Using clap_complete::dynamic::ArgValueCompleter for buck2

[davidbarsky]

Hi! I'm super excited to see dynamic completions happen. A colleague of mine—Ben—implemented some form of buck-driven completions for build target targets. If buck is to move over to clap_complete::dynamic::ArgValueCompleter (as elaborated in the docs added here), would the existing APIs/functionality be sufficient to support a wide variety of shells? I ask because the tracking issue lists direct communication with shells as open issues and I'm not sure if that implies minimal completion scripts are still required or if those tracking issues refer to the removal of user-facing completion scripts entirely.

For example, it'd be nice if the following could be supported in Buck natively:

$ buck2 build - fbcode//buc$0

fbcode//buck2
fbcode//buck_auto_mode
fbcode//buck_targets_info
fbcode//buckedit

(The $0 is the cursor where the user pressed "tab" for completions, the list of target labels starting with fbcode//buck2 are the provided completions)

[epage]

We have initial support for each of our primary shells. The issues are left open because we need to audit for shell-integration parity with the static completions we provide.

That doesn't mean things are perfect. I was planning to add more shell-specific tests to see what holes we have.

Feel free to give it a try and provide feedback! We're about to integrate it into nightly cargo as well.

[davidbarsky]

Wonderful! I think would be possible/reasonable to give it a spin.