An `fn` type can be more annoying to produce in some generic
cases, and we haven't really needed it yet.
Signed-off-by: Wolfgang Bumiller <wry.git@bumiller.com>
Drop #!feature(specialization) in favor of having a `cli`
property for types to decide whether they are CLI
compatible.
The unconstrained_type! macro now has both ParseCli and
ParseCliFromStr in view, and requires one of the two to be
implemented for a type. This means that if a type implements
FromStr, it should "just work".
For types created without the help of the #[api] macro,
there's a shortcut to exclude a type from the CLI via
the no_cli_type!{typename} macro.
Signed-off-by: Wolfgang Bumiller <w.bumiller@proxmox.com>
