23.5 Building and Running Projects
As described earlier, the cargo build and cargo run commands—optionally with the --release flag—are used to compile a project, and in the case of run, also execute it. By default, these commands operate in debug mode, but adding --release enables performance optimizations.
23.5.1 Incremental Builds
Cargo uses incremental compilation in debug mode to speed up rebuilds. When you modify only one source file, Cargo recompiles just that file and any dependents, significantly reducing build times for large projects.
Incremental compilation applies only to the current crate, not to external dependencies.
Cargo also caches compiled dependencies—external crates listed in Cargo.toml—and reuses them across builds as long as they remain unchanged. This prevents unnecessary recompilation of stable external code, further accelerating the build process.
23.5.2 cargo check
For even faster feedback, cargo check parses and type-checks your code without fully compiling it:
cargo check
cargo check benefits from incremental compilation and dependency caching, but skips generating an executable. It’s ideal for catching compiler errors quickly during development.