code gen depends on types

[dgoldstein0]

TypeScript Version: 2.6.1

Code

class Foo {
    bar(): void {
        console.log(this.x);
    }
}

class Bar extends Foo {
    x: Number;

    constructor() {
        super();
        this.x = 2;
    }

    bar() {
        super.bar();
        (super.bar as any)();
    }
} 

let b = new Bar();
b.bar()

Expected behavior:

I expect that the code generated for super.bar() and (super.bar as any)() behave the same - this code should console.log(2) twice.

Actual behavior:

The code logs 2, and then undefined.

The underlying issue is that super.bar() and (super.bar as any)() compile to different code. the former compiles to _super.prototype.bar.call(this);, but the as any changes the compilation to _super.prototype.bar();, and so super.bar is called with the wrong this when the cast is in place.

I was generally under the impression that code generation should be the same whether or not casts were present in the code, so I found this a bit surprising. that said, it was easy to change my code to avoid this pitfall.