add rustowl to rustaceanvim

[swaits]

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• This is not a bug report or a question (Please use issues for those).
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Feature description

From the README.md:

RustOwl visualizes ownership movement and lifetimes of variables. When you save Rust source code, it is analyzed, and the ownership and lifetimes of variables are visualized when you hover over a variable or function call.

This is useful enough, in my opinion, to become a default in rustaceanvim.

Why?

One might say, "anyone wanting this can just add it to their nvim config themselves." However, LSP config is often obtuse and opaque. The benefit of rustaceanvim is that it nicely configures everything for an out of the box experience. Since RustOwl needs to hook into the LSP config, it makes sense to sit next to all the other LSP config happening here.

Furthermore, the benefit of visualizing lifetimes could be useful to many new Rustaceans, and I'd hazard to say even many experienced Rustaceans. With as many people using rustaceanvim, I guess lots via LazyVim, the opportunity to make Rust more understandable, debuggable, and approachable for a large audience is significant.

Should it be on by default?

Great question. I think so. But I can see a valid argument for both sides of this.

[mrcjkb]

Hey 👋

Thanks for the suggestion. Unfortunately rustowl's license isn't compatible with rustaceanvim's licence, so I can't copy over their nvim plugin code.

It would probably make more sense to remove the hard dependency on nvim-lspconfig from the rustowl plugin and to make it work out of the box too.

[swaits]

Ugh, I didn't notice the license. That indeed is a clear dealbreaker.

I will cut them a ticket about changing to a permissive license instead of a viral license. Doesn't hurt to ask.

Edit: Oops, ignore that. They're already MPL. Yours is the viral license.

Another question: why do you need to copy the code? Can't it just be pulled in as a dependency?

[mrcjkb]

Both MPL and GPL are copyleft licenses that are not compatible with each other.

Can't it just be pulled in as a dependency?

Sure, I could do that, but removing the lspconfig dependency from rustowl wouldn't be any more effort and would result in a better UX.

[mrcjkb]

cordx56/rustowl#57

[swaits]

Thank you for submitting that issue! 🤞🏼