[test] add a dynamic self test file

Author: Suyash Srijan

test/PrintAsObjC/dynamicself.swift

@@ -0,0 +1,30 @@
+// RUN: %empty-directory(%t)
+// RUN: %target-swift-frontend(mock-sdk: %clang-importer-sdk) -emit-module -o %t %s -module-name dynamicself -disable-objc-attr-requires-foundation-module
+// RUN: %target-swift-frontend(mock-sdk: %clang-importer-sdk) -parse-as-library %t/dynamicself.swiftmodule -typecheck -emit-objc-header-path %t/dynamicself.h -disable-objc-attr-requires-foundation-module
+// RUN: %FileCheck %s < %t/dynamicself.h
+// RUN: %check-in-clang %t/dynamicself.h
+
+// REQUIRES: objc_interop
+
+import Foundation
+
+// CHECK-LABEL: @protocol FooProtocol
+// CHECK-NEXT:    - (nonnull instancetype)fooFunc SWIFT_WARN_UNUSED_RESULT;
+// CHECK-NEXT:    - (nullable instancetype)optionalFooFunc SWIFT_WARN_UNUSED_RESULT;
+// CHECK-NEXT:  @end
+
+@objc protocol FooProtocol {
+  func fooFunc() -> Self
+  func optionalFooFunc() -> Self?
+}
+
+// CHECK-LABEL: @interface BarClass : NSObject <FooProtocol>
+// CHECK-NEXT:    - (nonnull instancetype)fooFunc SWIFT_WARN_UNUSED_RESULT;
+// CHECK-NEXT:    - (nullable instancetype)optionalFooFunc SWIFT_WARN_UNUSED_RESULT;
+// CHECK-NEXT:    - (nonnull instancetype)init OBJC_DESIGNATED_INITIALIZER;
+// CHECK-NEXT:  @end
+
+@objc @objcMembers class BarClass: NSObject, FooProtocol {
+  func fooFunc() -> Self { return self }
+  func optionalFooFunc() -> Self? { return self }
+}