a contrived example, but its very possible for this kind of situation to appear
in real code if the pragmas are spread out across a large file. You can test if
your version of clang supports namespaces on ``#pragma clang attribute`` with
-``__has_feature(pragma_clang_attribute_namespaces)``.
+``__has_extension(pragma_clang_attribute_namespaces)``.
Subject Match Rules
-------------------
//
// The Predicate field dictates the conditions under which the feature or
// extension will be made available.
+//
+// FEATURE(...) should be used to advertise support for standard language
+// features, whereas EXTENSION(...) should be used for clang extensions. Note
+// that many of the identifiers in this file don't follow this rule for backward
+// compatibility reasons.
+//
//===----------------------------------------------------------------------===//
#if !defined(FEATURE) && !defined(EXTENSION)
FEATURE(attribute_unavailable_with_message, true)
FEATURE(attribute_unused_on_fields, true)
FEATURE(attribute_diagnose_if_objc, true)
-FEATURE(pragma_clang_attribute_namespaces, true)
FEATURE(blocks, LangOpts.Blocks)
FEATURE(c_thread_safety_attributes, true)
FEATURE(cxx_exceptions, LangOpts.CXXExceptions)
EXTENSION(cxx_variable_templates, LangOpts.CPlusPlus)
// Miscellaneous language extensions
EXTENSION(overloadable_unmarked, true)
+EXTENSION(pragma_clang_attribute_namespaces, true)
#undef EXTENSION
#undef FEATURE