Pin your Rust toolchain version by creating a rust-toolchain.toml file with the desired channel and components.
Create a rust-toolchain.toml file in your project root to pin the Rust toolchain version for all developers and CI environments. This file overrides the default toolchain and ensures everyone uses the same compiler version.
[toolchain]
channel = "1.90"
components = ["rust-docs"]
When you run cargo build or rustup, it will automatically install and switch to Rust 1.90 with the rust-docs component if it isn't already installed.
The rust-toolchain.toml file tells your computer exactly which version of the Rust compiler to use for this specific project. It works like a recipe card that ensures every developer and every automated test uses the same ingredients, preventing errors caused by version differences. Without it, one person might use a new version while another uses an old one, leading to confusing bugs.