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cargo why <crate> #10006
Description
Problem
It is hard to know why a specific crate is required (and why it has a specific version).
Proposed Solution
There could be a sub command named why that could display the constraints applied to a crate and the dependency tree linked to it in order to understand why a specific crate is required.
Composer (PHP's package manager) exposes such sub command: https://getcomposer.org/doc/03-cli.md#depends-why-
Notes
This issue should be flagged with A-new-subcommand I guess.
A "similar" issue exists #1211 but it does not have the same intent
Activity
[-]`cargo why <crate>` package[/-][+]`cargo why <crate>`[/+]weihanglo commentedon Nov 10, 2021
cargo-treecovers some usages here. For example. runcargo tree -i curlshows the reversed dependency tree:The tree command also supports showing enabled features for dependencies. But unfortunately, it doesn't cover "why it has a specific version" as you mentioned.
homersimpsons commentedon Nov 11, 2021
Oh, I didn't notice that you could invert
cargo-tree. Thank you for this information !epage commentedon Apr 20, 2022
Since we have
cargo tree -i, do we still need this issue? Is there something we could do to make it easier to go from user problem ("why this dependency") to discoveringcargo tree -i?Granted, for myself, I just use
cargo tree | lessand just search the output because I forget about-i(speaking of, maybe we should have pager support forcargo tree).epage commentedon Oct 31, 2023
Closing this as covered by
cargo tree. #12903 adds some more documentation around this.