Feature Request: Add fish shell completion support

[liblaf]

Thank you for all your hard work on DVC. It's an incredibly useful tool that has become an essential part of my workflow.

I would like to request the addition of shell completion support for the fish shell.

DVC already has a great dvc completion command that provides completion scripts for bash and zsh. It would be fantastic if fish shell could be added as another supported option. This would allow users of the fish shell to benefit from the same seamless command-line experience as users of other shells.

A possible implementation could be to extend the dvc completion -s command to accept fish as an argument, like so:
dvc completion -s fish > ~/.config/fish/completions/dvc.fish

Thank you for considering this request.

[skshetry]

We depend on shtab to generate completions from the argparse.ArgumentParser. It only supports bash and zsh at the moment.

There is an open feature request and a PR that has gone stale and requires some work for nested command completions (fish does not make that easier either, see fish-shell/fish-shell#7107).

• fish shell support shtab#134
• Supports fish shell shtab#174

Feel free to contribute. If shtab supports it, we'll support it too. :)

[skshetry]

Opened PR upstream:

• supports fish shell - v2 shtab#195.

and in DVC:

• completion: support fish completion #10881

If you can test this out, that'd be great.