Recursively export constants from modules

[kubouch]

Description

#9773 introduced constants to modules and allowed to export them, but only within one level. This PR:

• allows recursive exporting of constants from all submodules
• fixes submodule imports in a list import pattern
• makes sure exported constants are actual constants

Should unblock #9678

Example:

module spam {
    export module eggs {
        export module bacon {
            export const viking = 'eats'
        }
    }
}

use spam 
print $spam.eggs.bacon.viking  # prints 'eats'

use spam [eggs]
print $eggs.bacon.viking  # prints 'eats'

use spam eggs bacon viking
print $viking  # prints 'eats'

Limitation 1:

Considering the above spam module, attempting to get eggs bacon from spam module doesn't work directly:

use spam [ eggs bacon ]  # attempts to load `eggs`, then `bacon`
use spam [ "eggs bacon" ]  # obviously wrong name for a constant, but doesn't work also for commands

Workaround (for example):

use spam eggs
use eggs [ bacon ]

print $bacon.viking  # prints 'eats'

I'm thinking I'll just leave it in, as you can easily work around this. It is also a limitation of the import pattern in general, not just constants.

Limitation 2:

overlay use successfully imports the constants, but overlay hide does not hide them, even though it seems to hide normal variables successfully. This needs more investigation.

User-Facing Changes

Allows recursive constant exports from submodules.

Tests + Formatting

After Submitting

[kubouch]

Just discovered that when you import constants with overlay use, they won't be hidden when you call overlay hide. I'm not sure why. I think I'll remove the overlay use support for constants until it gets resolved.

[amtoine]

this looks like a very good PR to me, very good job 👌

and i love your examples 🙏 ❤️

i just have a question about one test 😏

[amtoine]

also, maybe we should wait for after the release at this point?

[kubouch]

I'd personally include it in the release, since the original export const implementation had some rough edges that are easy to encounter. We could ship with a more polished experience.

[amtoine]

thanks for answering my thread @kubouch 🙏

[WindSoilder]

Thanks! LGTM! I've tried and played with it, and it works pretty good!

[amtoine]

let's land this before we freeze for the release for real 🥳