1608269 - JSM modules should not modify their export list dynamically

Status: RESOLVED WONTFIX

(Firefox :: General, task, P5)

Description

[Dave Townsend [:mossop]]

ES6 modules cannot do this so we need to stop JSMs from doing it.

Comment 1

[Kris Maglione [:kmag]]

This is already not supported for JSMs. At least, not after they've already been imported. The exports are captured when the module is loaded and the same set is returned after that.

Comment 2

[Dave Townsend [:mossop]]

(In reply to Kris Maglione [:kmag] from comment #1)

This is already not supported for JSMs. At least, not after they've already been imported. The exports are captured when the module is loaded and the same set is returned after that.

Yes, but some (very few thankfully) modify it before they've been imported. See https://searchfox.org/mozilla-central/source/services/sync/modules/constants.js#137 for example.

Comment 3

[Kris Maglione [:kmag]]

That's true, but they don't do it in a way that's incompatible with ES6 modules. They can just be changed to use export statements, which will have approximately the same effect.

Comment 4

[Dave Townsend [:mossop]]

(In reply to Kris Maglione [:kmag] from comment #3)

That's true, but they don't do it in a way that's incompatible with ES6 modules. They can just be changed to use export statements, which will have approximately the same effect.

Yes, we want to prepare for that.

Better example: https://searchfox.org/mozilla-central/source/browser/components/migration/ChromeProfileMigrator.jsm#615

Comment 5

[Kris Maglione [:kmag]]

I don't think there's any preparation to be done. That will just be an ordinary part of converting those modules to ES6

Comment 6

[Tooru Fujisawa [:arai]]

I agree that this is not preparation step.
Each file that does this should be manually migrated, and this issue should be addressed at the same time.