Completions can be called from Help and it's hard to make the distinction

[guillaume86]

Currently if I don't want to show completions in the help text, I have to ressort to this method to detect if that was the help that called my completions (and that only works because I use subcommands):

private static bool IsHelpCall(CompletionContext context)
{
    return context.ParseResult.CommandResult?.Command is RootCommand;
}

I'd like to have an API for this, maybe adding an enum "InvocationContext(Suggest|ShowHelp)" to the CompletionContext?

It's not crucial to the issue but here are a few reasons I want to show different results:

• completions can be slow to return
• there can be a lot of results, especially if WordToComplete is empty
• I just don't want to show them in the help text

[jonsequitur]

Have you looked at the HelpBuilder.CustomizeSymbol APIs? I think these can be used to replace the default completions behavior but I'm not certain of it. If they can't be used this way then we should fix that. I'll give it a try as well and report back.

[KalleOlaviNiemitalo]

I had some difficulty reproducing this issue because I did not know that the default help displays the completions only for Argument and not for Option.

command-line-api/src/System.CommandLine/Help/HelpBuilder.Default.cs

Lines 67 to 71 in 209b724

	var completions = (argument is { } a
	? a.GetCompletions()
	: Array.Empty<CompletionItem>())
	.Select(item => item.Label)
	.ToArray();