TabExpansion2 should have help

[ThomasNieto]

Prerequisites

• Write a descriptive title.
• Make sure you are able to repro it on the latest released version
• Search the existing issues.
• Refer to the FAQ.
• Refer to Differences between Windows PowerShell 5.1 and PowerShell.

Steps to reproduce

If you run Get-Help TabExpansion2 no help is returned. I am creating this issue here instead of PowerShell-Docs since the command doesn't belong to any module and is defined in code in the following reference.

cc: @sdwheeler

PowerShell/src/System.Management.Automation/engine/InitialSessionState.cs

Lines 4028 to 4081 in 9fe339b

	private static readonly string s_tabExpansionFunctionText = @"
	<# Options include:
	RelativeFilePaths - [bool]
	Always resolve file paths using Resolve-Path -Relative.
	The default is to use some heuristics to guess if relative or absolute is better.
	To customize your own custom options, pass a hashtable to CompleteInput, e.g.
	return [System.Management.Automation.CommandCompletion]::CompleteInput($inputScript, $cursorColumn,
	@{ RelativeFilePaths=$false }
	#>
	[CmdletBinding(DefaultParameterSetName = 'ScriptInputSet')]
	[OutputType([System.Management.Automation.CommandCompletion])]
	Param(
	[Parameter(ParameterSetName = 'ScriptInputSet', Mandatory = $true, Position = 0)]
	[AllowEmptyString()]
	[string] $inputScript,
	[Parameter(ParameterSetName = 'ScriptInputSet', Position = 1)]
	[int] $cursorColumn = $inputScript.Length,
	[Parameter(ParameterSetName = 'AstInputSet', Mandatory = $true, Position = 0)]
	[System.Management.Automation.Language.Ast] $ast,
	[Parameter(ParameterSetName = 'AstInputSet', Mandatory = $true, Position = 1)]
	[System.Management.Automation.Language.Token[]] $tokens,
	[Parameter(ParameterSetName = 'AstInputSet', Mandatory = $true, Position = 2)]
	[System.Management.Automation.Language.IScriptPosition] $positionOfCursor,
	[Parameter(ParameterSetName = 'ScriptInputSet', Position = 2)]
	[Parameter(ParameterSetName = 'AstInputSet', Position = 3)]
	[Hashtable] $options = $null
	)
	End
	{
	if ($psCmdlet.ParameterSetName -eq 'ScriptInputSet')
	{
	return [System.Management.Automation.CommandCompletion]::CompleteInput(
	<#inputScript#> $inputScript,
	<#cursorColumn#> $cursorColumn,
	<#options#> $options)
	}
	else
	{
	return [System.Management.Automation.CommandCompletion]::CompleteInput(
	<#ast#> $ast,
	<#tokens#> $tokens,
	<#positionOfCursor#> $positionOfCursor,
	<#options#> $options)
	}
	}
	";

Expected behavior

`Get-Help TabExpansion2` has help

Actual behavior

No help

Error details

No response

Environment data

7.4.1

Visuals

No response

[sdwheeler]

It is mentioned here: https://learn.microsoft.com/en-us/powershell/module/microsoft.powershell.core/about/about_built-in_functions?view=powershell-7.4#tabexpansion2

But it doesn't tell you how to use it. I don't know if the PowerShell team ever intended it to be used externally. But I will find out. I still like the idea of a blog post.

about Built-in Functions - PowerShell

Describes the built-in functions in PowerShell.

[ThomasNieto]

@sdwheeler This function is similar to Out-Default where it is not intended to be used by the end user but does have help to explain what it is used for in the console.

[SteveL-MSFT]

TabExpansion2 isn't intended to be used by end-users, but it is used by developers to test tab completion. As such, we should probably have some docs on it, but also probably not promote usage of it.

[ThomasNieto]

@SteveL-MSFT in that case there should be help for it saying its not intended for end users like Out-Default does. There is already docs on the PowerShell help site describing what it is but there is nothing in the console if someone stumbles across the function in that native help system.