mboehme added a comment. In https://reviews.llvm.org/D49910#1187809, @aaron.ballman wrote:
> In https://reviews.llvm.org/D49910#1187492, @mboehme wrote: > > > In https://reviews.llvm.org/D49910#1187455, @aaron.ballman wrote: > > > > > Are you going to propose adding this attribute to libc++, or is this > > > expected to only work with UDTs? > > > > > > I don't have any experience contributing to libc++, but I think this would > > make sense. > > > > The check currently hard-codes various member functions of classes in the > > "std" namespace that do reinitializations; I'm not sure though if those can > > be removed after the attribute has been added to libc++. We'd would also > > presumably have to add the attribute to libstdc++ -- does it accept > > Clang-only attributes? And what is the story for people using clang-tidy > > with MSVC projects? (I have to admit I'm very hazy on how that works...) > > > I ask the question because it's novel to add an attribute to Clang that's > used only by clang-tidy, and I'm wondering who is expected to use that > attribute to help with this check. Is it expected to be an attribute users > use with their own custom datatypes and it's not needed for standards-based > APIs (because we handle those some other way), or something else? As it > stands, I sort of feel like this is a very heavy approach to solve an edge > case -- is there a lot of evidence for re-using a moved-from object after > reinitializing it? Ah, now I understand what you're getting at. Yes, I see this attribute mainly as something that people would add to their own user-defined types -- typically, containers and smart pointers. I've regularly been getting internal feature requests for this. One typical pattern in which this comes up is the following: MyContainer<T> container; T t; while (GetNextT(&t)) { container.Add(t); if (SomeCondition()) { PassToConsumer(std::move(container)); container.Clear(); } } I.e. you're incrementally adding items to some data structure, and at some point you decide the data structure is now complete, so you hand it off to a consumer and clear it, ready to be filled with the next batch of items. As clang-tidy doesn't understand that the "container.Clear()" reinitializes the container, it complains that the Clear() is a use-after-move. Yes, it's unusual to add an attribute to Clang that is only (at least initially) intended for use by clang-tidy -- but I don't really see how to implement this other than with an attribute. Repository: rCTE Clang Tools Extra https://reviews.llvm.org/D49910 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
