[ObjC] Implement @available in the Parser and AST

This patch adds a new AST node: ObjCAvailabilityCheckExpr, and teaches the
Parser and Sema to generate it. This node represents an availability check of
the form:

  @available(macos 10.10, *);

Which will eventually compile to a runtime check of the host's OS version. This
is the first patch of the feature I proposed here:
http://lists.llvm.org/pipermail/cfe-dev/2016-July/049851.html

Differential Revision: https://reviews.llvm.org/D22171

llvm-svn: 275654

1 files changed, 5 insertions, 1 deletions

diff --git a/clang/tools/libclang/CXCursor.cpp b/clang/tools/libclang/CXCursor.cpp
index 80bb569150e..19ab0f929c8 100644
--- a/clang/tools/libclang/CXCursor.cpp
+++ b/clang/tools/libclang/CXCursor.cpp
@@ -447,7 +447,11 @@ CXCursor cxcursor::MakeCXCursor(const Stmt *S, const Decl *Parent,
   case Stmt::ObjCBoolLiteralExprClass:
     K = CXCursor_ObjCBoolLiteralExpr;
     break;
-      
+
+  case Stmt::ObjCAvailabilityCheckExprClass:
+    K = CXCursor_ObjCAvailabilityCheckExpr;
+    break;
+
   case Stmt::ObjCBridgedCastExprClass:
     K = CXCursor_ObjCBridgedCastExpr;
     break;