[libcxx] Start defining lit features for tests depending on availability

This patch removes some vendor-specific availability XFAILs from the
test suite. In the future, when a new feature is introduced in the
dylib, an availability macro should be created and a matching lit
feature should be created. That way, the test suite can XFAIL whenever
the implementation lacks the necessary feature instead of being
cluttered by vendor-specific annotations.

Right now, those vendor-specific annotations are still somewhat cluttering
the test suite by being in `config.py`, but at least they are localized.
In the future, we could design a way to define those less intrusively or
even automatically based on the availability macros that already exist
in <__config>.

llvm-svn: 353201

1 files changed, 6 insertions, 0 deletions

diff --git a/libcxx/docs/DesignDocs/AvailabilityMarkup.rst b/libcxx/docs/DesignDocs/AvailabilityMarkup.rst
index 4e6d80b50bf..f076dfecdaa 100644
--- a/libcxx/docs/DesignDocs/AvailabilityMarkup.rst
+++ b/libcxx/docs/DesignDocs/AvailabilityMarkup.rst
@@ -51,6 +51,12 @@ or on a particular symbol:
 
     _LIBCPP_OVERRIDABLE_FUNC_VIS _LIBCPP_AVAILABILITY_SIZED_NEW_DELETE void  operator delete(void* __p, std::size_t __sz) _NOEXCEPT;
 
+Furthermore, a lit feature should be added to match that availability macro,
+so that tests depending on that feature can be marked to XFAIL if the feature
+is not supported. This way, the test suite will work on platforms that have
+not shipped the feature yet. This can be done by adding the appropriate lit
+feature in test/config.py.
+
 
 Testing
 =======