Check Java and Rustup versions on startup

[fpoli]

As described in the readme, the extension currently requires Java >=12 Java >=11 and Rustup >=1.23. It would be useful to check these versions at startup, as part of the prerequisite checks, reporting an useful error message in case Java/Rustup is not up to date.

Feel free to ask for more information if you are interested in working on this!

[Aurel300]

I think the requirement is >= 11? That is what I am running locally.

[fpoli]

I think the requirement is >= 11? That is what I am running locally.

Oh, you are right! The class file version 55.0 corresponds to Java 11, not 12.

[quinn-dougherty]

should also be able to configure exactly which rustup and javac bins ought to be used.

[fpoli]

The javac to be used should already be configurable with this setting:

Prusti-assistant: Java Home
Specifies the path of the Java home folder (leave empty to auto-detect).

We could do something similar with rustup. What's your use case? Do you have multiple rustup binaries or is it just not in your program path?

[quinn-dougherty]

I would like prusti to be sensitive to direnv (i tried fiddling a little with the vscode direnv options). I currently need a user-wide installation of rustup in order for prusti to work, which completely breaks my rust-analyzer config elsewhere, since usually direnv is what works.

[fpoli]

I opened an issue to make rustup's path configurable: #246

I don't have much spare time these days, but I'd be happy to review and merge any contribution :)