rust-lang/rust-analyzer · error · io::Error

{e:?}: {error}

Error message

{e:?}: {error}

What it means

An error-aggregation format string in `command.rs`'s `run`: after pumping the child process's stdout/stderr, accumulated stdout parse errors and stderr errors are merged into one message prefixed with the terminating process error `e`. It fires when a spawned cargo/flycheck-style command either failed to launch/exit cleanly or produced output the parser could not handle, and reports all of it at once.

Source

Thrown at crates/rust-analyzer/src/command.rs:117

                if let Some(t) = self.parser.from_stderr_line(line, &mut stderr_errors) {
                    self.sender.send(t).unwrap();
                    read_at_least_one_stderr_message = true;
                }
            },
            &mut || {
                if let Some(t) = self.parser.from_eof() {
                    self.sender.send(t).unwrap();
                }
            },
        );

        let read_at_least_one_message =
            read_at_least_one_stdout_message || read_at_least_one_stderr_message;
        let mut error = stdout_errors;
        error.push_str(&stderr_errors);
        match output {
            Ok(_) => Ok((read_at_least_one_message, error)),
            Err(e) => Err(io::Error::new(e.kind(), format!("{e:?}: {error}"))),
        }
    }
}

/// 'Join On Drop' wrapper for a child process.
///
/// This wrapper kills the process when the wrapper is dropped.
struct JodGroupChild(Box<dyn ChildWrapper>);

impl Drop for JodGroupChild {
    fn drop(&mut self) {
        _ = self.0.kill();
        _ = self.0.wait();
    }
}

/// A handle to a shell command, such as cargo for diagnostics (flycheck).
pub(crate) struct CommandHandle<T> {

View on GitHub (pinned to e8f7e90aa3)

Solutions

1. Inspect the trailing stderr text in the message — it usually contains the real cause from the child process
2. Ensure the command and arguments configured for the tool are correct and the binary exists on PATH
3. Check for environment issues (working directory, toolchain overrides) that make the child fail on startup
4. If output is truncated or interleaved, increase buffer/log fidelity before the parse errors are produced

When it happens

Trigger: Thrown at crates/rust-analyzer/src/command.rs:117 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of rust-lang/rust-analyzer@e8f7e90aa3 (2026-09-03). Data as JSON: /api/errors/1b18a08be8b0d8b5. Report an issue: GitHub.