rust-binary-size

name	rust-binary-size
description	Guides Rust binary size reduction for ccusage. Use when changing the rust/Cargo.toml release profile, dependency features, native packaging size, or investigating executable bloat with cargo bloat.
paths	["rust/Cargo.toml","rust/**/*.rs","rust/**/*.toml","apps/ccusage/scripts/**"]
globs	rust/**/*.rs,rust/**/*.toml,apps/ccusage/scripts/**

Rust Binary Size

https://github.com/johnthagen/min-sized-rust

Baseline

[profile.release] in rust/Cargo.toml already applies the min-sized-rust settings, including a separate opt-level for dependencies. Read it before adding anything, and change it only when a measurement argues for it.

What ends up in a published platform package is the single bin/ccusage staged by the Nushell scripts in apps/ccusage/scripts/, so packaged size tracks the binary almost exactly. The development skill covers that packaging seam.

Investigation

Measure before editing code or dependencies:

direnv exec . cargo build --manifest-path rust/Cargo.toml --release --bin ccusage
ls -lh rust/target/release/ccusage

When the release profile does not explain a regression, look at feature flags (cargo tree -e features -p ccusage) and large symbols (cargo bloat --release --bin ccusage --crates), both against the same manifest. cargo bloat is not in the dev shell; the missing-tools skill covers running it without a flake change.

Change Ordering

Low-risk first: drop unnecessary dependency default features once tests show they are unused, narrow optional features rather than swapping a well-fitting crate, and remove dead release-only code paths or assets. CLI behavior, JSON output, table output, and packaging semantics stay unchanged unless the user asks otherwise.

These are opt-in experiments, appropriate only when the user asks for an aggressive minimum-size push: nightly-only flags (-Zlocation-detail, -Zfmt-debug, panic=immediate-abort, build-std), #![no_std]/#![no_main] with manual stdio, binary packers such as UPX, and prefer-dynamic linking.

Validation

For release-profile or packaging changes, rebuild the native CLI, compare against the earlier measurement, and record the command and result in the PR body or review reply. Repo-wide format and test recipes are in the development skill.