Use getParams() in findProtocolSelfReferences.

Author: rudkx

lib/AST/Decl.cpp

@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2018 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -3815,9 +3815,12 @@ ProtocolDecl::findProtocolSelfReferences(const ValueDecl *value,
     // Methods of non-final classes can only contain a covariant 'Self'
     // as a function result type.
     if (!allowCovariantParameters) {
-      auto inputType = type->castTo<AnyFunctionType>()->getInput();
-      auto inputKind = ::findProtocolSelfReferences(this, inputType,
-                                                    skipAssocTypes);
+      auto inputKind = SelfReferenceKind::None();
+      for (auto &elt : type->castTo<AnyFunctionType>()->getParams()) {
+        inputKind |= ::findProtocolSelfReferences(this, elt.getType(),
+                                                  skipAssocTypes);
+      }
+
       if (inputKind.parameter)
         return SelfReferenceKind::Other();
     }