Support the -- separator, e.g. `git log -- dir/`

[mytskine]

Request

A common pattern is to use -- to separate flags from other arguments, usually paths. It's a default behaviour for many programs, and libraries like getopt.

Proposed solution

From the top of my head, some commands that would benefit from this pattern:

• git status -- some/dir<TAB> (same with diff, log, and many other commands)
• bash -x -- .local/<TAB>
• tree -d -- /etc/ng<TAB>

Anything else?

I could not find any completion that implements this. I tried to write one myself, but it seems that a -- argument breaks the parsing of carapace. In my tests, the callback passed to PositionalAnyCompletion() was never called for arguments after --. Unless I'm mistaken, the carapace API does not document this nor provide an alternative. I did not dig any further, so I may haved missed obvious solutions.

[rsteube]

Carapace has support for this with DashCompletion and DashAnyCompletion.

I went back and forth to support this implicitly but commands vary too much.
So at least for now it has to be configured explicitly and probably is just not added yet.

To continue the existing positional completion there is ActionPositional (ok, this one has no doc yet =D).

carapace.Gen(blameCmd).DashAnyCompletion(
	carapace.ActionPositional(blameCmd),
)

Not entirely happy with this though so it might change a bit in the future.

Git is quite complex so there are also a couple of opiniated choices that were made.
E.g. to separate files from ref arguments (which can be a lot) they are only completed when a path prefix is present (like ./<TAB>).

[rsteube]

Oh and dash completion in carapace resets Context.Args.
So command pos1 pos2 -- pos3 pos4 <TAB> gets [pos3, pos4].
The complete arguments can still be accessed from the flagset thoug (which is what ActionPositional is doing).

The reason for this is that this way Actions can be used for dash just as they are for positonal completion.