Rust Compiler Skill

This skill optimizes Rust compilation workflows to minimize token consumption while maintaining full visibility into errors and warnings.

Core Principle

For most development tasks use the rust lsp (rust-analyzer) for real-time feedback. When you need to compile or run tests, use the following patterns to capture only relevant output while discarding verbose messages. Rust compiler output can be extremely verbose, especially for successful builds or when downloading dependencies. Redirect stdout to /dev/null while preserving stderr for actual errors and warnings.

Essential Commands

Compilation Check (Fastest Feedback)

cargo check 2>&1 >/dev/null | head -100

Use cargo check instead of cargo build when you only need to verify code compiles. It skips code generation and is significantly faster.

Building Code

cargo build 2>&1 >/dev/null | head -100

For release builds:

cargo build --release 2>&1 >/dev/null | head -100

Clippy Linting

cargo clippy 2>&1 >/dev/null | head -100

Always run clippy after making changes. All warnings must be addressed.

Running Tests

cargo test 2>&1 >/dev/null | head -150

For a specific test:

cargo test test_name 2>&1 >/dev/null | head -100

For a specific crate in a workspace:

cargo test -p crate-name 2>&1 >/dev/null | head -100

Formatting

cargo fmt --all

Always run after editing Rust files. No output redirection needed as it produces minimal output.

Workspace-Specific Commands

For large workspaces, target specific crates to reduce compilation scope:

# Check a specific crate
cargo check -p crate-name 2>&1 >/dev/null | head -100

# Build a specific binary
cargo build --bin binary-name 2>&1 >/dev/null | head -100

# Run clippy on a specific crate
cargo clippy -p crate-name 2>&1 >/dev/null | head -100

Error Investigation

When errors occur, you may need more context. Use these patterns:

# Get more error lines if truncated
cargo check 2>&1 >/dev/null | head -200

# See full error for a specific issue
cargo check 2>&1 >/dev/null | grep -A 20 "error\[E"

# Count total errors
cargo check 2>&1 >/dev/null | grep -c "^error"

Recommended Workflow

1. After writing/editing code: Run cargo fmt --all
2. Quick validation: Run cargo check -p <crate> 2>&1 >/dev/null | head -100
3. Before committing: Run cargo clippy 2>&1 >/dev/null | head -100
4. For tests: Run cargo test -p <crate> 2>&1 >/dev/null | head -150

Why Truncate Output?

• Successful cargo builds can produce thousands of lines of "Compiling..." messages
• Downloading dependencies generates extensive output
• Using head -100 or head -150 captures errors while avoiding token bloat
• The pattern 2>&1 >/dev/null redirects stderr to the pipe while discarding stdout, ensuring only errors and warnings are captured