[Bug middle-end/106427] -Wuse-after-free=3 false alarm about int (not pointer) variable

[simon at josefsson dot org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106427

Simon Josefsson <simon at josefsson dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |simon at josefsson dot org

--- Comment #1 from Simon Josefsson <simon at josefsson dot org> ---
I ran into this problem too, here is a simple reproducer:

$ gcc -Werror -Wuse-after-free=3 -g -O2 -o foo foo.c
foo.c: In function 'main':
foo.c:18:6: error: pointer may be used after 'free' [-Werror=use-after-free]
   18 |   if (strstr (in, "FOO"))
      |      ^
foo.c:21:3: note: call to 'free' here
   21 |   free (in);
      |   ^~~~~~~~~
cc1: all warnings being treated as errors

#include <string.h>
#include <stdlib.h>

extern int readln (char **out);

int
main (void)
{
  char *in = NULL;
  int i = 0;

  if (!readln (&in))
    return 0;

  if (in == NULL)
    return 0;

  if (strstr (in, "FOO"))
    i = 1;

  free (in);
  in = NULL;

  if (!readln (&in))
    return 0;

  if (in == NULL)
    return 0;

  free (in);

  return i;
}