[Bug tree-optimization/104415] New: uninit diagnostic improvement at -O0

[Bug tree-optimization/104415] New: uninit diagnostic improvement at -O0

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104415

            Bug ID: 104415
           Summary: uninit diagnostic improvement at -O0
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: rguenth at gcc dot gnu.org
  Target Milestone: ---

For

int foo ()
{
  int cond = 1;
  int tem;
  return cond ? tem : 0;
}

we emit

t.c: In function 'foo':
t.c:5:21: warning: 'tem' may be used uninitialized [-Wmaybe-uninitialized]
    5 |   return cond ? tem : 0;
      |          ~~~~~~~~~~~^~~
t.c:4:7: note: 'tem' was declared here
    4 |   int tem;
      |       ^~~

when not optimizing but

t.c: In function 'foo':
t.c:5:21: warning: 'tem' is used uninitialized [-Wuninitialized]
    5 |   return cond ? tem : 0;
      |          ~~~~~~~~~~~^~~
t.c:4:7: note: 'tem' was declared here
    4 |   int tem;
      |       ^~~

when optimizing.  Even when not optimizing we could figure out the condition
is constant and emit the "is used uninitialized" variant.

[Bug tree-optimization/104415] uninit diagnostic improvement at -O0

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104415

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Depends on|                            |104373

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
PR104373 mentions how this can be improved.


Referenced Bugs:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104373
[Bug 104373] [12 regression] bogus -Wmaybe-uninitialized warning with array new

[Bug tree-optimization/104415] uninit diagnostic improvement at -O0

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104415

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2022-02-07
             Status|UNCONFIRMED                 |NEW
     Ever confirmed|0                           |1

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Confirmed.

[Bug tree-optimization/104415] uninit diagnostic improvement at -O0

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104415
Bug 104415 depends on bug 104373, which changed state.

Bug 104373 Summary: [12 regression] bogus -Wmaybe-uninitialized warning with array new
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104373

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|---                         |FIXED