feat: visibility for type aliases

[asterite]

Description

Problem

Part of #4515

Summary

Additional Context

Documentation

Check one:

• No documentation needed.
• Documentation included in this PR.
• [For Experimental Features] Documentation to be submitted in a separate PR.

PR Checklist

• I have tested the changes locally.
• I have formatted the changes with Prettier and/or cargo fmt on default settings.

[github-actions]

Changes to Brillig bytecode sizes

Generated at commit: 04752f7dd1f8882cb1aaad31943306f3f3431901, compared to commit: e8bbce71fde3fc7af410c30920c2a547389d8248

There are no changes in circuit sizes

[github-actions]

🚀 Deployed on https://66f453d955ee653ccf77c362--noir-docs.netlify.app

[TomAFrench]

checking something.

[TomAFrench]

mod foo {
    struct Foo {
        inner: Field
    }
    pub type Bar = Foo;
}

fn main() {
    // The `foo::Foo` raises a warning because we can't construct from a type alias currently
    // if we could then this would be entirely legal.
    let _: foo::Bar = foo::Foo { inner: 0 };
}

This PR currently allows us to expand the visibility of types by defining a type alias.

[jfecher]

This PR currently allows us to expand the visibility of types by defining a type alias.

I kinda like this feature 😅

[asterite]

It's interesting because the above code in Rust gives an error:

mod foo {
    struct Foo {
        pub inner: i32,
    }
    pub type Bar = Foo;
}

The error is:

Type Foo is more private than item Bar

However, if I make Foo be pub(crate):

mod foo {
    pub(crate) struct Foo {
        pub inner: i32,
    }
    pub type Bar = Foo;
}

that error no longer happens 🤔

I don't understand why Rust doesn't give an error in this case. Foo is still more private than Bar.

For now I'll make both cases give an error in Noir, but let me know if it should be like in Rust instead.

[asterite]

Done! I pushed a change to fix the above scenario.

I made it a warning, though, mainly because it's still a visibility thing and all of those are currently warnings.

[github-actions]

FYI @noir-lang/developerrelations on Noir doc changes.