From 649f2944137b21621f3556fea8aafe0ef5f2000e Mon Sep 17 00:00:00 2001
From: Daniel Rosenwasser <Daniel.Rosenwasser@microsoft.com>
Date: Tue, 17 Jul 2018 21:54:33 -0700
Subject: [PATCH] Elaborate on the first non-array type when object literals
 are compared against 'T | T[]'.

---
 src/compiler/checker.ts | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index e59641bed41..88983c9eff9 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -11182,7 +11182,8 @@ namespace ts {
                 if (reportErrors) {
                     const bestMatchingType =
                         findMatchingDiscriminantType(source, target) ||
-                        findMatchingTypeReferenceOrTypeAliasReference(source, target);
+                        findMatchingTypeReferenceOrTypeAliasReference(source, target) ||
+                        findBestTypeForObjectLiteral(source, target);
 
                     isRelatedTo(source, bestMatchingType || targetTypes[targetTypes.length - 1], /*reportErrors*/ true);
                 }
@@ -11207,6 +11208,11 @@ namespace ts {
                 }
             }
 
+            function findBestTypeForObjectLiteral(source: Type, unionTarget: UnionOrIntersectionType) {
+                if (getObjectFlags(source) & ObjectFlags.ObjectLiteral && forEachType(unionTarget, isArrayLikeType)) {
+                    return find(unionTarget.types, t => !isArrayLikeType(t));
+                }
+            }
 
             // Keep this up-to-date with the same logic within `getApparentTypeOfContextualType`, since they should behave similarly
             function findMatchingDiscriminantType(source: Type, target: UnionOrIntersectionType) {