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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Incidentally [psobject]-wrapped reference-type instances aren't recognized as their true type (base object) by cmdlet parameters","articleBody":"Note: \r\n\r\n* The problem was first discovered by @AlexKichkailo in #14384\r\n\r\n* It looks like another manifestation of #5579. That is, the usually invisible `[psobject]` wrapper that _cmdlets_ wrap around their output objects causes _cmdlet_ parameters not to recognize such wrapped instances as their underlying type (base object).\r\n\r\nNote that parameters declared in _PowerShell code_ (scripts, functions) are _not_ affected.\r\n\r\n## Steps to reproduce\r\n\r\n```powershell\r\n# Create a cmdlet that has a [System.Collections.ArrayList] parameter.\r\nAdd-Type @'\r\nusing System;\r\nusing System.Collections;\r\nusing System.Management.Automation;\r\n\r\n[Cmdlet(VerbsCommon.Get, \"HashCode\")]\r\npublic class AddCollectionItemCmdlet : Cmdlet\r\n{\r\n    [Parameter]\r\n    public ArrayList Collection { get; set; }\r\n\r\n    protected override void BeginProcessing()\r\n    {\r\n        WriteObject(Collection.GetHashCode());\r\n    }\r\n}\r\n'@ -PassThru | % Assembly | Import-Module\r\n\r\n# Use New-Object to create an array list.\r\n# Note: Unlike when you use the static ::new() method, you get an instance\r\n#       that is *wrapped in [psobject]*.\r\n$al = New-Object System.Collections.ArrayList\r\n\r\n$origHashCode = $al.GetHashCode()\r\n\r\n# OK: Bypassing the [psobject] wrapper.\r\nGet-HashCode -Collection $al.psobject.BaseObject | Should -Be $origHashCode\r\n\r\n# !! BROKEN: Seemingly the array list is *cloned* if the input object\r\n# !!         is [psobject]-wrapped.\r\nGet-HashCode -Collection $al | Should -Be $origHashCode\r\n```\r\n\r\n## Expected behavior\r\n\r\nBoth tests should pass.\r\n\r\n## Actual behavior\r\n\r\nThe second test fails, because the `[psobject]`-wrapped  input` [System.Collections.ArrayList]` instance was seemingly _cloned_ behind the scenes, so the hash codes differ.\r\n\r\n## Environment data\r\n\r\n```none\r\nPowerShell Core 7.2.0-preview.1\r\n```\r\n","author":{"url":"https://github.com/mklement0","@type":"Person","name":"mklement0"},"datePublished":"2020-12-11T13:19:55.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":4},"url":"https://github.com/14394/PowerShell/issues/14394"}