Summary:
std::tuple marks its constructors as noexcept when the corresponding
memberwise constructors are noexcept too -- this commit improves std::pair
so that it behaves the same.
Note:
I did not add support in the explicit and non-explicit `pair(_Tuple&& __p)`
constructors because those are non-standard extensions, and supporting them
properly is tedious (we have to copy the rvalue-referenceness of the deduced
_Tuple&& onto the result of tuple_element).
<rdar://problem/29537079>
Reviewers: mclow.lists, EricWF
Subscribers: christof, llvm-commits
Differential Revision: https://reviews.llvm.org/D48669
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@348824 91177308-0d34-0410-b5e6-96231b3b80d8
