> On Nov 2, 2016, at 16:20, Richard Smith <rich...@metafoo.co.uk> wrote: > > On Wed, Nov 2, 2016 at 3:51 PM, Jordan Rose via cfe-commits > <cfe-commits@lists.llvm.org <mailto:cfe-commits@lists.llvm.org>> wrote: > >> On Nov 2, 2016, at 15:48, Richard Smith <rich...@metafoo.co.uk >> <mailto:rich...@metafoo.co.uk>> wrote: >> >> On Wed, Nov 2, 2016 at 2:34 PM, Jordan Rose via cfe-commits >> <cfe-commits@lists.llvm.org <mailto:cfe-commits@lists.llvm.org>> wrote: >> >>> On Nov 2, 2016, at 14:31, Richard Smith <rich...@metafoo.co.uk >>> <mailto:rich...@metafoo.co.uk>> wrote: >>> >>> On 2 Nov 2016 1:53 pm, "Jordan Rose via cfe-commits" >>> <cfe-commits@lists.llvm.org <mailto:cfe-commits@lists.llvm.org>> wrote: >>> Author: jrose >>> Date: Wed Nov 2 15:44:07 2016 >>> New Revision: 285856 >>> >>> URL: http://llvm.org/viewvc/llvm-project?rev=285856&view=rev >>> <http://llvm.org/viewvc/llvm-project?rev=285856&view=rev> >>> Log: >>> Don't require nullability on template parameters in typedefs. >>> >>> Previously the following code would warn on the use of "T": >>> >>> template <typename T> >>> struct X { >>> typedef T *type; >>> }; >>> >>> ...because nullability is /allowed/ on template parameters (because >>> they could be pointers). (Actually putting nullability on this use of >>> 'T' will of course break if the argument is a non-pointer type.) >>> >>> This doesn't make any sense to me. Why would T need to be a pointer type >>> for a nullability qualifier to be valid on a T*? >> >> Sorry, this is referring to the following change to the example: >> >> template <typename T> >> struct X { >> typedef T _Nullable *type; >> }; >> >> This is legal, but of course `X<int>` then produces an error. So we want to >> accept nullability in this position (in case T is implicitly required to be >> a pointer type by the definition of X) but not warn when it’s missing (in >> case it isn’t). >> >> Oh, I see. Your testcase is very confusing, though, since it wraps the >> problematic use of T in a completely-unrelated pointer type. The actual >> problem being fixed is much more obvious in a case like this: >> >> int *_Nullable p; >> template<typename T> struct X { >> T t; // warns without your fix >> }; >> >> It'd be easier on future readers of this code to use the more obvious test >> case here. > > Ah, that case doesn’t actually trigger the issue, because a typedef doesn’t > require nullability on its outermost pointer type. (It’s assumed that the use > site may need to make some uses of the typedef nullable and some > non-nullable.) > > The testcase I gave above definitely produces a bogus warning before your > patch. I've not actually checked whether the patch fixes it, though. >
Oops, sorry, I misread it thinking it still said ‘typedef’. Yes, that does warn, and no, this patch does not fix it. Jordan
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