flag_var_tracking = 1;
   which disappeared; i.e. -fvar-tracking-uninit implied -fvar-tracking
2) it removes the bogus assumption that flag_var_tracking_uninit used to be
   AUTODETECT_VALUE by default, it only did in the darwin case
3) fixes the darwin case, so that if one uses explicit -fno-var-tracking-uninit
   then it is honored rather than overridden