From dacc851434af9bbf2388a6db1438acabc2d886ef Mon Sep 17 00:00:00 2001
From: Anders Hejlsberg <andersh@microsoft.com>
Date: Mon, 14 Aug 2017 09:01:50 +0200
Subject: [PATCH] No contextual return type when type is circular

---
 src/compiler/checker.ts | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 07c94bd746..1ba33f8c82 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -6576,6 +6576,10 @@ namespace ts {
             return signature.resolvedReturnType;
         }
 
+        function isResolvingReturnTypeOfSignature(signature: Signature) {
+            return !signature.resolvedReturnType && findResolutionCycleStartIndex(signature, TypeSystemPropertyName.ResolvedReturnType) >= 0;
+        }
+
         function getRestTypeOfSignature(signature: Signature): Type {
             if (signature.hasRestParameter) {
                 const type = getTypeOfSymbol(lastOrUndefined(signature.parameters));
@@ -12949,7 +12953,7 @@ namespace ts {
             // Otherwise, if the containing function is contextually typed by a function type with exactly one call signature
             // and that call signature is non-generic, return statements are contextually typed by the return type of the signature
             const signature = getContextualSignatureForFunctionLikeDeclaration(<FunctionExpression>functionDecl);
-            if (signature) {
+            if (signature && !isResolvingReturnTypeOfSignature(signature)) {
                 return getReturnTypeOfSignature(signature);
             }