Use hasDynamicSelfType and add another test where the result type is complex and includes the non-dynamic self.

Author: gregomni

lib/Sema/TypeCheckProtocol.cpp

@@ -545,9 +545,10 @@ swift::matchWitness(
     // Result types must match.
     // FIXME: Could allow (trivial?) subtyping here.
     if (!ignoreReturnType) {
-      if (reqResultType->is<DynamicSelfType>()) {
+      if (reqResultType->hasDynamicSelfType()) {
         auto classDecl = witness->getDeclContext()->getSelfClassDecl();
-        if (!classDecl || classDecl->isFinal() || witnessResultType->is<DynamicSelfType>())
+        if (!classDecl || classDecl->isFinal() ||
+            witnessResultType->hasDynamicSelfType())
           reqResultType = reqResultType->eraseDynamicSelfType();
         witnessResultType = witnessResultType->eraseDynamicSelfType();
       }

test/decl/protocol/conforms/self.swift

@@ -104,4 +104,11 @@ final class C8902b : P8902 {
 class C8902c : P8902 {
     func f(_ x: Bool) -> Self { fatalError() }
 }
+protocol P8902complex {
+  associatedtype A
+  func f() -> (A, Self?)
+}
+final class C8902complex : P8902complex {
+  func f() -> (Bool, C8902complex?) { fatalError() }
+}