Implement the first part of N4258 - allocator_traits<X>::is_always_equal. Also fixes PR#23723
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@238848 91177308-0d34-0410-b5e6-96231b3b80d8
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@@ -0,0 +1,48 @@
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//===----------------------------------------------------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is dual licensed under the MIT and the University of Illinois Open
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// Source Licenses. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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// <memory>
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// template <class Alloc>
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// struct allocator_traits
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// {
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// typedef Alloc::is_always_equal
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// | is_empty is_always_equal;
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// ...
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// };
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#include <memory>
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#include <type_traits>
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template <class T>
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struct A
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{
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typedef T value_type;
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typedef std::true_type is_always_equal;
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};
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template <class T>
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struct B
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{
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typedef T value_type;
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};
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template <class T>
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struct C
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{
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typedef T value_type;
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int not_empty_; // some random member variable
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};
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int main()
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{
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static_assert((std::is_same<std::allocator_traits<A<char> >::is_always_equal, std::true_type>::value), "");
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static_assert((std::is_same<std::allocator_traits<B<char> >::is_always_equal, std::true_type>::value), "");
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static_assert((std::is_same<std::allocator_traits<C<char> >::is_always_equal, std::false_type>::value), "");
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}
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