While working on adding descriptions to the custom completions for helm, I ran into two bugs with zsh and ShellCompDirectiveNoSpace.

Say I have the following ValidArgsFunction for command nospace:

ValidArgsFunction: func(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
		if len(args) == 0 {
			return []string{"when\tThe time", "who\tThe person"}, cobra.ShellCompDirectiveNoSpace
		}
		return []string{"why\tThe reason"}, cobra.ShellCompDirectiveNoSpace
	},

Bug 1: NoSpace is not respected
If I run in zsh:

$ ./testprog nospace whe<TAB>

a space is added after ./testprog nospace when even though the ShellCompDirectiveNoSpace was given.

This is because the script only handles ShellCompDirectiveNoSpace if a single completion is returned:

But my ValidArgsFunction does not filter the completion but instead returns all of them, leaving zsh to filter them. In this case:

$ ./testprog __complete nospace whe<ENTER>
when	The time
who	The person
:2
Completion ended with directive: ShellCompDirectiveNoSpace

Notice that with the result above the completion script would receive two completions even though the who completion is not technically valid. But this is allowed.

Bug 2: Descriptions are not handled with ShellCompDirectiveNoSpace
The zsh script was using compadd directly to handle ShellCompDirectiveNoSpace:

The problem is that compadd does not handle descriptions and just prints them as part of the completion. So, in my case:

$ ./testprog nospace when w<TAB>

will complete to:

./testprog nospace when why:The\ reason

I will post a PR to handle this better.