Support Swift in platform availability attribute

Summary: This adds support for Swift platform availability attributes. It's largely a port of the changes made to https://github.com/apple/swift-clang/ for Swift availability attributes. Specifically, https://github.com/apple/swift-clang/commit/84b5a21c31cb5b0d7d958a478bc01964939b6952 and https://github.com/apple/swift-clang/commit/e5b87f265aede41c8381094bbf54e2715c8293b0 . The implementation of attribute_availability_swift is a little different and additional tests in test/Index/availability.c were added.

Reviewers: manmanren, friss, doug.gregor, arphaman, jfb, erik.pilkington, aaron.ballman

Reviewed By: aaron.ballman

Subscribers: aaron.ballman, ColinKinloch, jrmuizel, cfe-commits

Differential Revision: https://reviews.llvm.org/D50318

llvm-svn: 346633
diff --git a/clang/test/Sema/attr-availability-swift.c b/clang/test/Sema/attr-availability-swift.c
new file mode 100644
index 0000000..d77094c
--- /dev/null
+++ b/clang/test/Sema/attr-availability-swift.c
@@ -0,0 +1,29 @@
+// RUN: %clang_cc1 -triple x86_64-apple-darwin9 -fsyntax-only -fblocks -verify %s
+// RUN: %clang_cc1 -triple x86_64-apple-darwin9 -fsyntax-only -ast-dump %s | FileCheck %s
+//
+
+#if !__has_feature(attribute_availability_with_message)
+# error "Missing __has_feature"
+#endif
+
+#if __has_feature(attribute_availability_swift)
+# warning "okay"
+// expected-warning@-1{{okay}}
+#else
+# error "Missing __has_feature"
+#endif
+
+extern int noSwiftGlobal1 __attribute__((availability(swift, unavailable)));
+// CHECK: AvailabilityAttr {{.*}}swift 0 0 0 Unavailable "" ""
+extern int noSwiftGlobal1 __attribute__((availability(macosx, introduced=10.1))); // okay
+// CHECK: AvailabilityAttr {{.*}}Inherited swift 0 0 0 Unavailable "" ""
+// CHECK: AvailabilityAttr {{.*}}macos 10.1 0 0 "" ""
+extern int noSwiftGlobal1 __attribute__((availability(swift, unavailable, message="and this one has a message"))); // okay
+// CHECK: AvailabilityAttr {{.*}}Inherited macos 10.1 0 0 "" ""
+// CHECK: AvailabilityAttr {{.*}}swift 0 0 0 Unavailable "and this one has a message" ""
+extern int noSwiftGlobal2 __attribute__((availability(swift, introduced=5))); // expected-warning{{only 'unavailable' and 'deprecated' are supported for Swift availability}}
+// CHECK: VarDecl
+// CHECK-NOT: AvailabilityAttr
+extern int noSwiftGlobal3 __attribute__((availability(swift, deprecated, message="t")));
+// CHECK: VarDecl
+// CHECK: AvailabilityAttr {{.*}}swift 0 1 0 "t" ""