From fc85ba9e6a372b1f256e663380457b097c7b9c9d Mon Sep 17 00:00:00 2001
From: Anders Hejlsberg <andersh@microsoft.com>
Date: Fri, 6 Apr 2018 09:52:00 -0700
Subject: [PATCH] Limit getLiteralTypeFromPropertyName to only return
 string-like types

---
 src/compiler/checker.ts | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index ff3d53229ba..216854e9b6e 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -8108,10 +8108,16 @@ namespace ts {
         }
 
         function getLiteralTypeFromPropertyName(prop: Symbol) {
-            if (getDeclarationModifierFlagsFromSymbol(prop) & ModifierFlags.NonPublicAccessibilityModifier || isKnownSymbol(prop)) {
-                return neverType;
+            if (!(getDeclarationModifierFlagsFromSymbol(prop) & ModifierFlags.NonPublicAccessibilityModifier)) {
+                const nameType = getLateBoundSymbol(prop).nameType;
+                if (nameType) {
+                    return nameType.flags & TypeFlags.StringLiteral ? nameType : neverType;
+                }
+                if (!isKnownSymbol(prop)) {
+                    return getLiteralType(symbolName(prop));
+                }
             }
-            return getLateBoundSymbol(prop).nameType || getLiteralType(symbolName(prop));
+            return neverType;
         }
 
         function getLiteralTypeFromPropertyNames(type: Type) {