Summary:
FreeBSD ships an old ABI for std::pair which requires that it have non-trivial copy/move constructors. Currently the non-trivial copy/move is achieved by providing explicit definitions of the constructors. This is problematic because it means the constructors don't SFINAE properly. In order to SFINAE copy/move constructors they have to be explicitly defaulted and hense non-trivial.
This patch attempts to provide SFINAE'ing copy/move constructors for std::pair while still making them non-trivial. It does this by adding a base class with a non-trivial copy constructor and then allowing pair's constructors to be generated by the compiler. This also allows the constructors to be constexpr.
Reviewers: emaste, theraven, rsmith, dim
Subscribers: cfe-commits
Differential Revision: https://reviews.llvm.org/D25389
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@283944 91177308-0d34-0410-b5e6-96231b3b80d8
This patch does the following:
* It renames `_LIBCPP_TRIVIAL_PAIR_COPY_CTOR` to `_LIBCPP_DEPRECATED_ABI_DISABLE_PAIR_TRIVIAL_COPY_CTOR`.
* It automatically enables this option on FreeBSD in ABI V1, since that's the current ABI FreeBSD ships.
* It cleans up the handling of this option in `std::pair`.
I would like the sign off from the FreeBSD maintainers. They will no longer need to keep their `__config` changes downstream.
I'm still hoping to come up with a better way to maintain the ABI without needing these constructors.
Reviewed in https://reviews.llvm.org/D21329
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@275749 91177308-0d34-0410-b5e6-96231b3b80d8
