[Bug middle-end/82101] missed warning for uninitialized value on the loop entry edge

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82101

Martin Sebor <msebor at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|FIXED                       |---
      Known to fail|                            |10.2.0, 11.0, 7.3.0, 8.3.0,
                   |                            |9.2.0
   Last reconfirmed|2017-09-05 00:00:00         |2021-4-2
             Status|RESOLVED                    |NEW

--- Comment #4 from Martin Sebor <msebor at gcc dot gnu.org> ---
Let me take that back.  The complaint is about the missing warning for the
variable in the loop, not the one outside it, and presumably with -O1 or above.
 That's not quite clear from the description.

Here's a test case for the problem.  It's never been diagnosed:

$ cat pr82101.C && gcc -O1  -S -Wall pr82101.C
void f (int);

void g (void)
{
  for (int i = 0; i < 10; i++)
    {
      int t = t;   // -Wuninitialized  
      f (t);
    }
}

void h (void)
{
  for (int i = 0; i < 10; i++)
    {
      int t = t;   // missing warning 
    }
}

pr82101.C: In function ‘void g()’:
pr82101.C:8:9: warning: ‘t’ is used uninitialized [-Wuninitialized]
    8 |       f (t);
      |       ~~^~~
pr82101.C:7:11: note: ‘t’ was declared here
    7 |       int t = t;   // -Wuninitialized
      |           ^