Check the return type of type guard functions

gcnew · gcnew · commit e52ed1a23a47 · 2017-07-20T02:49:20.000+03:00
diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
@@ -17996,6 +17996,8 @@ namespace ts {
                 return;
             }
 
+            checkSourceElement(node.type);
+
             const { parameterName } = node;
             if (isThisTypePredicate(typePredicate)) {
                 getTypeFromThisTypeNode(parameterName as ThisTypeNode);

Original file line number	Diff line number	Diff line change
`@@ -17996,6 +17996,8 @@ namespace ts {`
`17996`	`17996`	`return;`
`17997`	`17997`	`}`
`17998`	`17998`
	`17999`	`+ checkSourceElement(node.type);`
	`18000`	`+`
`17999`	`18001`	`const { parameterName } = node;`
`18000`	`18002`	`if (isThisTypePredicate(typePredicate)) {`
`18001`	`18003`	`getTypeFromThisTypeNode(parameterName as ThisTypeNode);`