This allows two overriding args to interact with each other mid-line.
This was broken in 7673dfc / #1154. Before that, we duplicated the override
logic in several places.
Now we plug into the start of a new arg which allows us to do this
incrementally without making the logic complex or inefficient, thanks to
prior refactors.
Fixes#3217
This will have a slight performance hit as `AllArgsOverrideSelf` will
allocate a single-element `Vec` per `Arg`. This can be lessened for
positional and multiple occurrences by shifting those checks up into the
propagation check.
Long term, I'd like to see all of the `Arg`-in-`App` settings switch to
this which will make it easier for callers, like completions and man
pages, to figure out whats going on without duplicating the logic.
Short term, this is motivated by wanting to change the override logic to
accomodated interleaved overrides from #3217. Moving this logic will
make it easier to change the override logic.
This is the logical order people think in terms of (`--foo` comes before
`val` in `--foo val`). This also opens things up for using occurrence
incrementing as a place to handle occurrence transitions, like
overrides.
This makes some naming more explicit and allows us to increment
occurrences before adding values (which is the logical mental order and
allows other improvements).
We were storing data off into the struct, obscuring the direct
relationship between gathering and validating conflicts.
With this, not as much code needs to deal with mutable data
And other derive tweaks. I'm mixed on how far to go, including
- Linking to the derive reference
- Showing how to use each trait with both the derive and builder APIs
For now, this is an improvement.
Confirmed this works with [`argfile`](https://docs.rs/argfile/latest/argfile/)
And then running in clap
```
$ RUSTDOCFLAGS="--cfg docsrs" cargo +nightly doc --all-features
```
They now show up!
While I'm unsure how much type specialization we should do, we
intentionally have the `arg_enum` attribute for doing special behavior
based on it, so let's take advantage of it.
Fixes#3185
