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That's probably because there is no --release flag: $ rustc --release prog.rs error: Unrecognized option: 'release'. There is a -O for optimization, i

That's probably because there is no --release flag: $ rustc --release prog.rs error: Unrecognized option: 'release'. There is a -O for optimization, it is equivalent to -C opt-level=2. EDIT: Oh, cargo build does have a --release which seems to be equivalent to -C opt-level=3, which I guess is even better.

steveklabnik 12y ago
`cargo build --release` does more than just `-C opt-level=3`, actually. For example a regular `cargo build` also adds `-g`, and that's removed for `--release`.