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OpenIDEA uses rust-analyzer for Rust code intelligence, runs and tests crates with cargo, and debugs them with CodeLLDB. Cargo workspaces are supported. For other languages, see the support matrix.

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Language server

rust-analyzer serves .rs files. A workspace starts at the nearest Cargo.toml or rust-project.json. While rust-analyzer is still loading a project, it has no answers for navigation yet. OpenIDEA waits for it instead of reporting “not found”: Declaration or Usages (⌘B / Ctrl+B) right after opening a project lands once the server is ready, for up to 30 seconds. Diagnostics come from rust-analyzer’s own analysis and from cargo check (or Clippy) after each save.

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Installing rust-analyzer

If rust-analyzer is missing, OpenIDEA shows a rust-analyzer is not installed notification with an Install button. You can also install it, or select your own binary, in Settings › Languages & Frameworks › Language Servers.
  • With rustup on PATH, the IDE runs rustup component add rust-analyzer.
  • Without rustup, it downloads the rust-analyzer build from Open VSX into its own tools folder.
~/.cargo/bin/rust-analyzer is a rustup proxy that fails when the active toolchain lacks the component. In that case the IDE uses the newest installed toolchain that has rust-analyzer; if none has it, the server counts as missing and you get the install offer.

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Setup

Settings › Languages & Frameworks › Rust has these options: Reformat Code (⌘⌥L / Ctrl+Alt+L) formats with rustfmt through rust-analyzer. Crates and the Rust standard library appear under External Libraries in the Project view.

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Run and test

OpenIDEA reads Cargo.toml (and the members of a [workspace]) and detects: In the editor, gutter icons run or debug:
  • fn main in src/main.rs, src/bin/*.rs and examples/*.rs,
  • functions marked #[test], #[tokio::test], #[async_std::test], #[actix_rt::test], #[rstest] or #[test_case],
  • mod tests and modules marked #[cfg(test)], which run every test inside.
A single test runs as cargo test -- <path> --exact. Results appear in the test tree; Rerun Failed Tests runs only the failures. See Run configurations and Testing. Build Project runs cargo build --all-targets, Rebuild Project runs cargo clean first, and Build Artifacts runs cargo build --release. Compiler messages go to the Build tool window and the editor. Run with Coverage uses cargo llvm-cov for cargo test, cargo run and cargo nextest configurations. If it is missing, the IDE offers cargo install cargo-llvm-cov (the llvm-tools-preview rustup component is needed too). See Coverage.

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Debugging

Rust debugging uses CodeLLDB. If it is missing when you start a debug session, OpenIDEA offers to install it; it downloads the CodeLLDB release from GitHub into its tools folder. The cargo run and test configurations and the gutter icons can be debugged: CodeLLDB builds the target with cargo and starts the resulting binary. Attach to Process… (⌥⇧F5 / Ctrl+Alt+F5) lists native processes under Native (LLDB). See Debugging.

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Limitations

  • CodeLLDB publishes no Windows ARM64 build, so the IDE cannot install it there.
  • rust-analyzer’s own extension commands, such as Expand Macro or View Syntax Tree, are not available as IDE actions.
  • The profiler supports cargo run only on Linux (with perf). See Profiler.