https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100680
--- Comment #3 from jbeulich at suse dot com --- (In reply to Martin Sebor from comment #2) > The warning is by design: it considers a constant non-null pointer value a > likely result of (invalid) arithmetic on a null pointer, as in the example > in pr99578 comment #1. If the warning is by design, there ought to be a way to avoid these specific instances without disabling the warning altogether. I'm also observing such bogus warnings in cases other than pointer derivation from literal numbers, possibly along the lines of what Andi has said in that other bug in comment 12. For Xen I've submitted a patch to work around the issue without disabling the warning, but it's not really pretty: https://lists.xen.org/archives/html/xen-devel/2021-05/msg01058.html I also consider Richard's comment 7 in that other bug as quite relevant. The compiler _guessing_ that offsetting from a NULL pointer is an actual issue conflicts with people intentionally doing so. Warnings based on heuristics should imo always be separately controllable, such that they can - if the heuristics prove to be wrong - be turned off, without affecting other, non-heuristic warnings. This is even more relevant for all those projects (like the Xen hypervisor) building with -Werror, resulting in false positive warnings breaking the build.
