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From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug sanitizer/99945] missing maybe-uninitialized warning when using
 nested function vs SRA
Date: Tue, 11 Jul 2023 19:02:42 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D99945

--- Comment #7 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
This has nothing to do with cleanup functions but just nested functions vs =
SRA.
Take:
```

int foo1 (void);
int foo2 (int);

#ifdef D
#define N
#else
#define N !
#endif

int bar (void)
{
  int i;
  auto void cf (int *t) { foo2 (i); }
  int t;

  t =3D 0;

  if (foo1 ())
    i =3D foo1 ();

  i =3D N foo1 () || i;
  foo2 (i);

  cf(&t);
  return 0;
}
```
Which is the same as the original one without the cleanup attribute (basica=
lly
added the call to cf).

Using `-O2 -Wall  -DD -fno-tree-sra` causes the following warning the be do=
ne:
```
<source>: In function 'bar':
<source>:22:17: warning: 'FRAME.1.i' may be used uninitialized
[-Wmaybe-uninitialized]
   22 |   i =3D N foo1 () || i;
      |         ~~~~~~~~^~~~
<source>:11:5: note: 'FRAME.1' declared here
   11 | int bar (void)
      |     ^~~
```

Without `-fno-tree-sra`, there is no warning because SRA produces:
```
  # SR.4_14 =3D PHI <SR.4_12(D)(5), _9(3)>
  _2 =3D foo1 ();
  _17 =3D _2 | SR.4_14;

```
which should 100% warn but since SR.4 is artifical does not.=