aaron.ballman added inline comments.
================ Comment at: include/clang/Basic/DiagnosticGroups.td:108-109 def DeleteNonVirtualDtor : DiagGroup<"delete-non-virtual-dtor">; +def DeleteAbstractNonVirtualDtor : DiagGroup<"delete-abstract-non-virtual-dtor", + [DeleteNonVirtualDtor]>; def AbstractFinalClass : DiagGroup<"abstract-final-class">; ---------------- rsmith wrote: > aaron.ballman wrote: > > rsmith wrote: > > > This is backwards: this says that `-Wdelete-abstract-non-virtual-dtor` > > > also controls `-Wdelete-non-virtual-dtor`. You presumably want the > > > opposite relationship, so that `-Wdelete-non-virtual-dtor` controls both > > > warnings and `-Wdelete-abstract-non-virtual-dtor` only controls the > > > "abstract" warning. > > I took this to be the correct order because disabling the abstract case is > > more dangerous than disabling the non-abstract case (if you disable the > > abstract one, you're saying "I don't care how bad it gets, don't tell me > > about it."). > That seems reasonable as a strategy, but the end result doesn't seem to make > much sense: `-Wdelete-abstract-non-virtual-dtor` enables, and > `-Wno-delete-abstract-non-virtual-dtor` disables, warnings that have nothing > to do with deleting an abstract class with a non-virtual destructor, and > `-Wno-delete-non-virtual-dtor` fails to silence warnings about deleting an > object of a class type with a non-virtual destructor. It's also > backwards-incompatible, because the meaning of the existing `-W` flag has > been changed. > > One way to fix this would be to rename the groups: > > * `delete-abstract-non-virtual-dtor` -> `delete-non-virtual-dtor` > * `delete-non-virtual-dtor` -> `delete-nonabstract-non-virtual-dtor` (yuck) > > (Or we could keep the existing `delete-abstract-non-virtual-dtor`, add > `delete-nonabstract-non-virtual-dtor`, and make `delete-non-virtual-dtor` be > a group that contains those other two groups and has no diagnostics of its > own.) > > Instead / as well, we could address the false positives more directly: we > could only warn if the class in question *introduces* a virtual function > (suggesting that it's intended to be used as a base class), rather than > warning if the class merely *has* virtual functions (if it overrides virtual > functions and doesn't introduce any, there's a good chance it's a leaf > class). `-Wdelete-non-virtual-dtor` was supposed to be the "few/no false > positives" version of `-Wnon-virtual-dtor` (which is really really just a > stylistic warning), and if we can improve it so that people don't want to > turn it off, that'd seem better. > That seems reasonable as a strategy, but the end result doesn't seem to make > much sense: -Wdelete-abstract-non-virtual-dtor enables, and > -Wno-delete-abstract-non-virtual-dtor disables, warnings that have nothing to > do with deleting an abstract class with a non-virtual destructor, and > -Wno-delete-non-virtual-dtor fails to silence warnings about deleting an > object of a class type with a non-virtual destructor. It's also > backwards-incompatible, because the meaning of the existing -W flag has been > changed. Ah, those are all good points! > (Or we could keep the existing delete-abstract-non-virtual-dtor, add > delete-nonabstract-non-virtual-dtor, and make delete-non-virtual-dtor be a > group that contains those other two groups and has no diagnostics of its own.) I have a slight preference for this approach; it feels a bit more natural to me. However, do we want to spell it `delete-nonabstract-non-virtual-dtor` or `delete-non-abstract-non-virtual-dtor` or `delete-nonabstract-nonvirtual-dtor`? My preference is for anything but the first spelling. ;-) > Instead / as well, we could address the false positives more directly: Yes, improving the fp rate that way would be a great change to make. That said, I would view it as "as well" rather than "instead" because these two diagnostic scenarios seem reasonably separable. Repository: rC Clang CHANGES SINCE LAST ACTION https://reviews.llvm.org/D56405/new/ https://reviews.llvm.org/D56405 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
