Type annotations in lib.d.ts are not type safe

[andrewvarga]

In lib.d.ts (TS 2.8.1) all the interfaces of WebGL objects like WebGLBuffer, WebGLTexture are empty, and so because of structural subtyping (duck typing), this code compiles without a problem:

let texture: WebGLTexture;
let buffer: WebGLBuffer = texture;

An external typing file I used for WebGL types solves this by adding dummyprops to these interfaces, which is a little hacky but works:
https://github.com/asgerf/dartify/blob/master/testcases/pixi/webgl.d.ts

I know this is intended behaviour for TypeScript but I was wondering if there is a better way to enforce type safety in situations like this?

[mhegazy]

i think this is the same as #5855

[andrewvarga]

Indeed.