https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90844
Martin Sebor <msebor at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |msebor at gcc dot gnu.org
Summary|Another case of missing use |missing
|of uninitialized variable |-Wmaybe-uninitialized with
|warning (inlining, CCP) |-flto and optimization
Last reconfirmed|2019-06-12 00:00:00 |2021-4-15
Known to fail| |10.2.0, 11.0, 8.3.0, 9.3.0
--- Comment #3 from Martin Sebor <msebor at gcc dot gnu.org> ---
The late uninit pass doesn't run with -flto; all that runs is the early
uninitialized pass and it disables the "conditional" -Wmaybe-uninitialized when
optimization is enabled:
static unsigned int
execute_early_warn_uninitialized (void)
{
/* Currently, this pass runs always but
execute_late_warn_uninitialized only runs with optimization. With
optimization we want to warn about possible uninitialized as late
as possible, thus don't do it here. However, without
optimization we need to warn here about "may be uninitialized". */
calculate_dominance_info (CDI_POST_DOMINATORS);
warn_uninitialized_vars (/*warn_maybe_uninitialized=*/!optimize);
^^^^^^^^^
Changing that like so lets the warning do its thing even with -flto:
@@ -3086,7 +3079,8 @@ execute_early_warn_uninitialized (void)
optimization we need to warn here about "may be uninitialized". */
calculate_dominance_info (CDI_POST_DOMINATORS);
- warn_uninitialized_vars (/*warn_maybe_uninitialized=*/!optimize);
+ bool wmaybe_uninit = !optimize || flag_lto;
+ warn_uninitialized_vars (wmaybe_uninit);
/* Post-dominator information cannot be reliably updated. Free it
after the use. */
