Fixes “Internal error. Invalid state while parsing command-line arguments.” that is encountered when an unparsed value is optional.
Root causes:
- `ParsedArgumentsContainer.decodeNil` returns false for optional values because it only does a `!contains(key)` check. This should instead return nil if the value of the element is nil.
- The decoder did not know about unparsed input origins that and would result in unexpected behavior when decoding nil default values.
- The `value` of `Mirror.Child` is defined as `Any` but this is confusing because the value could be `Optional<Any>` which is not equal to `nil` even when the `Optional` case is `.none`.
Co-authored-by: Mike <mike.wermuth@icloud.com>
* Allow variable properties in parsable types
This captures the default value for non-parsable properties
when building the ArgumentSet, which in turn get set as initial
values before decoding.
Matt Zanchelli
Mike WermuthandMike
Nate Cook
Guillaume Lessard
Šimon Javora