Before #2005, `Clap` was a special trait that derived all clap traits it
detected were relevant (including an enum getting both `ArgEnum`,
`Clap`, and `Subcommand`). Now, we have elevated `Clap`, `Args`,
`Subcommand`, and `ArgEnum` to be user facing but the name `Clap` isn't
very descriptive.
This also helps further clarify the relationships so a crate providing
an item to be `#[clap(flatten)]` or `#[clap(subcommand)]` is more likely
to choose the needed trait to derive.
Also, my proposed fix fo #2785 includes making `App` attributes almost
exclusively for `Clap`. Clarifying the names/roles will help
communicate this.
For prior discussion, see #2583
When using `#[clap(flatten)]` inside of a `Subcommand`, we would do a
`from` instead of an `update`.
The challenge is knowing when we are
going into a flattened subcommand vs changing the variant. To resolve
this, I added a `Subcommand:has_subcommand(name)` trait method that we
generate, so we can ask.
Before, partial command lines would panic at runtime. Now it'll be a
compile error
For example:
```
pub enum Opt {
Daemon(DaemonCommand),
}
pub enum DaemonCommand {
Start,
Stop,
}
```
Gives:
```
error[E0277]: the trait bound `DaemonCommand: clap::Args` is not satisfied
--> clap_derive/tests/subcommands.rs:297:16
|
297 | Daemon(DaemonCommand),
| ^^^^^^^^^^^^^ the trait `clap::Args` is not implemented for `DaemonCommand`
|
= note: required by `augment_args`
```
To nest this, you currently need `enum -> struct -> enum`. A later
change will make it so you can use the `subcommand` attribute within
enums to cover this case.
This is a part of #2005
While having convinience derives can be helpful, deriving traits that
are not used in similar situations (`Clap` and `ArgEnum`) can make
things harder
- From a user, derives are opaque and create uncertainty on how to use
the API if not kept crystal clear (deriving a name gives you the trait
by that name)
- This makes documentation harder to write and read
- You can use types in unintended places, which is made worse for crate
APIs because changing this breaks compatibility.
Fixes#2584
Some more fixes in addition to 594c535ba2
* Some I noticed manually.
* Some were found by Topy (https://github.com/intgr/topy), either new
rules from Typo or new code in clap.
* `etc.` and `e.g.` rules were disabled during the last run.
