feat: Add completion for raw identifiers

[xNul]

Adds support for valid Rust completion of raw identifiers.

Previously, code completion of fields made via raw identifiers would not re-insert those raw identifiers, resulting in invalid Rust code. Now, code completion of fields made via raw identifiers do re-insert those raw identifiers, resulting in valid Rust code.

The same is true for all code completion instances for fields and compatible Rust identifiers.

[lnicola]

It might be worth renaming name to mod_name and adding a new function that does this.

[matklad]

bors r+

LGTM as is!

[matklad]

It might be worth renaming name to mod_name and adding a new function that does this.

@lnicola could you expand on this? I don't quite understand what do you mean here :)

[lnicola]

This method here doesn't have a great name and there's a bit of duplication between this PR and raw_ident_esc.

[bors]

Build succeeded:

• Rust (macos-latest)
• Rust (ubuntu-latest)
• Rust (windows-latest)
• TypeScript (ubuntu-latest)
• TypeScript (windows-latest)

[matklad]

Ah... The method has the right name I think -- it is supposed to be used as make::name, and it is named after the return type (ast::Name), like any other method out there. Ideally, we'd auto-generate all those!

And yeah, ideally we should move raw_ident_esc to some other place, not sure what that would be!

[xNul]

@lnicola I considered not duplicating and instead, creating a public helper function such as

pub fn raw_ident_verify(ident: &str) -> bool {
    let is_keyword = parser::SyntaxKind::from_keyword(ident).is_some();
    is_keyword && !matches!(ident, "self" | "crate" | "super" | "Self") 
}

which is used by both render_field and raw_ident_esc but decided not to when I read the "Scale of Changes" section in the dev docs. I have no problem with changing it though.

[lnicola]

The function name (heh) is fine, but it returns a module declaration.

[matklad]

pub fn name(text: &str) -> ast::Name {

it returns ast::Name?

[lnicola]

Ooh, right 🤦. It parses a module declaration but returns only the name. Don't mind me.