Merge pull request microsoft#32077 from andrewbranch/bug/31114

andrewbranch · web-flow · commit 16bbb4d002d3 · 2019-07-03T10:10:10.000-07:00
Fix incorrect noImplicitAny error on contextual union function signature
diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
@@ -19129,7 +19129,9 @@ namespace ts {
                 }
             }
             // Result is union of signatures collected (return type is union of return types of this signature set)
-            return signatureList && createUnionSignature(signatureList[0], signatureList);
+            if (signatureList) {
+                return signatureList.length === 1 ? signatureList[0] : createUnionSignature(signatureList[0], signatureList);
+            }
         }
 
         function checkSpreadExpression(node: SpreadElement, checkMode?: CheckMode): Type {
diff --git a/tests/baselines/reference/functionExpressionContextualTyping3.js b/tests/baselines/reference/functionExpressionContextualTyping3.js
@@ -0,0 +1,8 @@
+//// [functionExpressionContextualTyping3.ts]
+// #31114
+declare function f<T>(value: T | number): void;
+f((a: any) => "")
+
+
+//// [functionExpressionContextualTyping3.js]
+f(function (a) { return ""; });
diff --git a/tests/baselines/reference/functionExpressionContextualTyping3.symbols b/tests/baselines/reference/functionExpressionContextualTyping3.symbols
@@ -0,0 +1,12 @@
+=== tests/cases/conformance/expressions/contextualTyping/functionExpressionContextualTyping3.ts ===
+// #31114
+declare function f<T>(value: T | number): void;
+>f : Symbol(f, Decl(functionExpressionContextualTyping3.ts, 0, 0))
+>T : Symbol(T, Decl(functionExpressionContextualTyping3.ts, 1, 19))
+>value : Symbol(value, Decl(functionExpressionContextualTyping3.ts, 1, 22))
+>T : Symbol(T, Decl(functionExpressionContextualTyping3.ts, 1, 19))
+
+f((a: any) => "")
+>f : Symbol(f, Decl(functionExpressionContextualTyping3.ts, 0, 0))
+>a : Symbol(a, Decl(functionExpressionContextualTyping3.ts, 2, 3))
+
diff --git a/tests/baselines/reference/functionExpressionContextualTyping3.types b/tests/baselines/reference/functionExpressionContextualTyping3.types
@@ -0,0 +1,13 @@
+=== tests/cases/conformance/expressions/contextualTyping/functionExpressionContextualTyping3.ts ===
+// #31114
+declare function f<T>(value: T | number): void;
+>f : <T>(value: number | T) => void
+>value : number | T
+
+f((a: any) => "")
+>f((a: any) => "") : void
+>f : <T>(value: number | T) => void
+>(a: any) => "" : (a: any) => ""
+>a : any
+>"" : ""
+
diff --git a/tests/cases/conformance/expressions/contextualTyping/functionExpressionContextualTyping3.ts b/tests/cases/conformance/expressions/contextualTyping/functionExpressionContextualTyping3.ts
@@ -0,0 +1,5 @@
+// @noImplicitAny: true
+
+// #31114
+declare function f<T>(value: T | number): void;
+f((a: any) => "")

Original file line number	Diff line number	Diff line change
`@@ -19129,7 +19129,9 @@ namespace ts {`
`19129`	`19129`	`}`
`19130`	`19130`	`}`
`19131`	`19131`	`// Result is union of signatures collected (return type is union of return types of this signature set)`
`19132`		`- return signatureList && createUnionSignature(signatureList[0], signatureList);`
	`19132`	`+ if (signatureList) {`
	`19133`	`+ return signatureList.length === 1 ? signatureList[0] : createUnionSignature(signatureList[0], signatureList);`
	`19134`	`+ }`
`19133`	`19135`	`}`
`19134`	`19136`
`19135`	`19137`	`function checkSpreadExpression(node: SpreadElement, checkMode?: CheckMode): Type {`