commit 7af39704ffca6cb484bea82856ff364f27adfbe1
author Eric Fiselier <eric@efcs.ca> Fri Mar 08 23:15:54 2019 +0000
committer Eric Fiselier <eric@efcs.ca> Fri Mar 08 23:15:54 2019 +0000
tree adad8c0caffc5208df02008daee1efd7c2232cd7
parent 975cb9a72111e83c3fb03b8cc476593ef3628ec9

Unbork `std::memory_order` ABI.

Summary:
We need to pin the underlying type of C++20' `std::memory_order` to match the C++17 version. Anything less is an ABI break.

At the moment it's `unsigned` before C++20 and `int` after. Or if you're using `-fshort-enums` it's `unsigned char` before C++20 and `int` after.

This patch explicitly specifies the underlying type of the  C++20 `memory_order` to be w/e type the compiler would have chosen for the C++17 version.

Reviewers: mclow.lists, ldionne

Reviewed By: ldionne

Subscribers: jfb, jdoerfert, #libc, zoecarver

Differential Revision: https://reviews.llvm.org/D59063

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@355755 91177308-0d34-0410-b5e6-96231b3b80d8