Fix FunctionType emit when only parameter has no type

ajafff · ajafff · commit 66a401ae648b · 2018-09-11T09:39:11.000+02:00
Fixes: microsoft#27018
diff --git a/src/compiler/emitter.ts b/src/compiler/emitter.ts
@@ -2818,7 +2818,8 @@ namespace ts {
             const parameter = singleOrUndefined(parameters);
             return parameter
                 && parameter.pos === parentNode.pos // may not have parsed tokens between parent and parameter
-                && !(isArrowFunction(parentNode) && parentNode.type) // arrow function may not have return type annotation
+                && isArrowFunction(parentNode)      // only arrow functions may have simple arrow head
+                && !parentNode.type                 // arrow function may not have return type annotation
                 && !some(parentNode.decorators)     // parent may not have decorators
                 && !some(parentNode.modifiers)      // parent may not have modifiers
                 && !some(parentNode.typeParameters) // parent may not have type parameters
diff --git a/tests/baselines/reference/printerApi/printsNodeCorrectly.functionTypes.js b/tests/baselines/reference/printerApi/printsNodeCorrectly.functionTypes.js
@@ -1 +1 @@
-[args => any, <T>(args) => any, (...args) => any, (args?) => any, (args: any) => any, ({}) => any]
+[(args) => any, <T>(args) => any, (...args) => any, (args?) => any, (args: any) => any, ({}) => any]

Original file line number	Diff line number	Diff line change
`@@ -1 +1 @@`
`1`		`-[args => any, <T>(args) => any, (...args) => any, (args?) => any, (args: any) => any, ({}) => any]`
	`1`	`+[(args) => any, <T>(args) => any, (...args) => any, (args?) => any, (args: any) => any, ({}) => any]`