rust-ecosystem

name	Rust Ecosystem
description	This skill should be used when working with Rust projects, "Cargo.toml", "rustc", "cargo build/test/run", "clippy", "rustfmt", or Rust language patterns. Provides comprehensive Rust ecosystem patterns and best practices.
version	0.1.0

Provide comprehensive patterns for Rust language, Cargo project management, and toolchain configuration.

<rust_language> <ownership_borrowing> Each value has exactly one owner. When owner goes out of scope, value is dropped. Use move semantics by default; explicit Clone when needed

Immutable and mutable references with strict rules &T allows multiple simultaneous borrows &mut T allows exactly one mutable borrow Cannot have &mut T while &T exists Lifetime annotations for reference validity Compiler infers lifetimes in common patterns Explicit lifetime annotations for complex cases fn foo<'a>(x: &'a str) -> &'a str { x } 'static for values that live entire program Explicit duplication with .clone() Implicit bitwise copy for simple types Debug formatting with {:?} User-facing formatting with {} Default value construction Equality comparison Ordering comparison Hashing for HashMap/HashSet keys Type conversions Cheap reference conversions Automatically implement common traits #[derive(Debug, Clone, PartialEq, Eq, Hash)] struct MyType { field1: String, field2: i32, }

<error_handling> Recoverable errors with Result with T and E type parameters ? for early return on Err map, and_then, unwrap_or, unwrap_or_else

Optional values with Option with T type parameter ? for early return on None map, and_then, unwrap_or, unwrap_or_default Define custom error types with thiserror or anyhow #[derive(Debug, thiserror::Error)] enum MyError { #[error("IO error: {0}")] Io(#[from] std::io::Error), #[error("Parse error: {msg}")] Parse { msg: String }, }

<common_patterns> Fluent API for complex object construction MyStruct::builder() .field1(value1) .field2(value2) .build()

Wrapper type for type safety struct UserId(u64); Encode state in type system Prevent invalid state transitions at compile time

<anti_patterns> Using unwrap() in library code Use ? or proper error handling instead

Cloning values unnecessarily Prefer borrowing when possible Using String for all domain values Use enums, newtypes for domain modeling Defaulting to Arc with Mutex with T for concurrency Consider channels or ownership patterns first . ├── Cargo.lock ├── Cargo.toml ├── src/ │ ├── lib.rs # Library crate root │ ├── main.rs # Binary crate root │ └── bin/ # Additional binaries ├── tests/ # Integration tests ├── benches/ # Benchmarks └── examples/ # Example code

<module_organization> src/module/mod.rs with submodules src/module.rs (preferred for simple modules) </module_organization> </project_structure>

<cargo_toml> <basic_structure> [package] name = "my-crate" version = "0.1.0" edition = "2021" # Current edition; edition 2024 (upcoming/future) rust-version = "1.83" # Current stable as of Dec 2025

[dependencies] serde = { version = "1.0", features = ["derive"] }

[dev-dependencies] tokio-test = "0.4"

[build-dependencies] cc = "1.0" </basic_structure>

<feature_flags> [features] default = ["std"] std = [] async = ["tokio"] full = ["std", "async"] </feature_flags>

<profile_optimization> [profile.release] lto = true codegen-units = 1 panic = "abort" strip = true

[profile.dev] opt-level = 0 debug = true </profile_optimization> </cargo_toml>

[workspace] resolver = "2" # Current default for edition 2021; resolver 3 (upcoming, requires Edition 2024) members = ["crate-a", "crate-b"]

[workspace.package] version = "0.1.0" edition = "2021" license = "MIT"

[workspace.dependencies] serde = "1.0" tokio = { version = "1", features = ["full"] } </root_cargo_toml>

<member_inheritance> [package] name = "crate-a" version.workspace = true edition.workspace = true

[dependencies] serde.workspace = true </member_inheritance>

Compile the project Compile with optimizations Build and run binary Run all tests Fast syntax/type check without codegen Generate and open documentation Update dependencies Display dependency tree Rust linter for catching common mistakes and improving code cargo clippy -- -D warnings In Cargo.toml [lints.clippy] pedantic = "warn" nursery = "warn" unwrap_used = "deny" expect_used = "deny"

<file_reference>Or in clippy.toml</file_reference>

msrv = "1.70" cognitive-complexity-threshold = 25

<common_lints> Prefer ? or proper error handling Prefer ? or proper error handling Stricter lints for cleaner code Experimental but useful lints </common_lints>

Automatic code formatter cargo fmt rustfmt.toml edition = "2021" max_width = 100 use_small_heuristics = "Max" imports_granularity = "Crate" group_imports = "StdExternalCrate" reorder_imports = true

<cargo_nextest> Next-generation test runner with better output and parallelism cargo nextest run

Parallel test execution Better failure output JUnit XML output for CI Test retries .config/nextest.toml [profile.default] retries = 2 slow-timeout = { period = "60s", terminate-after = 2 } fail-fast = false

<other_tools> Security vulnerability scanning Dependency license and security checks Check for outdated dependencies Auto-rebuild on file changes Macro expansion debugging </other_tools>

<context7_integration> Use Context7 MCP for up-to-date Rust documentation

<rust_libraries> </rust_libraries>

<usage_patterns> resolve-library-id libraryName="rust lang" get-library-docs context7CompatibleLibraryID="/rust-lang/book" topic="ownership"

get-library-docs context7CompatibleLibraryID="/rust-lang/cargo.git" topic="workspace" get-library-docs context7CompatibleLibraryID="/rust-lang/rust-clippy" topic="lints configuration"

<best_practices> Use cargo check for fast iteration during development Run cargo clippy before committing Format with cargo fmt for consistent style Use workspace for multi-crate projects Prefer &str over String for function parameters Use impl Trait for return types when possible Document public API with /// doc comments Write unit tests alongside code in same file Use integration tests in tests/ for API testing Set rust-version in Cargo.toml for MSRV </best_practices>