From c5ab4735ac01d316e4384e5ea398bd8d271c2ff0 Mon Sep 17 00:00:00 2001
From: Anders Hejlsberg <andersh@microsoft.com>
Date: Wed, 16 Nov 2016 06:48:51 -0800
Subject: [PATCH] Resolve upfront so recursive mapped types appear empty

---
 src/compiler/checker.ts | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 44bbfbc9ad5..846bb288d6b 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -4489,6 +4489,8 @@ namespace ts {
             const members: SymbolTable = createMap<Symbol>();
             let stringIndexInfo: IndexInfo;
             let numberIndexInfo: IndexInfo;
+            // Resolve upfront such that recursive references see an empty object type.
+            setStructuredTypeMembers(type, emptySymbols, emptyArray, emptyArray, undefined, undefined);
             // In { [P in K]: T }, we refer to P as the type parameter type, K as the constraint type,
             // and T as the template type.
             const typeParameter = getTypeParameterFromMappedType(type);