Hi Siddhesh, On 2/17/23 04:48, Siddhesh Poyarekar wrote: > On 2023-02-16 10:15, David Malcolm via Gcc wrote: >> I'm not convinced that it's useful to the end-user to warn about the >> "use of q itself" case. > > FWIW, -Wuse-after-free=3 already should do this:
Thanks! It works. I would have expected such a warning to be included in -Wextra. Does it have any false positives (or maybe too many false negatives?) that make it unsuitable for -Wextra? > > At level 3, the warning also diagnoses uses of indeterminate pointers in > equality expressions. All uses of indeterminate pointers are undefined > but equality tests sometimes appear after > calls to "realloc" as an attempt to determine whether the call resulted > in relocating the object to a different address. They are diagnosed at > a separate level to aid legacy code gradually > transition to safe alternatives. For example, the equality test in the > function below is diagnosed at this level: > > Jakub and I had discussed this in the context of _FORTIFY_SOURCE=3 > (which is anal about this and can break things) and we got pr#105217, > but that is also a best-effort thing, not really a guarantee. > > IMO the analyzer should go that extra mile and warn for the use of q > itself and maybe deprecate -Wuse-after-free=3 in its favour. > > Sid Cheers, Alex -- <http://www.alejandro-colomar.es/> GPG key fingerprint: A9348594CE31283A826FBDD8D57633D441E25BB5
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