Add command to explain constraints for a dependency

[Zekfad]

There is a yarn why command in JS package manager Yarn that shows why project depends on a given package.
This is very helpful for exploring transitive dependencies.

In Dart there is dart pub outdated/flutter pub outdated which shows outdated packages, but there are no details for why any given package cannot be updated to latest.

It would be great to add a command that would explain dependency constraints, similar to how there is an error if you have unfeasible constraints during dart pub get.

Such a command would show all constraints (including transitive) applied to a given dependency.

[sigurdm]

Yeah - I think I once started implementing something like pub deps find that would show an import path to a given package. I don't remember why it went nowhere. It seems very useful.

[kevmoo]

@Zekfad – this might help in the meantime: https://pub.dev/packages/pubviz