From 9df95fee79811c6d55e9906fb739c2e53aae3649 Mon Sep 17 00:00:00 2001
From: Daniel Rosenwasser <Daniel.Rosenwasser@microsoft.com>
Date: Thu, 21 Jun 2018 13:13:26 -0700
Subject: [PATCH] Expand better error messages to anonymous object types with
 identical type aliases.

---
 src/compiler/checker.ts | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 08bd281532..92019736c3 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -10862,15 +10862,13 @@ namespace ts {
 
             function findMatchingTypeReferenceOrTypeAliasReference(source: Type, unionTarget: UnionOrIntersectionType) {
                 if (source.flags & TypeFlags.Object && (source as ObjectType).objectFlags & (ObjectFlags.Reference | ObjectFlags.Anonymous) && unionTarget.flags & TypeFlags.Union) {
-                    return find(unionTarget.types, t => {
-                        if (t.flags & TypeFlags.Object) {
-                            if ((source as ObjectType).objectFlags & (t as ObjectType).objectFlags & ObjectFlags.Reference) {
-                                return (source as TypeReference).target === (t as TypeReference).target;
+                    return find(unionTarget.types, target => {
+                        if (target.flags & TypeFlags.Object) {
+                            if ((source as ObjectType).objectFlags & (target as ObjectType).objectFlags & ObjectFlags.Reference) {
+                                return (source as TypeReference).target === (target as TypeReference).target;
                             }
-                            if ((source as ObjectType).objectFlags & (t as ObjectType).objectFlags & ObjectFlags.Anonymous) {
-                                // TODO (drosen): Not sure why the following isn't sufficient.
-                                // return !!(source as AnonymousType).aliasSymbol && (source as AnonymousType).aliasSymbol === (target as AnonymousType).aliasSymbol;
-                                return false;
+                            if ((source as ObjectType).objectFlags & (target as ObjectType).objectFlags & ObjectFlags.Anonymous) {
+                                return !!(source as AnonymousType).aliasSymbol && (source as AnonymousType).aliasSymbol === (target as AnonymousType).aliasSymbol;
                             }
                         }
                         return false;