feat: Bool to enum assist

[rmehri01]

This adds the bool_to_enum assist, which converts the type of boolean local variables, fields, constants and statics to a new enum type, making it easier to distinguish the meaning of true and false by renaming the variants.

Closes #14779

[rmehri01]

I think it would be nice to handle cross file and module references too, especially in the case of constants. I had a version before where I would just check to see if the ctx file is different than the usage file, then I would insert an import to the new enum, which seemed to work out alright for basic files but this doesn't handle modules within a file so I was wondering if there is another approach that would be nicer?

[rmehri01]

Maybe handling a test like this could be nice?

    #[test]
    fn const_in_module() {
        check_assist(
            bool_to_enum,
            r#"
fn main() {
    if foo::FOO {
        println!("foo");
    }
}

mod foo {
    pub const $0FOO: bool = true;
}
"#,
            r#"
use foo::Bool;

fn main() {
    if foo::FOO == Bool::True {
        println!("foo");
    }
}

mod foo {
    #[derive(PartialEq, Eq)]
    pub enum $0Bool { True, False }

    pub const FOO: Bool = Bool::True;
}
"#,
        )
    }

[rmehri01]

Two approaches may be:

1. Use ctx.sema.scope to check if the definition and usage are in different modules and then do the appropriate insert_use.
2. Use is_ methods for each of the variants, as done in generate_enum_is_method so that there are no imports needed.

[Veykril]

Handling it cross modules properly would be great yes, you might be able to check on crates\ide-assists\src\handlers\extract_struct_from_enum_variant.rs how things are done there. Iirc it needs to import stuff as well when rewriting other files

[rmehri01]

I see, thanks for the pointer! I think I've got it to work in a similar way now using the import approach. The only problem is I can't seem to get the tabstop snippet to show up in the right place because of the added import, so I've just removed the tabstop for now.

[Veykril]

Handling it cross modules properly would be great yes, you might be able to check on crates\ide-assists\src\handlers\extract_struct_from_enum_variant.rs how things are done there. Iirc it needs to import stuff as well when rewriting other files

[bors]

☔ The latest upstream changes (presumably #15524) made this pull request unmergeable. Please resolve the merge conflicts.

[rmehri01]

@rustbot review

[Veykril]

Thanks! Really looking forward to using this assist 🎉
@bors r+

[bors]

📌 Commit 93562dd has been approved by Veykril

It is now in the queue for this repository.

[bors]

⌛ Testing commit 93562dd with merge df75809...

[bors]

☀️ Test successful - checks-actions
Approved by: Veykril
Pushing df75809 to master...