[Bug middle-end/95276] [10/11 Regression] Amusing stringpop-overflow message building libgfortran

[msebor at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95276

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |INVALID

--- Comment #13 from Martin Sebor <msebor at gcc dot gnu.org> ---
The latest trunk outputs the same warning with a better note (the offset is
correct).  As discussed in comment #7 the warning for the small test case is
correct: the loop overflows the small buffer.  It iterates at least three
times, writing two bytes into the four byte destination in each iteration, for
a total of six bytes.  I don't see a bug here so I'm resolving it as invalid. 
If the test case below isn't representative of the fortran code please submit
one that is.

$ cat pr95276.c && gcc -O2 -S -Wall pr95276.c
char a[4];

void f (char *s, int n)
{
  if (n <= 2)
    return;

  char *d = a;

  for (int i = 0; i < n; i++)
    {
      extern volatile unsigned char h, l;

      *d++ = s[h];
      *d++ = s[l];
    }

  *d = '\0';
}
pr95276.c: In function ‘f’:
pr95276.c:18:6: warning: writing 1 byte into a region of size 0
[-Wstringop-overflow=]
   18 |   *d = '\0';
      |   ~~~^~~~~~
pr95276.c:1:6: note: at offset 6 into destination object ‘a’ of size 4
    1 | char a[4];
      |      ^