rust-lang/rust-analyzer · error

{message}

Error message

{message}

What it means

show_and_log_error displays an arbitrary message string to the LSP client as a window/showMessage error notification and simultaneously logs it (with optional additional info) to the server's error log. The `{message}` itself is dynamic; it is rust-analyzer's generic channel for surfacing fatal-ish runtime problems to the user.

Source

Thrown at crates/rust-analyzer/src/lsp/utils.rs:75

                        return;
                    };
                    if let Ok(Some(_item)) = crate::from_json::<Option<MessageActionItem>>(
                        lsp_types::ShowMessageRequest::METHOD.as_str(),
                        &result,
                    ) {
                        this.send_notification::<lsp_ext::OpenServerLogsNotification>(());
                    }
                },
            ),
            false => self.send_notification::<lsp_types::ShowMessageNotification>(
                lsp_types::ShowMessageParams { kind, message },
            ),
        }
    }

    /// If `additional_info` is [`Some`], appends a note to the notification telling to check the logs.
    /// This will always log `message` + `additional_info` to the server's error log.
    pub(crate) fn show_and_log_error(&mut self, message: String, additional_info: Option<String>) {
        match additional_info {
            Some(additional_info) => {
                tracing::error!("{message}:\n{additional_info}");
                self.show_message(
                    lsp_types::MessageType::Error,
                    message,
                    tracing::enabled!(tracing::Level::ERROR),
                );
            }
            None => {
                tracing::error!("{message}");
                self.send_notification::<lsp_types::ShowMessageNotification>(
                    lsp_types::ShowMessageParams { kind: lsp_types::MessageType::Error, message },
                );
            }
        }
    }

View on GitHub (pinned to e8f7e90aa3)

Solutions

1. Read the additional info after the colon in the notification and the rust-analyzer output/error log for the root cause.
2. For discovery-related messages, fix the workspace/discovery configuration (linkedProjects, custom discovery command).
3. If it's a developer poke from a source build, it's informational — verify you built correctly (cargo xtask install vs plain cargo build).
4. Reproduce with RUST_LOG=error to capture the full context and file an issue if it's an internal invariant failure.

client.onNotification(lsp.ShowMessageNotification.type, (p) => {
  if (p.type === lsp.MessageType.Error) {
    const [msg, info] = p.message.split(':\n', 2);
    log.error(msg, info ?? 'see rust-analyzer output channel');
  }
});

When it happens

Trigger: Any code path calling GlobalState::show_and_log_error — notably poke_rust_analyzer_developer (developer-build warnings) and project discovery failures (handle_discover_msg) — passing a formatted message and optional extra info.

Common situations: Running a from-source `cargo xtask install`/POKE_RA_DEVS build that warns developers; project/workspace discovery failing so an error is shown with a hint to check logs; other internal components reporting user-visible failures.

Related errors

• Cannot rename builtin type
• cargo check failed to start: {err}
• Project discovery failed: {error}
• We explicitly do not provide canonicalization API, as that i
• bad kind {other}

AI-assisted analysis of rust-lang/rust-analyzer@e8f7e90aa3 (2026-09-03). Data as JSON: /api/errors/a491af593cbfbed3. Report an issue: GitHub.