[Bug c/87345] The compiler of the old version (for example: 4.9.3 version or 6.3.0 version) can stop the infinite cross-border loop, but the new version does not work.

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87345

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

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

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
>void *strlwr(char *str)
> {
...
> //return NULL;
> }
This is the issue and not anything else.
In C++ (unlike C), falling through to return where there is a return type is
undefined code at that point.
(In C, it is undefined if the return value was used).