72e229fcb3
RUST_LOG might be set up for debugging the user's problem, slowing down rust-analyzer considerably. That's the same reason why rustc uses RUSTC_LOG.
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8.1 KiB
Markdown
192 lines
8.1 KiB
Markdown
# Contributing Quick Start
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Rust Analyzer is just a usual rust project, which is organized as a Cargo
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workspace, builds on stable and doesn't depend on C libraries. So, just
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```
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$ cargo test
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```
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should be enough to get you started!
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To learn more about how rust-analyzer works, see
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[./architecture.md](./architecture.md) document.
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We also publish rustdoc docs to pages:
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https://rust-analyzer.github.io/rust-analyzer/ra_ide/
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Various organizational and process issues are discussed in this document.
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# Getting in Touch
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Rust Analyzer is a part of [RLS-2.0 working
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group](https://github.com/rust-lang/compiler-team/tree/6a769c13656c0a6959ebc09e7b1f7c09b86fb9c0/working-groups/rls-2.0).
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Discussion happens in this Zulip stream:
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https://rust-lang.zulipchat.com/#narrow/stream/185405-t-compiler.2Fwg-rls-2.2E0
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# Issue Labels
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* [good-first-issue](https://github.com/rust-analyzer/rust-analyzer/labels/good%20first%20issue)
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are good issues to get into the project.
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* [E-mentor](https://github.com/rust-analyzer/rust-analyzer/issues?q=is%3Aopen+is%3Aissue+label%3AE-mentor)
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issues have links to the code in question and tests.
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* [E-easy](https://github.com/rust-analyzer/rust-analyzer/issues?q=is%3Aopen+is%3Aissue+label%3AE-easy),
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[E-medium](https://github.com/rust-analyzer/rust-analyzer/issues?q=is%3Aopen+is%3Aissue+label%3AE-medium),
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[E-hard](https://github.com/rust-analyzer/rust-analyzer/issues?q=is%3Aopen+is%3Aissue+label%3AE-hard),
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labels are *estimates* for how hard would be to write a fix.
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* [fun](https://github.com/rust-analyzer/rust-analyzer/issues?q=is%3Aopen+is%3Aissue+label%3Afun)
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is for cool, but probably hard stuff.
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# CI
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We use GitHub Actions for CI. Most of the things, including formatting, are checked by
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`cargo test` so, if `cargo test` passes locally, that's a good sign that CI will
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be green as well. The only exception is that some long-running tests are skipped locally by default.
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Use `env RUN_SLOW_TESTS=1 cargo test` to run the full suite.
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We use bors-ng to enforce the [not rocket science](https://graydon2.dreamwidth.org/1597.html) rule.
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You can run `cargo xtask install-pre-commit-hook` to install git-hook to run rustfmt on commit.
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# Code organization
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All Rust code lives in the `crates` top-level directory, and is organized as a
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single Cargo workspace. The `editors` top-level directory contains code for
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integrating with editors. Currently, it contains the plugin for VS Code (in
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typescript). The `docs` top-level directory contains both developer and user
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documentation.
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We have some automation infra in Rust in the `xtask` package. It contains
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stuff like formatting checking, code generation and powers `cargo xtask install`.
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The latter syntax is achieved with the help of cargo aliases (see `.cargo`
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directory).
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# Launching rust-analyzer
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Debugging language server can be tricky: LSP is rather chatty, so driving it
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from the command line is not really feasible, driving it via VS Code requires
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interacting with two processes.
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For this reason, the best way to see how rust-analyzer works is to find a
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relevant test and execute it (VS Code includes an action for running a single
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test).
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However, launching a VS Code instance with locally build language server is
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possible. There's **"Run Extension (Dev Server)"** launch configuration for this.
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In general, I use one of the following workflows for fixing bugs and
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implementing features.
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If the problem concerns only internal parts of rust-analyzer (ie, I don't need
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to touch `rust-analyzer` crate or typescript code), there is a unit-test for it.
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So, I use **Rust Analyzer: Run** action in VS Code to run this single test, and
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then just do printf-driven development/debugging. As a sanity check after I'm
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done, I use `cargo xtask install --server` and **Reload Window** action in VS
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Code to sanity check that the thing works as I expect.
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If the problem concerns only the VS Code extension, I use **Run Extension**
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launch configuration from `launch.json`. Notably, this uses the usual
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`rust-analyzer` binary from `PATH`. For this it is important to have the following
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in `setting.json` file:
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```json
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{
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"rust-analyzer.serverPath": "rust-analyzer"
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}
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```
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After I am done with the fix, I use `cargo
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xtask install --client-code` to try the new extension for real.
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If I need to fix something in the `rust-analyzer` crate, I feel sad because it's
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on the boundary between the two processes, and working there is slow. I usually
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just `cargo xtask install --server` and poke changes from my live environment.
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Note that this uses `--release`, which is usually faster overall, because
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loading stdlib into debug version of rust-analyzer takes a lot of time. To speed
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things up, sometimes I open a temporary hello-world project which has
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`"rust-analyzer.withSysroot": false` in `.code/settings.json`. This flag causes
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rust-analyzer to skip loading the sysroot, which greatly reduces the amount of
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things rust-analyzer needs to do, and makes printf's more useful. Note that you
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should only use `eprint!` family of macros for debugging: stdout is used for LSP
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communication, and `print!` would break it.
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If I need to fix something simultaneously in the server and in the client, I
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feel even more sad. I don't have a specific workflow for this case.
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Additionally, I use `cargo run --release -p rust-analyzer -- analysis-stats
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path/to/some/rust/crate` to run a batch analysis. This is primarily useful for
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performance optimizations, or for bug minimization.
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# Logging
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Logging is done by both rust-analyzer and VS Code, so it might be tricky to
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figure out where logs go.
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Inside rust-analyzer, we use the standard `log` crate for logging, and
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`env_logger` for logging frontend. By default, log goes to stderr, but the
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stderr itself is processed by VS Code.
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To see stderr in the running VS Code instance, go to the "Output" tab of the
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panel and select `rust-analyzer`. This shows `eprintln!` as well. Note that
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`stdout` is used for the actual protocol, so `println!` will break things.
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To log all communication between the server and the client, there are two choices:
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* you can log on the server side, by running something like
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```
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env RA_LOG=gen_lsp_server=trace code .
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```
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* you can log on the client side, by enabling `"rust-analyzer.trace.server":
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"verbose"` workspace setting. These logs are shown in a separate tab in the
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output and could be used with LSP inspector. Kudos to
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[@DJMcNab](https://github.com/DJMcNab) for setting this awesome infra up!
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There's also two VS Code commands which might be of interest:
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* `Rust Analyzer: Status` shows some memory-usage statistics. To take full
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advantage of it, you need to compile rust-analyzer with jemalloc support:
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```
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$ cargo install --path crates/rust-analyzer --force --features jemalloc
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```
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There's an alias for this: `cargo xtask install --server --jemalloc`.
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* `Rust Analyzer: Syntax Tree` shows syntax tree of the current file/selection.
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You can hover over syntax nodes in the opened text file to see the appropriate
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rust code that it refers to and the rust editor will also highlight the proper
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text range.
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If you press <kbd>Ctrl</kbd> (i.e. trigger goto definition) in the inspected
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Rust source file the syntax tree read-only editor should scroll to and select the
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appropriate syntax node token.
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# Profiling
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We have a built-in hierarchical profiler, you can enable it by using `RA_PROFILE` env-var:
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```
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RA_PROFILE=* // dump everything
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RA_PROFILE=foo|bar|baz // enabled only selected entries
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RA_PROFILE=*@3>10 // dump everything, up to depth 3, if it takes more than 10 ms
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```
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In particular, I have `export RA_PROFILE='*>10'` in my shell profile.
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To measure time for from-scratch analysis, use something like this:
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```
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$ cargo run --release -p rust-analyzer -- analysis-stats ../chalk/
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```
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For measuring time of incremental analysis, use either of these:
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```
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$ cargo run --release -p rust-analyzer -- analysis-bench ../chalk/ --highlight ../chalk/chalk-engine/src/logic.rs
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$ cargo run --release -p rust-analyzer -- analysis-bench ../chalk/ --complete ../chalk/chalk-engine/src/logic.rs:94:0
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```
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