Dry run option for dvc gc

[fedorn]

Can we have a dry run option for dvc gc so we can see what files and directories the command would delete without actually deleting it?

[efiop]

@fedorn Sure. Contributions are welcome.

[parthvnp]

Happy to work on this one!

[dberenbaum]

Related: https://discord.com/channels/485586884165107732/563406153334128681/1139483806957576212

[christian-steinmeyer]

Just used this for the first time. I was slightly discouraged by the warning message given, when no -f flag is present. Perhaps one could add an additional confirmational hint / don't show this warning, when running with --dry? (Did not open a new issue because it's a minor thing.)

> dvc gc -A --dry
WARNING: This will remove all cache except items used in the workspace and all git commits of the current repo.
Are you sure you want to proceed? [y/n]:

And further down the line, when there are any files found, a similar message is given:

Missing cache for directory <...> Cache for files inside will be lost. Would you like to continue? Use '-f' to force. [y/n]      

[dberenbaum]

Good point @christian-steinmeyer. Opened a PR in #10061 to assume --force when using --dry.