Use Cargo.toml instead of rust-project.json

[mo8it]

We can generate a Cargo.toml file containing a [[bin]] entry for every exercise.

This should make things much smoother and less hacky, especially because we have many issues related to the language server.

This should also enable us to use Cargo instead of rustc to run the exercises. That would especially make Clippy exercises less of a trouble. This approach also allows us to easily add dependencies to the exercises in case we want to do so in the future.

[mo8it]

Done in the v6 branch :D

[antoineco]

@mo8it I just tried the v6 branch and love the improvements from this PR, so first of all thank you for the impressive work!

I have a question regarding this statement:

we have many issues related to the language server

If anything, the current state of v6 seem to actually degrade the language server experience. Inside a fresh Git clone of the branch on Linux, rust-analyzer (latest stable) no longer emits diagnostics while editing an exercise.
Are there still any upcoming changes related to language server for v6, or am I doing something wrong?

[mo8it]

Thanks for your feedback 🥰

Yes, you are right, if you just clone the repository and try to edit the exercises, the language server will not work. This is one downside of the current approach. But this only affects developing exercises.

The new method of doing Rustlings is to install Rustlings using cargo install rustlings (not published yet), then running rustlings init. No repo cloning happens. Instead, the directory rustlings/ will be created where you find the exercises. The language server works there out of the box :)

I need to add a warning when people try to work on the exercises from the repository. Thanks pointing this out.

[antoineco]

Indeed Cargo.toml looks a lot more like what I'd expect now, appreciate the tip about rustlings init 👍

I spotted one issue though; out of the box, the language server is still showing the following diagnostic for every exercise file:

file not included in crate hierarchy [unlinked-file]

This is solved by editing the exercises' paths inside Cargo.toml:

 bin = [
- { name = "intro1", path = "../exercises/00_intro/intro1.rs" },
+ { name = "intro2", path = "exercises/00_intro/intro2.rs" },
- { name = "intro1", path = "../exercises/00_intro/intro1.rs" },
+ { name = "intro2", path = "exercises/00_intro/intro2.rs" },
 ...

I can open a new issue if you prefer. In this case, feel free to hide my comment as "off topic".

[mo8it]

Good catch! Thank you very much :D

It was without the prefix ../, but I messed it up at some point 😅
BTW, the v6 branch is not even in the beta phase yet. I really appreciate your excitement to try it out and your reporting of issues, but just to let you know that a beta version will be released in the next days :D

[mo8it]

@antoineco In case you want to test the beta release of v6, here is the issue for feedback with instruction of how to install it: #1960