Merge pull request #11427 from Microsoft/implictAnySelfRef

Do not get return type from contextual signature if we are already in process of getting return type of it

src/compiler/checker.ts

@@ -12771,7 +12771,10 @@ namespace ts {
             if (!contextualSignature) {
                 reportErrorsFromWidening(func, type);
             }
-            if (isUnitType(type) && !(contextualSignature && isLiteralContextualType(getReturnTypeOfSignature(contextualSignature)))) {
+            if (isUnitType(type) &&
+                !(contextualSignature &&
+                    isLiteralContextualType(
+                        contextualSignature === getSignatureFromDeclaration(func) ? type : getReturnTypeOfSignature(contextualSignature)))) {
                 type = getWidenedLiteralType(type);
             }
 

tests/baselines/reference/selfReference.js

@@ -0,0 +1,6 @@
+//// [selfReference.ts]
+declare function asFunction<T>(value: T): () => T;
+asFunction(() => { return 1; });
+
+//// [selfReference.js]
+asFunction(function () { return 1; });

tests/baselines/reference/selfReference.symbols

@@ -0,0 +1,11 @@
+=== tests/cases/compiler/selfReference.ts ===
+declare function asFunction<T>(value: T): () => T;
+>asFunction : Symbol(asFunction, Decl(selfReference.ts, 0, 0))
+>T : Symbol(T, Decl(selfReference.ts, 0, 28))
+>value : Symbol(value, Decl(selfReference.ts, 0, 31))
+>T : Symbol(T, Decl(selfReference.ts, 0, 28))
+>T : Symbol(T, Decl(selfReference.ts, 0, 28))
+
+asFunction(() => { return 1; });
+>asFunction : Symbol(asFunction, Decl(selfReference.ts, 0, 0))
+

tests/baselines/reference/selfReference.types

@@ -0,0 +1,14 @@
+=== tests/cases/compiler/selfReference.ts ===
+declare function asFunction<T>(value: T): () => T;
+>asFunction : <T>(value: T) => () => T
+>T : T
+>value : T
+>T : T
+>T : T
+
+asFunction(() => { return 1; });
+>asFunction(() => { return 1; }) : () => () => 1
+>asFunction : <T>(value: T) => () => T
+>() => { return 1; } : () => 1
+>1 : 1
+

tests/cases/compiler/selfReference.ts

@@ -0,0 +1,3 @@
+// @noImplicitAny: true
+declare function asFunction<T>(value: T): () => T;
+asFunction(() => { return 1; });