List all crates that will be built by `cargo build` in JSON

[yshui]

Problem

IIUC cargo metadata doesn't do feature unification, and can't tell you which crates will actually be built. cargo tree -e normal,build does do that, but it cannot output JSON.

practically parsing the output of cargo tree isn't that bad, but it would be nice if it can output JSON.

has been raised before: sfackler/cargo-tree#21

Proposed Solution

No response

Notes

No response

[epage]

#7754 is our issue for cargo metadata that resolves features for a specific build configuration. It likely won't be solved directly that way.

On https://doc.rust-lang.org/cargo/reference/unstable.html#list-of-unstable-features, we link to an external project as an experiment in what plumbing commands should look like in Cargo moving forward.

Closing in favor of the existing issue and that effort. If there is a reason for us to reevaluate this, let us know!

[weihanglo]

There is also an unstable [--unit-graph] CLI option you can experiment with: https://doc.rust-lang.org/cargo/reference/unstable.html#unit-graph.