[libcxx-commits] [PATCH] D133638: [libc++] static_assert that rebinding the allocator works as expected

[Bogdan Graur via Phabricator via libcxx-commits]

bgraur added a comment.

In D133638#3850477 <https://reviews.llvm.org/D133638#3850477>, @philnik wrote:

> @rupprecht I don't think there is a bug here. You allocator isn't conforming. The difference between your example and the standard example is that the standard example is a template, which can be rebound by default (see https://eel.is/c++draft/allocator.requirements#general-18). This is actually one of the bugs this patch is trying to catch.

I have a followup question regarding this: the statement you linked (https://eel.is/c++draft/allocator.requirements#general-18) says that for `SomeAllocator<T, Args>` if "`Allocator` does not supply a rebind member template, the standard allocator_­traits template uses SomeAllocator<U, Args> in place of Allocator​::​rebind<U>​::​other by default."

With this change the statement stands for a `template <class T, class Y> class FooAllocator {.. }` (https://godbolt.org/z/4PjeedeP4) and doesn't for a `template <class T, int X> class FooAllocator {.. }` (https://godbolt.org/z/j9sxo65vc).
In the latter case we still look for the `rebind<_Up>::other` member template.

Is that intended?


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https://reviews.llvm.org/D133638