On 10/6/25 19:03, Andrew Pinski wrote:
On Mon, Oct 6, 2025 at 5:58 PM Sam James <[email protected]> wrote:CCP interacts poorly with -Wuninitialized in some cases by assuming a value which stops us warning about it (false negatives). Inform users about this infamous interaction. gcc/ChangeLog: PR tree-optimization/18501 * doc/invoke.texi (-Wuninitialized): Mention interaction with CCP. --- We give some 'more effective' notes like this for -ftree-vrp. What do you think?Not a fan at all of the "more effective" here. Since unlike the other effective notes which are about turning on optimizations, this is about turning them off. Maybe the following is better: ``` -Wmaybe-uninitialized is known not to warn in many situations (false negatives) due to some optimizations (like cpp, -ftree-ccp). ```
Yeah, my initial reaction was that "more effective" didn't really explain what the problem was. I think it would be better to phrase this more directly in the active voice, something like
Some optimizations interfere with @option{-Wmaybe-uninitialized} and may cause false negatives. In particular, disabling the conditional constant propagation pass with @option{-fno-tree-ccp} gives more accurate diagnostics.
?? -Sandra
