[Bug c/128554] Bogus -Wshift-count-negative warning for __builtin_stdc_bit_floor with a zero-valued const variable

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=128554

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2026-11-08
             Status|UNCONFIRMED                 |NEW
     Ever confirmed|0                           |1

--- Comment #1 from Drea Pinski <pinskia at gcc dot gnu.org> ---
Confirmed.  There is code to handle the warning explictly for a literal 0 but
not for constanted folded one:

```
            /* For __builtin_stdc_bit_ceil (0U) or __builtin_stdc_bit_ceil (1U)
               or __builtin_stdc_bit_floor (0U) avoid bogus -Wshift-count-*
               warnings.  The LSHIFT_EXPR is in dead code in that case.  */

```