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Add an `__is_inplace_index` metafunction. 

Summary: This is used to constrain `variant`'s converting constructor correctly.

Reviewers: EricWF, mclow.lists

Reviewed By: EricWF, mclow.lists

Differential Revision: https://reviews.llvm.org/D34111

llvm-svn: 305370
This commit is contained in:
Michael Park 2017-06-14 05:51:18 +00:00
parent ba59c2f63b
commit 9cac9ad9d4
3 changed files with 70 additions and 0 deletions
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6
libcxx/include/utility
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@ -930,6 +930,12 @@ template <class _Tp> struct __is_inplace_type_imp<in_place_type_t<_Tp>> : true_t
template <class _Tp>
using __is_inplace_type = __is_inplace_type_imp<__uncvref_t<_Tp>>;
template <class _Tp> struct __is_inplace_index_imp : false_type {};
template <size_t _Idx> struct __is_inplace_index_imp<in_place_index_t<_Idx>> : true_type {};
template <class _Tp>
using __is_inplace_index = __is_inplace_index_imp<__uncvref_t<_Tp>>;
#endif // _LIBCPP_STD_VER > 14
template <class _Arg, class _Result>

32
libcxx/test/libcxx/utilities/utility/__is_inplace_index.pass.cpp Normal file
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@ -0,0 +1,32 @@
//===----------------------------------------------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is dual licensed under the MIT and the University of Illinois Open
// Source Licenses. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
// template <class _Tp> using __is_inplace_index
#include <utility>
struct S {};
int main() {
using I = std::in_place_index_t<0>;
static_assert( std::__is_inplace_index<I>::value, "");
static_assert( std::__is_inplace_index<const I>::value, "");
static_assert( std::__is_inplace_index<const volatile I>::value, "");
static_assert( std::__is_inplace_index<I&>::value, "");
static_assert( std::__is_inplace_index<const I&>::value, "");
static_assert( std::__is_inplace_index<const volatile I&>::value, "");
static_assert( std::__is_inplace_index<I&&>::value, "");
static_assert( std::__is_inplace_index<const I&&>::value, "");
static_assert( std::__is_inplace_index<const volatile I&&>::value, "");
static_assert(!std::__is_inplace_index<std::in_place_type_t<int>>::value, "");
static_assert(!std::__is_inplace_index<std::in_place_t>::value, "");
static_assert(!std::__is_inplace_index<void>::value, "");
static_assert(!std::__is_inplace_index<int>::value, "");
static_assert(!std::__is_inplace_index<S>::value, "");
}

32
libcxx/test/libcxx/utilities/utility/__is_inplace_type.pass.cpp Normal file
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@ -0,0 +1,32 @@
//===----------------------------------------------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is dual licensed under the MIT and the University of Illinois Open
// Source Licenses. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
// template <class _Tp> using __is_inplace_type
#include <utility>
struct S {};
int main() {
using T = std::in_place_type_t<int>;
static_assert( std::__is_inplace_type<T>::value, "");
static_assert( std::__is_inplace_type<const T>::value, "");
static_assert( std::__is_inplace_type<const volatile T>::value, "");
static_assert( std::__is_inplace_type<T&>::value, "");
static_assert( std::__is_inplace_type<const T&>::value, "");
static_assert( std::__is_inplace_type<const volatile T&>::value, "");
static_assert( std::__is_inplace_type<T&&>::value, "");
static_assert( std::__is_inplace_type<const T&&>::value, "");
static_assert( std::__is_inplace_type<const volatile T&&>::value, "");
static_assert(!std::__is_inplace_type<std::in_place_index_t<0>>::value, "");
static_assert(!std::__is_inplace_type<std::in_place_t>::value, "");
static_assert(!std::__is_inplace_type<void>::value, "");
static_assert(!std::__is_inplace_type<int>::value, "");
static_assert(!std::__is_inplace_type<S>::value, "");
}