Summary:
Currently `std::variant` always uses an unsigned int to store the variant index. However this isn't nessesary and causes `std::variant` to be larger than it needs to be in most cases.
This patch changes the index type to be `unsigned char` when possible, and `unsigned short` or `unsigned int` otherwise, depending on the size (Although it's questionable if it's even possible to create a variant with 65535 elements.
Unfortunately this change is an ABI break, and as such is only enabled in ABI v2.
Reviewers: mpark
Reviewed By: mpark
Subscribers: cfe-commits
Differential Revision: https://reviews.llvm.org/D40210
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@318621 91177308-0d34-0410-b5e6-96231b3b80d8
These tests are failing in XCode 8.0, 8.1, and 8.2, but not in Xcode
8.3. Annoyingly the version numbering for clang does not follow Xcode
and is bumped to 8.1 only in Xcode 8.3. So Xfailing apple-clang-8.0
should catch all cases here.
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@296704 91177308-0d34-0410-b5e6-96231b3b80d8
