Libc++ is used as a system library on macOS and iOS (amongst others). In order
for users to be able to compile a binary that is intended to be deployed to an
older version of the platform, clang provides the
availability attribute <https://clang.llvm.org/docs/AttributeReference.html#availability>_
that can be placed on declarations to describe the lifecycle of a symbol in the
library.
See docs/DesignDocs/AvailabilityMarkup.rst for more information.
Differential Revision: https://reviews.llvm.org/D31739
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@302172 91177308-0d34-0410-b5e6-96231b3b80d8
Quite a few libcxx tests seem to follow the format:
#if _LIBCPP_STD_VER > X
// Do test.
#else
// Empty test.
#endif
We should instead use the UNSUPPORTED lit directive to exclude the test on
earlier C++ standards. This gives us a more accurate number of test passes
for those standards and avoids unnecessary conflicts with other lit
directives on the same tests.
Reviewers: bcraig, ericwf, mclow.lists
Differential revision: http://reviews.llvm.org/D20730
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@271108 91177308-0d34-0410-b5e6-96231b3b80d8
