Rust Cargo Mastery

Comprehensive guide to Cargo based on The Cargo Book.

When to Use This Skill

• Setting up new Rust projects
• Managing dependencies from crates.io
• Configuring build profiles and features
• Working with Cargo workspaces
• Publishing crates to crates.io
• Optimizing build times
• Understanding Cargo's resolution algorithm

Core References

• The Cargo Book - Full Cargo documentation
• Cargo Manifest - Cargo.toml reference

Dependencies

Specifying Dependencies

[dependencies]
serde = "1.0"           # Exact or semver range
regex = "1.5"            # Minor version compatible
anyhow = "1.0"          # Any 1.x version
rand = { version = "0.8", features = ["small_rng"] }

[dev-dependencies]
criterion = "0.5"

Version Syntax

External Dependencies

[dependencies]
log = "0.4"
env_logger = { path = "../env_logger" }
my_crate = { git = "https://github.com/user/repo" }

Workspaces

Basic Workspace

# Cargo.toml (workspace root)
[workspace]
members = ["crate_a", "crate_b"]
resolver = "2"

[workspace.package]
version = "1.0.0"
edition = "2021"

[workspace.dependencies]
serde = "1.0"

# crate_a/Cargo.toml
[package]
name = "crate_a"
version.workspace = true
edition.workspace = true

[dependencies]
serde = { workspace = true }

Workspace Features

[workspace]
members = ["lib", "binary"]

[workspace.dependencies]
my_lib = { path = "lib", default-features = false }

Features

Defining Features

[features]
default = ["std"]
std = []
derive = ["serde/derive"]
experimental = []

Feature Unification

Workspace dependencies use unified features:

[dependencies]
common = { path = "../common", features = ["derive"] }
# Uses common's "derive" feature automatically

Conditional Compilation

#[cfg(feature = "experimental")]
fn experimental_api() {}

#[cfg(not(feature = "std"))]
fn no_std_compatible() {}

Build Profiles

Custom Profiles

[profile.dev]
opt-level = 0
debug = true
split-debuginfo = "unpacked"

[profile.release]
opt-level = 3
lto = "thin"
codegen-units = 1

[profile.bench]
inherits = "release"

Profile Override

[profile.dev.package."*"]
opt-level = 2

Publishing

Publishing to crates.io

cargo login
cargo publish

Package Metadata

[package]
name = "my_crate"
version = "1.0.0"
edition = "2021"
description = "A short description"
license = "MIT"
license-file = "LICENSE"
repository = "https://github.com/user/repo"
documentation = "https://docs.rs/my_crate/"
homepage = "https://mycrate.io"
keywords = ["tag1", "tag2"]
categories = ["category1", "category2"]

[package.metadata.docs.rs]
all-features = true
rustdoc-args = ["--cfg", "docsrs"]

Reference Map

• references/dependencies.md - Dependency specification, versions
• references/workspaces.md - Workspace configuration
• references/features.md - Feature flags, conditional compilation
• references/profiles.md - Build profiles, optimization
• references/publishing.md - Publishing to crates.io

Common Commands

cargo new project_name
cargo build
cargo run
cargo test
cargo check
cargo doc
cargo publish
cargo update
cargo tree
cargo clippy

Key References

• The Cargo Book
• Cargo Reference