Write-Output $null -NoEnumerate produces different Collection<PSObject> in 5.1 vs 6.0

I'm not sure which behavior is better, but I expected 5.1 and 6.0 to behave the same in this respect. If this change is deliberate I would like to understand why.

Steps to reproduce

$r = [System.Collections.ObjectModel.Collection[psobject]]{Write-Output $null -NoEnumerate}.Invoke()
$r.item(0).GetType()

Behavior in PowerShell 5.1

You cannot call a method on a null-valued expression.
At C:\Users\un1\Desktop\test.ps1:2 char:1
+ $r[0].GetType()
+ ~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidOperation: (:) [], RuntimeException
    + FullyQualifiedErrorId : InvokeMethodOnNull

>$PSVersionTable

Name                           Value                                                                    
----                           -----                                                                    
PSVersion                      5.1.14409.1012                                                           
PSEdition                      Desktop                                                                  
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0...}                                                  
BuildVersion                   10.0.14409.1012                                                          
CLRVersion                     4.0.30319.42000                                                          
WSManStackVersion              3.0                                                                      
PSRemotingProtocolVersion      2.3                                                                      
SerializationVersion           1.1.0.1

Behavior in PowerShell 6.0

IsPublic IsSerial Name                                     BaseType
-------- -------- ----                                     --------
True     True     PSObject[]                               System.Array

> $PSVersionTable

Name                           Value                                            
----                           -----                                            
PSVersion                      6.0.2                                            
PSEdition                      Core                                             
GitCommitId                    v6.0.2                                           
OS                             Microsoft Windows 6.3.9600                       
Platform                       Win32NT                                          
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0...}                          
PSRemotingProtocolVersion      2.3                                              
SerializationVersion           1.1.0.1                                          
WSManStackVersion              3.0

Indeed, Write-Output is broken - see #5955 and #5122, and it all seems to be the result of the ill-fated #2038 PR that arose out of issue #2035.

Oi. That's a messy broken business, indeed.

It looks like this change to Write-Output is the culprit. Copying the command from the revision prior and renaming to Write-Output2 seems to result in behavior consistent with PowerShell 5.1:

Add-Type '
    using System.Management.Automation;

    [Cmdlet(VerbsCommunications.Write, "Output2")]
    public class WriteOutput2Command : PSCmdlet
    {
        private PSObject[] _inputObjects = null;

        [Parameter(Position = 0, Mandatory = true, ValueFromPipeline = true, ValueFromRemainingArguments = true)]
        [AllowNull]
        [AllowEmptyCollection]
        public PSObject[] InputObject
        {
            get { return _inputObjects; }
            set { _inputObjects = value; }
        }

        [Parameter()]
        public SwitchParameter NoEnumerate
        {
            get;
            set;
        }

        protected override void ProcessRecord()
        {
            if (null == _inputObjects)
            {
                WriteObject(_inputObjects);
                return;
            }

            bool enumerate = true;
            if (NoEnumerate.IsPresent)
            {
                enumerate = false;
            }
            foreach (PSObject inputObject in _inputObjects)
            {
                WriteObject(inputObject, enumerate);
            }
        }//processrecord
    }' -PassThru | % Assembly | Import-Module

$r = [System.Collections.ObjectModel.Collection[psobject]]{Write-Output2 $Null -NoEnumerate}.Invoke()
$r.Item(0).GetType()

outputs

You cannot call a method on a null-valued expression.
At C:\users\un1\Desktop\test2.ps1:46 char:1
+ $r.Item(0).GetType()
+ ~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidOperation: (:) [], RuntimeException
    + FullyQualifiedErrorId : InvokeMethodOnNull

Fix accidental wrapping of scalar Write-Output input

This issue has not had any activity in 6 months, if this is a bug please try to reproduce on the latest version of PowerShell and reopen a new issue and reference this issue if this is still a blocker for you.

This issue has been marked as "No Activity" as there has been no activity for 6 months. It has been closed for housekeeping purposes.

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Write-Output $null -NoEnumerate produces different Collection<PSObject> in 5.1 vs 6.0 #6451

Steps to reproduce

Behavior in PowerShell 5.1

Behavior in PowerShell 6.0

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Write-Output $null -NoEnumerate produces different Collection<PSObject> in 5.1 vs 6.0 #6451

Description

Steps to reproduce

Behavior in PowerShell 5.1

Behavior in PowerShell 6.0

Activity

mklement0 commented on Mar 21, 2018

alx9r commented on Mar 21, 2018

alx9r commented on Mar 21, 2018

microsoft-github-policy-service commented on Nov 16, 2023

microsoft-github-policy-service commented on Nov 16, 2023

microsoft-github-policy-service commented on Nov 16, 2023

microsoft-github-policy-service commented on Nov 23, 2023

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