Compiler outputs bad code when an (ES module) exported @typedef is assigned a value

[shicks]

The following code works correctly uncompiled:

// input0
/** @typedef {number} */
export const Bits = {};
Bits.of = () => 42;
Bits.of();

// input1
import {Bits} from './input0';
Bits.of();

But it compiles to

/** @const @typedef {number} */ var Bits$$module$input0 = {};
/** @return {!Bits$$module$input0} */
Bits$$module$input0.of = function() { return 42; };
Bits$$module$input0.of();
/** @const */ var module$input0 = {};
/** @typedef {Bits$$module$input0} */ module$input0.Bits;

module$input0.Bits.of();
/** @const */ var module$input1 = {};

Note that the child module calls module$input0.Bits.of() while the parent module calls Bits$$module$input0.of(). Moreover, the previous two lines (at the end of the parent) are (removing comments):

var module$input0 = {};
module$input0.Bits;
module$input0.Bits.of();

It's very clear that this will be a runtime error, since the module$input0.Bits stub is not actually defined. This works correctly for goog.modules and for single scripts. It's just ES modules that get it wrong.

[jplaisted]

Typedefs have special handling when rewriting ES6 modules. This logic predates me so I don't know why it exists. My guess is aliases of typedefs don't work, and this was the work around.

[jplaisted]

This will sort of get fixed soon when I change rewriting of imports to reference the orignal variable directly. The module object will still be broken, but unless you have like a for of loop over the module object you won't ever actually be referencing it.