`Set-StrictMode 2`: False positive for references to the `Count` property

Prerequisites

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Steps to reproduce

Set-StrictMode -Version Latest
$TempFile = New-TemporaryFile
$TempPath = Join-Path $Env:Temp ('Folder_' + [Guid]::NewGuid())
$TempFolder = New-Item -ItemType Directory -Path $TempPath
Copy-Item -Path $TempFile -Destination $TempFolder
$TempFolder |Should -Exist
(Get-ChildItem $TempFolder).Count |Should -Be 1

Expected behavior

No Error

Actual behavior

PropertyNotFoundException: The property ‘Count’ cannot be found on this object. Verify that the property exists.

Error details

With Set-StrictMode -Off the (Get-ChildItem $TempFolder).Count return 1 which shows that the property does exist

Environment data

Name                           Value
----                           -----
PSVersion                      7.2.0
PSEdition                      Core
GitCommitId                    7.2.0
OS                             Microsoft Windows 10.0.22000
Platform                       Win32NT
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0…}
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1
WSManStackVersion              3.0

[vexx32]

That makes sense to me. If strict mode is intended to by design restrict usage of otherwise ubiquitous properties provided by the engine, that should be well documented. Given that it’s not (as far as I’m aware?), I would be inclined to assume it’s more of an accident of implementation and we should see if it’s feasible to rectify the issue.

[mklement0]

Note that this problematic behavior was first reported in

• https://github.com/PowerShell/PowerShell/issues/2798

#15526 also discusses the inconsistency, but argues for the opposite resolution; to borrow from my comment there:

Engine-supplied members such as .Count, .Length, scalar [...], .psobject, ForEach(), … now have an official name: intrinsic members.

It makes much more sense to make them consistently available, irrespective of strict mode.

This is already true for most of them, but inexplicably not for .Count and .Length ([pscustomobject] being the only exception), despite their tremendous usefulness in unified handling of scalars and collections.

Simplest repro:

# .Count fails on all types without their own .Count property  *except* [pscustomobject]`
# Applies analogously to .Length
& { Set-StrictMode -Version 2; [pscustomobject] @{ foo=1 }.Count; 'foo'.Count; $null.Count }

@iRon7, your [string[]] $StringArray parameter example can be reduced to $null.Count, because unbound reference-type parameters (without default values) are $null.