Implement LWG 2904.
Summary:
- Removed the move-constructibe requirement from copy-assignable.
- Updated `__assign_alt` such that we direct initialize if
`_Tp` can be `nothrow`-constructible from `_Arg`, or `_Tp`'s
move construction can throw. Otherwise, construct a temporary and move it.
- Updated the tests to remove the pre-LWG2904 path.
Depends on D32671.
Reviewers: EricWF, CaseyCarter
Reviewed By: EricWF
Differential Revision: https://reviews.llvm.org/D33965
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@304891 91177308-0d34-0410-b5e6-96231b3b80d8
4 files changed