Profiles

When you run cargo build, cargo build --release, or cargo test, cargo uses profiles to determine individual settings for each stage. While these have reasonable defaults, you might want to customize some settings. The manifest provides these switches with the [profile.dev], [profile.release], [profile.test], and [profile.bench] sections:

[profile.release] 
opt-level = 3 
debug = false 
rpath = false 
lto = false 
debug-assertions = false 
codegen-units = 16 
panic = 'unwind' 
incremental = false 
overflow-checks = false

These values are the defaults (as of writing this book) and are already useful for most users.