Support using goog.require to import an ES6 module

It would be helpful – and likely even necessary – to be able to use goog.require to import ES6 modules in order to migrate a large codebase to the ES6 module system.

The wiki mentions interop and demonstrates doing a CommmonJS require of an ES6 module, but doesn’t mention using goog.require: https://github.com/google/closure-compiler/wiki/JS-Modules#module-interoperation

In basic experiments, importing a module by its transformed path (e.g. goog.require('module$path$to$module$file')) compiles correctly. This doesn’t seem like a stable or supported way of importing a module though.

I put together some experiments at https://gist.github.com/rictic/f042c2adf30101597fa5bd34a23d992d (buildable internal link: https://goto.google.com/js-module-interop-experiment) demonstrating different combinations of goog.module, goog.provide and ES6 modules as best as I understand the situation today.

Related bug: https://github.com/google/closure-compiler/issues/1877

[ChadKillingsworth]

I really need to go document this. It works with this form:

import * as Event from 'goog:goog.event';

[rictic]

@ChadKillingsworth This issue is for going the other direction. What should a user do, who wants to import an ES6 module from a file that uses goog.provide or goog.module?

In the terms of the gist, how would goog-user.js or global-user.js depend on es6-lib.js?