Troubleshooting

First, search the troubleshooting FAQ. If your problem appears there (and the proposed solution works for you), great! Otherwise, read on.

Start with looking at the rust-analyzer version. Try rust-analyzer: Show RA Version in VS Code (using Command Palette feature typically activated by Ctrl+Shift+P) or rust-analyzer --version in the command line. If the date is more than a week ago, it’s better to update rust-analyzer version.

The next thing to check would be panic messages in rust-analyzer’s log. Log messages are printed to stderr, in VS Code you can see them in the Output > Rust Analyzer Language Server tab of the panel. To see more logs, set the RA_LOG=info environment variable, this can be done either by setting the environment variable manually or by using rust-analyzer.server.extraEnv, note that both of these approaches require the server to be restarted.

To fully capture LSP messages between the editor and the server, run the rust-analyzer: Toggle LSP Logs command and check Output > Rust Analyzer Language Server Trace.

The root cause for many "nothing works" problems is that rust-analyzer fails to understand the project structure. To debug that, first note the rust-analyzer section in the status bar. If it has an error icon and red, that’s the problem (hover will have somewhat helpful error message). rust-analyzer: Status prints dependency information for the current file. Finally, RA_LOG=project_model=debug enables verbose logs during project loading.

If rust-analyzer outright crashes, try running rust-analyzer analysis-stats /path/to/project/directory/ on the command line. This command type checks the whole project in batch mode bypassing LSP machinery.

When filing issues, it is useful (but not necessary) to try to minimize examples. An ideal bug reproduction looks like this:

git clone https://github.com/username/repo.git && cd repo && git switch --detach commit-hash
rust-analyzer --version
rust-analyzer dd12184e4 2021-05-08 dev
rust-analyzer analysis-stats .

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It is especially useful when the repo doesn’t use external crates or the standard library.

If you want to go as far as to modify the source code to debug the problem, be sure to take a look at the contribution guide!