zsh completions for commands that have multiple Vec arguments require
special care.
We can have two Vec args separated with a value terminator.
We can also have two Vec args with no value terminators specified
where the final arg uses 'raw' and thus requires '--' to be used.
The 2nd of these scenarios requires special handling to avoid
emitting a duplicate '*:arguments' completion entry.
Currently, the zsh completions generate an error in this scenario:
$ my-app <TAB>
_arguments:...: doubled rest argument definition:
*::second -- second set of of multi-length arguments:
We already use the '-S' option when calling _arguments.
This option makes it so that completion stops after '--' is encountered.
This means that the handling for trailing 'raw' arguments does not need
to specified.
Special-case multi-valued arguments so that we can skip emitting
the final multi-valued argument if a previous multi-valued argument
has already been emitted.
Closes#3022
Signed-off-by: David Aguilar <davvid@gmail.com>
