AST: Hack up computeDefaultMap() for removal of multiple parameter lists

Author: slavapestov

lib/AST/Type.cpp

@@ -841,8 +841,11 @@ swift::computeDefaultMap(ArrayRef<AnyFunctionType::Param> params,
   // Find the corresponding parameter list.
   const ParameterList *paramList = nullptr;
   if (auto *func = dyn_cast<AbstractFunctionDecl>(paramOwner)) {
-    if (level < func->getNumParameterLists())
-      paramList = func->getParameterList(level);
+    if (func->getImplicitSelfDecl()) {
+      if (level == 1)
+        paramList = func->getParameters();
+    } else if (level == 0)
+      paramList = func->getParameters();
   } else if (auto *subscript = dyn_cast<SubscriptDecl>(paramOwner)) {
     if (level == 1)
       paramList = subscript->getIndices();