Small change in rustup rust-src component breaks rust-analyzer

[ddboline]

After upgrading rust to 1.47.0 via rustup I get the following error from rust-analyzer:

rust-analyzer failed to load workspace: Failed to find sysroot for Cargo.toml file /home/ddboline/setup_files/build/garmin_rust/Cargo.toml. Is rust-src installed?: could not find libcore in sysroot path `/home/ddboline/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/src/`

This appears to be the result of ~/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/src being renamed to ~/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library, creating a symlink from library to src serves as a workaround.

[bjorn3]

Which version of rust-analyzer are you using? This should have been fixed a while ago.

[ddboline]

I'm using it through the rust-analyzer VSCode extension, which is v0.2.336.

[jonas-schievink]

I can't reproduce this locally

[robatipoor]

after update to rust 1.47 stable version I got the same error message in linux
rustup component add rust-src --toolchain stable
info: component 'rust-src' is up to date
ls $(rustc --print sysroot)/lib/rustlib/src/rust/src
liballoc libcore libstd
rust-analyzer --version
rust-analyzer e5f252a
echo $RUST_SRC_PATH
/home/username/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/src

[julientregoat]

same for me after updating to 1.47, but for some reason the src isn't there despite being installed nvm didn't read, it was renamed to library 😅

[lnicola]

Do you have RUST_SRC_PATH set?

[robatipoor]

Do you have RUST_SRC_PATH set?

yes
echo $RUST_SRC_PATH
/home/username/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/src

[lnicola]

That path has recently changed, as @ddboline has noticed. You should unset the variable or fix it.

[ddboline]

@lnicola Yep, that was the problem, a forgotten RUST_SRC_PATH entry in ~/.bash_profile, I'm gonna go ahead and close this issue.

[flodiebold]

Maybe we could try $RUST_SRC_PATH/../library if $RUST_SRC_PATH doesn't work 🤔

[SomeoneToIgnore]

If I got the idea right, we recommend unsetting this variable to use RA, don't we?
Can we detect it on startup and show a warning pop-up or similar?

[lnicola]

There's already a fixme comment to drop support for the old path in 1.47, though we could wait for one more release. So adding one more workaround for an env variable we don't recommend the users to set that points to the old path is maybe too much?

[flodiebold]

I don't think there's a big cost to these workarounds, so I don't really see a reason to eagerly remove support for the old path. I do think RUST_SRC_PATH often causes problems, so it makes sense to warn users about it, but if we can just keep functioning in more situations, I don't see a reason not to. Or in other words, I don't see the sense in breaking people's setups just because some other people's similar setups are already broken. For every user that notices that things don't work and investigates, there's probably a bunch more that don't and just think RA isn't very good.

[flodiebold]

But also, while we recommend not using RUST_SRC_PATH, I think there are setups where it's needed (otherwise we should just remove the support). So I don't think we can just show a warning on every startup.