[libcxx-commits] [PATCH] D132081: [libc++] Remove __deque_base

[Nikolas Klauser via Phabricator via libcxx-commits]

philnik added a comment.

In D132081#3772577 <https://reviews.llvm.org/D132081#3772577>, @brooksmoses wrote:

> I'm seeing new compilation errors from the moved allocator `static_assert` in this patch.
>
> Reduced test case:
>
>   #include <deque>
>   #include <memory>
>   BaseContainerTtemplate <typename T> struct CustomAllocator : public std::allocator<T> {};
>   void foo() {std::deque<int, CustomAllocator<int>> bar;}
>
> Error:
>
>   include/c++/v1/deque:974:3: error: static assertion failed due to requirement 'is_same<CustomAllocator<int>, std::allocator<int>>::value': rebinding an allocator to value_type should result in the original allocator
>     static_assert(is_same<allocator_type, typename __rebind_alloc_helper<__alloc_traits, value_type>::type>::value,
>     ^             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>   test.cc:4:51: note: in instantiation of template class 'std::deque<int, CustomAllocator<int>>' requested here
>   void foo() {std::deque<int, CustomAllocator<int>> bar;}
>                                                     ^
>
> Could you please investigate?

The `static_assert` wasn't moved, it was added. As the error message says, rebinding an allocator to the same type has to result in the same allocator. You have to add something like

  template <class U>
  struct rebind {
      using other = allocator<U>;
  };

to your allocator pre-C++20.


Repository:
  rG LLVM Github Monorepo

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