Name clash with CSS extern

[acordex]

We were trying to make a "Rect" class, but Rect is defined in the css externs file:

ERROR - Variable Rect first declared in externs.zip//browser/w3c_css.js

However, Rect is not available in JS (at least not in Chrome). So this basically means that Closure is banning Rect from ever being used. Shouldn't the externs that aren't actually available as JS objects be obfuscated in some way so that they are less likely to clash with client code? E.g. W3c_Css_Rect or something like that?

Not sure if this is a problem or if we just don't understand how this is supposed to work.

[ChadKillingsworth]

What surprising is that has been present for pretty much the life of the project and you are the first person I recall reporting it.

@MatrixFrog There are lots of generic internal types in that extern and it is VERY old. I'm guessing changes here will be very difficult to land?

[Dominator008]

@ChadKillingsworth IMO instead of changing the externs, the compiler should be told that Rect isn't available in JavaScript and only serves to define a type. We should then do the renaming in the compiler internally / handle it differently. Changing it to things like w3c_css_Rect seems pretty messy and is a big loss for documentation purposes.

[ChadKillingsworth]

Fixing #1426 would give us a way to fix this as well.

[ricea]

I have been trying to find a way to solve a similar problem with externs/browser/streamsapi.js. It exports many, many symbols even though the Streams standard only exports 4: https://streams.spec.whatwg.org/#globals

This has been bugging me because I am writing an implementation of the standard in Javascript, and Closure thinks I am redefining everything.