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

# The *presence* of the switch selects UseWindowsPowerShellParameterSet.
# Irrespective of the switch *value*, CreateRunspacesForUseWindowsPowerShellParameterSet() is called.
# This subverts reasonable user expectation. UseWindowsPowerShell was NOT requested, yet the command
# ignores that request.
New-PSSession -UseWindowsPowerShell:$false

# Likewise, this results in [datetime] output, despite it not being requested.
$params = @{ Since = $false }
Get-Uptime @params

Context:

This is a continuation of the following issues:

• Get-Uptime -Since ignores an explicit $false value #25015
• Treat -Switch:$false the same as omitting a switch when selecting a parameter set #25027

Summary:

• The first issue discusses how Get-Uptime -Since:$false is not respected. That is, despite the explicit $false value, Get-Uptime behaves as if -Since or -Since:$true was specified.
  • This behavior was deemed erroneous and the issue was labelled Up-for-grabs.
• The second issue is a proposal by @mklement0 for a systematic change that would implicitly fix the Get-Uptime issue and other commands that exhibit the same problem.
  • This proposal was rejected due to backwards compatibility concerns.
• I encountered at least 10 commands shipped with PowerShell that exhibit the same problem when looking into the issue further. See here.
• Per @iSazonov in #25015:

Up-for-Grabs - we should fix all cmdlets in the repo if they implement a switch in wrong way.

List of commands to fix:

• Get-Uptime -Since Get-Uptime -Since ignores an explicit $false value #25015
• New-Guid -Empty New-Guid -Empty ignores an explicit $false value #25276
• Get-Random -Shuffle -Shuffle:$false not respected in Get-Random #26456
• Get-SecureRandom -Shuffle Respect -Shuffle:$false in Get-SecureRandom #26460
• Get-TimeZone -ListAvailable -ListAvailable:$false not respected in Get-TimeZone #26462
• New-PSSession -UseWindowsPowerShell -UseWindowsPowerShell:$false not respected in New-PSSession #26464
• Split-Path -Qualifier/-NoQualifier/-Leaf/-IsAbsolute (not -Extension/-LeafBase) -Qualifier/-NoQualifier/-Leaf/-IsAbsolute:$false not respected in Split-Path #26470
• Test-Connection -Repeat/-MtuSize/-Traceroute -Repeat/-MtuSize/-Traceroute:$false not respected in Test-Connection #26475
• Where-Object (all non-common switch parameters) -[Operator]:$false not respected in Where-Object #26480
• ConvertTo-Csv -UseCulture:$false ConvertTo-Csv/Export-Csv -UseCulture:$false uses the wrong delimiter in ouput #26513
• Export-Csv -UseCulture:$false ConvertTo-Csv/Export-Csv -UseCulture:$false uses the wrong delimiter in ouput #26513
• ConvertFrom-Csv -UseCulture:$false
• Import-Csv -UseCulture:$false
• Get-Culture -ListAvailable:$false
• Get-Location -Stack:$false

Request

Fix each command listed above individually, so that explicitly passing a $false value to the specified switch parameter is respected.

Expected behavior

-Switch:$false results in the same behavior as not passing -Switch.

Actual behavior

For the commands listed above, -Switch:$false results in the same behavior as -Switch or -Switch:$true.

Environment data

Name                           Value
----                           -----
PSVersion                      7.6.0-preview.3
PSEdition                      Core
GitCommitId                    7.6.0-preview.3
OS                             Microsoft Windows 10.0.19045
Platform                       Win32NT
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0, 5.0, 5.1…}
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1
WSManStackVersion              3.0