Panic Strategies & Binary Size

panic = "unwind" (default)

• Runs destructors when panicking
• Supports catch_unwind
• Larger binary (unwinding tables)
• Slower panics

panic = "abort"

• Program terminates immediately
• No destructors run
• Smaller binary
• Faster panics (they're rare anyway)

toml
[profile.release]
panic = "abort"

When to Use Each

Binary Size Reduction

toml
[profile.release]
panic = "abort"         # Remove unwinding
strip = true            # Remove symbols
opt-level = "z"         # Size optimization
lto = true              # Dead code elimination
codegen-units = 1       # Better DCE

More Techniques

bash
# Use cargo-bloat to find what's taking space
cargo install cargo-bloat
cargo bloat --release

# Strip after build
strip target/release/myapp

# UPX compression (controversial)
upx --best target/release/myapp

std vs no_std

rust
// Smallest possible binary (no std)
#![no_std]
#![no_main]

#[panic_handler]
fn panic(_: &core::panic::PanicInfo) -> ! {
    loop {}
}

// Using catch_unwind (requires panic="unwind")
use std::panic;

fn might_panic() {
    panic!("oops!");
}

fn main() {
    let result = panic::catch_unwind(|| {
        might_panic();
    });
    
    match result {
        Ok(()) => println!("No panic"),
        Err(_) => println!("Caught a panic!"),
    }
    
    println!("Program continues...");
}

// Note: catch_unwind is NOT for normal error handling!
// Use it for:
// - FFI boundaries (don't let panics cross into C)
// - Thread pools (don't crash the whole pool)
// - Plugin systems