https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87038
--- Comment #21 from Harald van Dijk <harald at gigawatt dot nl> --- (In reply to Segher Boessenkool from comment #20) > That is still not what I said, so don't pretend I did please. > > Those are also not false positives: in all these cases, the program does > in fact skip some initialisation. "Pretend"? When you misrepresented my words, I did not accuse you of any type of deception, I assumed it was simply a misunderstanding and responded accordingly. I'd appreciate the same treatment from you. You made an ambiguous comment which I did not recognise as ambiguous at the time. You wrote: > -Wall please, unless there are frequent false positives. [...] "False positive" can be interpreted in two ways. It can be read as a false positive wrt -Wjump-misses-init, meaning a warning where no initialisation is jumped over. It turns out this is what you meant. It can also be read as I did, which is a false positive wrt -Wall, which is documented as: > This enables all the warnings about constructions that some users > consider questionable, and that are easy to avoid (or modify to > prevent the warning), even in conjunction with macros. [...] A false positive here would mean that the warning is either about a construct that users do not consider questionable, or that is not easy to avoid. I was responding based on the assumption that this is what you meant. Initialisation is commonly jumped over in large bodies of C code, which is a good indication that it is not largely considered questionable, and of the cases I'd found, although all can be worked around to suppress the warning, quite a lot of them would get a lot uglier. It did not even scan to me that you might be saying that the only reason you'd not propose -Wjump-misses-init be included in -Wall is if -Wjump-misses-init doesn't do what it's supposed to. > But, it seems -Wjump-misses-init is not what you want; you do not want a > warning for jumping over initialisers, it warns for a lot of harmless code. > What you want is a warning that only warns if the var is (potentially) used > without initialisation? Yes, at least for -Wall. Since -Wjump-misses-init triggers too often for commonly used C patterns, I do not think it is appropriate to include it in -Wall. At the same time, for the originally reported code, it does seem like *some* warning at -Wall would be appropriate. A warning about the use of the potentially-uninitialised variable, as clang does, seems sensible to me.
