Reference — Rust Toolchain Commands

Daily loop

Command	What it does
`cargo check`	Your default. Type-checks and borrow-checks without producing a binary. Several times faster than `build`. Use this while fighting the compiler.
`cargo run`	Builds if needed, then runs. Debug profile — slow binary, fast compile.
`cargo run --release`	Optimised. Slow to compile, ~10–100× faster at runtime. Use only when measuring performance or shipping — a debug-build editor will feel sluggish on big files and that is not a real bug.
`cargo build`	Compiles to `target/debug/editor` without running.
`cargo test`	Runs every `#[test]` function in the crate.

Code quality — matters for a portfolio repo

Command	What it does
`cargo fmt`	Formats every file to the community standard. No configuration, no debate. Run before every commit.
`cargo clippy`	831 lints for non-idiomatic Rust. This is the closest thing to having a senior Rust dev review your code, and a reviewer will notice if you haven't run it.
`cargo clippy --fix`	Applies the mechanical fixes automatically.
`cargo doc --open`	Builds docs for your crate and every dependency, at the exact versions you're using, then opens them. Offline and always correct — better than docs.rs.

Dependencies

Command	What it does
`cargo add crate`	Adds a dependency to `Cargo.toml` at the latest compatible version.
`cargo add crate --features x`	Adds it with optional features enabled.
`cargo remove crate`	Removes it.
`cargo update`	Bumps `Cargo.lock` within the version ranges in `Cargo.toml`.
`cargo tree`	Prints the full dependency graph. Useful for "why do I have three versions of this?"

Cargo.toml vs Cargo.lockCargo.toml is what you asked for (eframe = "0.36.1", meaning "0.36.1 or any compatible later version"). Cargo.lock is what yougot — exact versions of all 414 crates. Commit both for a binary; the lockfile is what makes a reviewer's cargo run reproduce your build exactly.

rustup — managing Rust itself

Command	What it does
`rustup update`	Updates to the latest stable Rust. Safe — Rust takes backwards compatibility seriously.
`rustup show`	Which toolchains are installed and which is active.
`rustup doc`	Opens the entire offline Rust documentation set, including the book.
`rustup component add rust-analyzer`	The language server — autocomplete, inline types, jump-to-definition in your editor.
`source ~/.cargo/env`	Fixes "command not found: cargo" in a shell that didn't pick up the PATH.

This machine specificallyFedora-based atomic desktop. Rust lives in ~/.cargo and~/.rustup, installed by rustup. Do notrpm-ostree install rust — layering a toolchain onto the base image gets you an older compiler and a rebase headache. rustup in $HOME is the right answer here, and it uninstalls cleanly with rustup self uninstall.

Reading a compiler error

Rust errors have a fixed shape. Learn it once and they stop being walls of text:

error[E0502]: cannot borrow `self.text` as mutable ...
  --> src/main.rs:22:17          <- file:line:column
   |
22 |     ui.add(TextEdit::multiline(&mut self.text))
   |                                 ^^^^^^^^^^^^^^  <- the exact span
   |
   = help: consider changing this to be mutable   <- usually correct

Read the last line first. The help: ornote: at the bottom is frequently the literal fix.
Fix the first error only, then re-check. One real error often cascades into ten fake ones.
rustc --explain E0502 gives a full page on any error code, with examples. There is one for every code.