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Setup Guide
This guide gives a simplified opinionated setup for developers contributing to rust-analyzer using Visual Studio Code to make changes and Visual Studio Code Insiders to test those changes. This guide will assume you have Visual Studio Code and Visual Studio Code Insiders installed.
Prerequisites
Since rust-analyzer is a Rust project, you will need to install Rust. You can download and install the latest stable version of Rust here.
Step-by-Step Setup
Step 01: Fork the rust-analyzer repository and clone the fork to your local machine.
Step 02: Open the project in Visual Studio Code.
Step 03: Open a terminal and run cargo build to build the project.
Step 04: Install the language server locally by running the following command:
cargo xtask install --server --code-bin code-insiders --dev-rel
In the output of this command, there should be a file path provided to the installed binary on your local machine. It should look something like the following output below:
Installing <path-to-rust-analyzer-binary>
Installed package `rust-analyzer v0.0.0 (<path-to-rust-analyzer-binary>)` (executable `rust-analyzer.exe`)
In Visual Studio Code Insiders, you will want to open your User Settings (JSON) from the Command Palette. From there you should ensure that the rust-analyzer.server.path key is set to the <path-to-rust-analyzer-binary>. This will tell Visual Studio Code Insiders to use the locally installed version that you can debug.
The User Settings (JSON) file should contain the following:
{
"rust-analyzer.server.path": "<path-to-rust-analyzer-binary>"
}
Now you should be able to make changes to rust-analyzer in Visual Studio Code and then view the changes in Visual Studio Code Insiders.
Debugging rust-analyzer
The simplest way to debug rust-analyzer is to use the eprintln! macro. The reason why we use eprintln! instead of println! is because the language server uses stdout to send messages. So instead we will debug using stderr.
An example debugging statement could go into the main_loop.rs file which can be found at crates/rust-analyzer/src/main_loop.rs. Inside the main_loop we will add the following eprintln! to test debugging rust-analyzer:
eprintln!("Hello, world!");
Now we run cargo build and sh cargo xtask install --server --code-bin code-insiders --dev-rel to reinstall the server.
Now on Visual Studio Code Insiders, we should be able to open the Output tab on our terminal and switch to Rust Analyzer Language Server to see the eprintln! statement we just wrote.
If you are able to see your output, you now have a complete workflow for debugging rust-analyzer.