https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113664
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
-fno-strict-overflow turns on -fwrapv-pointer which allows pointers to wrap
which means if s was non-null, then `s+1` can be still a null pointer ...
And then we go and prop null into dot and s is equal to null at that point. and
then we still generate the code for `*s++ = '.';` in
```
if (s == dot) {
*s++ = '.';
}
```
But it is `*NULL = '.';` due to that.
The warning is very sensitive to the ability to optimization away null pointer
checks in this case. Really `fno-strict-overflow` is normally to workaround
some "undefinedness" in the code and the code should be improved to be fixed.
Using -fwrapv instead also helps because now only signed integer overflows and
not also pointers ...
