On Mon, 3 Jun 2024 at 15:49, Daniel P. Berrangé <berra...@redhat.com> wrote: > We can't rely on the sanitizers to catch all cases where we're casting > functions, as we don't have good enough code coverage in tests to > identify all places that way. > > Unless there's a warning flag we can use to get diagnosis of this > problem at compile time and then fix all reported issues, I won't have > any confidence in our ability to remove > -fsanitize-cfi-icall-generalize-pointers > for CFI.
You might think that -Wcast-function-type would detect them at compile time, but that has two loopholes: 1. void(*) (void) matches everything 2. any parameter of pointer type matches any other pointer type It seems to me rather inconsistent that the sanitizers do not match up with the warning semantics here. I think I would vote for raising that with the compiler folks -- either the sanitizer should be made looser so it matches the -Wcast-function-type semantics, or else a new tighter warning option that matches the sanitizer should be provided. Ideally both, I think. But it's definitely silly to have a runtime check that flags up things that the compiler perfectly well could detect at compile time but is choosing not to. thanks -- PMM
