From 56b61ba758b5231d057bf2b3401f56c15bf669ec Mon Sep 17 00:00:00 2001
From: Slava Pestov <spestov@apple.com>
Date: Mon, 5 Jun 2017 21:43:34 -0700
Subject: [PATCH] Sema: Don't build ErrorTypes in simplifyType()

Instead, just build a new dependent member type with the
simplified base type.
---
 lib/Sema/ConstraintSystem.cpp | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/lib/Sema/ConstraintSystem.cpp b/lib/Sema/ConstraintSystem.cpp
index 17c4ad2bc78..a0c172652ef 100644
--- a/lib/Sema/ConstraintSystem.cpp
+++ b/lib/Sema/ConstraintSystem.cpp
@@ -1700,17 +1700,17 @@ Type simplifyTypeImpl(ConstraintSystem &cs, Type type, Fn getFixedTypeFn) {
         lookupBaseType = objectType;
       }
 
-      if (!lookupBaseType->mayHaveMembers()) return type;
-
-      auto subs = lookupBaseType->getContextSubstitutionMap(
+      if (lookupBaseType->mayHaveMembers()) {
+        auto subs = lookupBaseType->getContextSubstitutionMap(
           cs.DC->getParentModule(),
-          assocType->getDeclContext());
-      auto result = assocType->getDeclaredInterfaceType().subst(subs);
+            assocType->getDeclContext());
+        auto result = assocType->getDeclaredInterfaceType().subst(subs);
 
-      if (result)
-        return result;
+        if (result)
+          return result;
+      }
 
-      return DependentMemberType::get(ErrorType::get(newBase), assocType);
+      return DependentMemberType::get(lookupBaseType, assocType);
     }
 
     return type;