Single word is not completed in PowerShell

[totkeks]

When I use the Powershell completion in oh-my-posh (JanDeDobbeleer/oh-my-posh#3050), it fails to complete when I want to complete the first word, e.g. con<tab> or com<tab> - should result in config or completion respectively. Instead neither happens.

After a little digging I found that OMP uses this project and that the PowerShell completion might have a bug.

$Values = $Out | ForEach-Object {
		#Split the output in name and description
		$Name, $Description = $_.Split("`t", 2)
		__oh-my-posh_debug "Name: $Name Description: $Description"

		# Look for the longest completion so that we can format things nicely
		if ($Longest -lt $Name.Length) {
			$Longest = $Name.Length
		}

		# Set the description to a one space string if there is none set.
		# This is needed because the CompletionResult does not accept an empty string as argument
		if (-Not $Description) {
			$Description = " "
		}
		@{Name = "$Name"; Description = "$Description" }
	}

When there is only one completion result, which is oddly the case for oh-my-posh __complete con but not for oh-my-posh __complete config ex, then the above code makes $Values a hashtable and not an array, which results in a hidden error down the line, because a hashtable has no Length property.

if (($Directive -band $ShellCompDirectiveNoFileComp) -ne 0 ) {
		__oh-my-posh_debug "ShellCompDirectiveNoFileComp is called";

		if ($Values.Length -eq 0) {
			# Just print an empty string here so the
			# shell does not start to complete paths.
			# We cannot use CompletionResult here because
			# it does not accept an empty string as argument.
			""
			return
		}
	}

My simple workaround has been forcing $Values to become an array by doing this [Array]$Values in the first code fragment.

[marckhouzam]

Thanks for the report @totkeks.
At the moment I have tested using powershell on a Mac and I cannot reproduce the problem using helm comp<TAB>.

My powershell version is PowerShell 7.2.4.
Are you seeing the problem on a Windows machine?
What version of Powershell do you use?

[totkeks]

I'm using 7.2.7 on Windows. It might be that helm produces more than one suggestion with the __complete command that is internally called.

For example oh-my-posh delivers this output for just conf

> oh-my-posh __complete conf
config  Interact with the config
:4
Completion ended with directive: ShellCompDirectiveNoFileComp

And this for config ex

> oh-my-posh __complete config ex
export  Export your config
export
:4
Completion ended with directive: ShellCompDirectiveNoFileComp

It might be that your helm command returns more than one result for the completion you requested in your test. The issue only appears if there is only a single suggestion returned by the __complete call.

[marckhouzam]

I installed oh-my-posh on my Mac and upgraded to powershell 7.2.7 and I still can't reproduce.

For example oh-my-posh delivers this output for just conf

> oh-my-posh __complete conf
config  Interact with the config
:4
Completion ended with directive: ShellCompDirectiveNoFileComp

This should be fine. I see the same thing.

And this for config ex

> oh-my-posh __complete config ex
export  Export your config
export
:4
Completion ended with directive: ShellCompDirectiveNoFileComp

This is also fine, although it is actually bizarre that export appears twice. I looked at the code and I believe it is because export is a sub-command but also listed as a validArg here: https://github.com/JanDeDobbeleer/oh-my-posh/blob/0ce34eef12d5b4f4fc90ad32dfeec2209e093e4a/src/cli/config.go#L18-L22

But that is not causing a problem anyway.

Maybe the hash vs array only happens on windows. I'll see if I can test on Windows.

Just to be clear, this is how I test things:

$ pwsh
PowerShell 7.2.7
Copyright (c) Microsoft Corporation.

https://aka.ms/powershell
Type 'help' to get help.

PS /tmp> ./oh-my-posh completion powershell | Out-String | Invoke-Expression
PS /tmp> ./oh-my-posh conf<tab>
PS /tmp> ./oh-my-posh config

[totkeks]

Thanks for the update. Yes, your code is correct, that's how I do it, except the last line, which it doesn't complete to.

Another option to test this, also on your Mac, would be to see if they use a different way to handle ForEach-Object:

> (@(1,2) |foreach-object { @{Name = $_ } }).GetType().Name
Object[]

> (@(1) | foreach-object { @{Name = $_ } }).GetType().Name
Hashtable

The first line should return Object[] and the second line should return Hashtable.

[marckhouzam]

> (@(1,2) |foreach-object { @{Name = $_ } }).GetType().Name
Object[]

> (@(1) | foreach-object { @{Name = $_ } }).GetType().Name
Hashtable

Same result for me.
I wonder if it could be something to do with descriptions.
Could you turn off descriptions and see if it changes anything? To turn off descriptions instead of __complete use __completeNoDesc. So you can do this:

oh-my-posh completion powershell | sed s,__complete,__completeNoDesc,g | Out-String | Invoke-Expression
oh-my-posh com<tab>

[totkeks]

It didn't change anything. But I figured out why it doesn't work for me but works for you. In my PowerShell profile I have Set-StrictMode -Version Latest.
https://learn.microsoft.com/en-us/powershell/module/microsoft.powershell.core/set-strictmode?view=powershell-7.2

When Set-StrictMode is off, PowerShell has the following behaviors:
[...]
* References to non-existent properties return $Null

With strict mode on, the opposite happens and since Hashtable has no Length property, an exception is thrown.

According to this old, archived post, they added a feature in PowerShell V3, that lets Length return the same value as Count.
https://web.archive.org/web/20150612170424/http://blogs.msdn.com/b/powershell/archive/2012/06/14/new-v3-language-features.aspx
Which is why the comparison $Values.Length -eq 0 works for you.

So, I guess I'm the only person that has strict mode enabled. 😅

Would you mind changing the template code to this, for the sake of correctness?

[Array]$Values = $Out | ForEach-Object {

[marckhouzam]

Thanks for figuring this out!
Do you want to post a PR?

[totkeks]

Yes, I want to do that. I haven't done this before but would like to as a learning experience. I will get to it in the next few days.