Better error message on Flycheck Error message

[flipbit03]

I have commented on this S-unactionable issue that the Flycheck error message should maybe provide a hint about what tool it actually runs. Searching on some places on the Internet I've found multiple people, including myself, losing copious amounts of time on the same issue. So I've decided to make this very small PR :-)

From an user experience standpoint, the current error message is unhelpful to the end user, because the end user does not know exactly what it needs to check/fix (outdated, broken, or missing cargo clippy). In my own case, cargo clippy was actually missing altogether (developing off rust:1.59.0-bullseye official Docker image).

Thanks in advance!

[bjorn3]

I think it should only show that hint when you actually configured rust-analyzer to use clippy. rust-analyzer.checkOnSave.command defaults to check.

[Veykril]

Ye we use check by default. We do record stderr in this code path already though, so we should just emit that with the error message as the other match arm already does

[flipbit03]

This is strange. In my currently configured setup (Devcontainer/Codespaces) I do not have rust-analyzer.checkOnSave.command set to anything (so it should use the default value as you mentioned, check). Do you have any extra pointers on why adding clippy to the container fixed it?

Here's the Dockerfile for my Devcontainer (it's rather simple):

FROM rust:1.59.0-bullseye

# This fixed rust-analyzer error on each save.
RUN rustup component add clippy

# Install GCC (for Python), Python3 dev headers and PostgreSQL's headers/libraries.
RUN apt-get update && export DEBIAN_FRONTEND=noninteractive \
    && apt-get -y install --no-install-recommends libpq-dev pipenv gcc python3-dev

###############
# Create Jefferson
###############
ARG USER_NAME=jefferson
# Uid does not need to match outside UID in case of VSCode's Devcontainer (it is matched automatically)
ARG USER_UID=1000
ARG USER_GID=$USER_UID

RUN groupadd --gid $USER_GID $USER_NAME \
    && useradd --uid $USER_UID --gid $USER_GID -s /bin/bash -m $USER_NAME \
    && apt-get update \
    && apt-get -y install --no-install-recommends sudo \
    && echo $USER_NAME ALL=\(root\) NOPASSWD:ALL > /etc/sudoers.d/$USER_NAME \
    && chmod 0440 /etc/sudoers.d/$USER_NAME \
    # Docker without sudo support
    && groupadd docker \
    && usermod -a -G docker $USER_NAME

# Become Jefferson \o/
USER $USER_NAME

Thanks in advance!

NINJA EDIT: "rust-analyzer.checkOnSave.command": "clippy" was tucked in Devcontainer's devcontainer.json 🤦

Sorry for any trouble

[Veykril]

Good to know you figured out why :)
Regarding this PR, do you care to implement what I've noted down earlier?

We do record stderr in this code path already though, so we should just emit that with the error message as the other match arm already does

If not that's fine then I'll do that in a bit, just wanna know if we can close this PR otherwise.

[flipbit03]

@Veykril I am going to try to make it emit stderr. Updating this PR in a few. Thank you for the patience! (I'm looking to learn more and more about Rust in general 🙏 )

[flipbit03]

@Veykril as requested, the PR has been updated and we are now outputting the contents of stderr together with the final error message. Thank you for your time in reviewing this!

[bjorn3]

Maybe use from_utf8_lossy instead? That is infallible. In any case the error should say that the stderr is not valid UTF-8 if you keep using from_utf8.

[Veykril]

You don't want to use output.stderr here, we use streaming_output to fill in the error output into the error local here which is what contains the error (See the Err(e) branch below this one).

[flipbit03]

Thank you for your time @bjorn3 and @Veykril. I have updated my PR, now using error String variable to build the final output message.

[Veykril]

Thanks!
bors r+

[bors]

Build succeeded:

• Rust (macos-latest)
• Rust (ubuntu-latest)
• Rust (windows-latest)
• TypeScript (ubuntu-latest)
• TypeScript (windows-latest)