Stabilize `-Z avoid-dev-deps` as `--minimal-cargo-lock`

[infinity0]

Original issue: #4988
Implementation: #5012
Documentation: https://doc.rust-lang.org/nightly/cargo/reference/unstable.html#avoid-dev-deps
Issues: Z-avoid-dev-deps Nightly: avoid-dev-deps

-Z avoid-dev-deps flag avoids resolving dev-dependencies in certain targets like install.

@alexcrichton thinks that "in the long run [this wants] to be something like --minimal-cargo-lock which prunes all non-relevant dependencies like platform-specific dependencies that don't apply, dev-deps if you're not building tests, etc."

[matklad]

@infinity0

Clarification question: am I correct that cargo install currently avoids dev dependencies even if the flag is not specified? That is, this issue is specifically for cargo build command?

[infinity0]

@matklad when I last touched that code, yes. the dev_dependencies_no_check test is for this.

[igor-raits]

@infinity0 do you have some patch for this?

We wanted to not package some optional dependencies and hit this issue.

[igor-raits]

\cc @keszybz

[igor-raits]

and also deps for disabled features, I hope. Right?

[infinity0]

@ignatenkobrain Cargo already carries this functionality as cargo build -Z avoid-dev-deps or cargo install (with no extra flags) but only for dev-dependencies, not optional dependencies or unused features or unused target-specific dependencies. No I don't have a patch for the other things I mentioned.

[igor-raits]

@alexcrichton any chance to get someone to work on this? I'm pretty sure that all distributions which decide to package crates will get hit by this.