cargo install --release gives a confusing error

[jyn514]

Problem

I have a friend who doesn't know rust and tried to install a program written in Rust. First he tried cargo build and that ran too slowly, so I told him to use --release. Then he tested it to his satisfaction and tried to install it:

$ cargo install --release --path . --locked
error: unexpected argument '--release' found

  note: argument '--examples' exists

Usage: cargo install --examples [crate]...

For more information, try '--help'.

The problem here is that the defaults are flipped between build and install: build defaults to the dev profile and has a --release flag, install defaults to the release profile and has a --debug flag. That seems ok, but the error message is unhelpful.

Proposed Solution

Improve the error message:

$ cargo install --release --path . --locked
error: unexpected argument '--release' found

  note: `install` uses the release profile by default
  help: remove `--release` to install using the release profile: `cargo install --path . --locked`

Usage: cargo install [OPTIONS] [crate]...

For more information, try '--help'.

Notes

Don't remember when this happened originally, but the error messages in the issue description came from cargo 1.68.2 (6feb7c9cf 2023-03-26).

[jyn514]

It probably makes sense to do the same for cargo build --debug, which gives a similarly unhelpful error currently:

$ cargo build --debug
error: unexpected argument '--debug' found

Usage: cargo build [OPTIONS]

For more information, try '--help'.

[epage]

clap-rs/clap#4706 would be useful for this

[weihanglo]

#11702 wants exactly the same feature. Close this as it seems to be a duplicate. I'll add this case to the list there.