[Bug c/71852] add warning for conditions that can never be true

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71852

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
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                 CC|                            |jakub at gcc dot gnu.org

--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
We do have a simple bitmask propagation pass - ccp.
The question is if it isn't too late for such warning, as in if the preceeding
optimizations don't change the code enough (even for ccp1) that the warning
would have too many false positives.