Add regression test

Author: ahejlsberg

testdata/tests/cases/compiler/jsxFunctionTypeChildren.tsx

@@ -0,0 +1,27 @@
+// @strict: true
+// @target: esnext
+// @noEmit: true
+// @jsx: preserve
+
+// https://github.com/microsoft/typescript-go/issues/2703
+
+/// <reference path="/.lib/react.d.ts" />
+
+import * as React from 'react';
+
+type BaseProps = { locale: string };
+
+type Props<T extends BaseProps> = {
+    children: (props: T) => React.ReactNode;
+} & T;
+
+declare function Comp<T extends BaseProps>(props: Props<T>): JSX.Element;
+
+const bp: BaseProps = { locale: 'en' };
+
+// Error in ts-go: Type '(props: ...) => Element' is not assignable to
+// type '((props: ...) => ReactNode) & {}'.
+const el = <Comp {...bp}>{(props) => <div>{props.locale}</div>}</Comp>;
+
+// But the equivalent non-JSX call works fine:
+Comp({ ...bp, children: (props) => <div>{props.locale}</div> });