RLS panics when invoked from master rls-vscode

[tchebb]

cb2206e ("Add missing full_docs and show_hover_context config keys") exposed a bug in RLS where it panics when full_docs is specified as null. I have submitted rust-lang/rls#1192 to fix the bug in RLS; however, it might be prudent to revert cb2206e or specify false instead of null for full_docs so as to not break users who don't update RLS.

Example panic:

thread '<unnamed>' panicked at 'internal error: entered unreachable code', src/config.rs:111:33

[olix0r]

I'm seeing a similar panic using version 0.5.4:

thread '<unnamed>' panicked at 'internal error: entered unreachable code', src/tools/rls/src/config.rs:111:33
note: Run with `RUST_BACKTRACE=1` for a backtrace.
thread '<unnamed>' panicked at 'called `Result::unwrap()` on an `Err` value: "PoisonError { inner: .. }"', src/libcore/result.rs:1009:5
thread '<unnamed>' panicked at 'called `Result::unwrap()` on an `Err` value: "PoisonError { inner: .. }"', src/libcore/result.rs:1009:5
thread '<unnamed>' panicked at 'called `Result::unwrap()` on an `Err` value: "PoisonError { inner: .. }"', src/libcore/result.rs:1009:5

[tchebb]

This is weird; I'm not able to reproduce this issue now even though it should be present on my system.

Regardless, RLS doesn't seem to have released the fix on their end for this issue yet (although it is in master). As a temporary workaround, specify rust.full_docs in settings.json to be either true or false (false is supposed to be the default). The bug is that, when we pass null for that option to RLS, it fails to set the default internally and crashes, so explicitly specifying the setting should fix it.

[Xanewok]

That's weird, RLS stable should contain the fix from rust-lang/rls#1192. Which RLS version are you using?

[tchebb]

@Xanewok ah, that would explain why I couldn't reproduce it. I didn't see my fix in the latest RLS release tag, but I must have been looking at the wrong thing.

[Xanewok]

Yeah, my bad - we stopped tracking git releases and just ride the trains with regular Rust releases. It might be worth doing that again.

@olix0r what is your rls --version?

[olix0r]

@Xanewok I was probably on a slightly older version -- since commenting I updated to the most recent I don't see the issue anymore.

[Xanewok]

Glad to hear that! I'll close this issue, then.