Cannot define a union type with a new signature type

This currently gives me parse error:

class A {

}

function test(x: string | new() => A) {
                          ~~~~~~~~~~ parse error    
}

Though this works:

function test(x: new() => A) {

}

[DanielRosenwasser]

I’d say that it’s advantageous to users to disallow this, since we force writers to be explicit for future readers.

But yes, I think parsing this and reporting an error would be helpful, such as:

A function or constructor type literal must be explicitly parenthesized in a union or intersection type.

or the following two separately:

A function type literal must be explicitly parenthesized in a union or intersection type.

A constructor type literal must be explicitly parenthesized in a union or intersection type.

[jbondc]

Hit this recently with intersection types. Patch (was a bit tricky) uses this message : Invalid type. To avoid ambiguity, add parentheses: '(new() => void)'