Private parameters are reported as unused

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• Make sure you are able to repro it on the latest released version
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Steps to reproduce

Run the analyzer against this script.

Param (
    [String] $private:var1
)

function Test-Second
{
    # $var1 is not accessible because it was private to the script.
    Write-Information -InformationAction "continue" "From script: $var1"

    # $var2 is not private to the calling function so we can access it.
    Write-Information -InformationAction "continue" "From caller: $var2"
}

function Test-NotGlobal
{
    Param (
        [String] $var2
    )
    $a = $var1 + " " + $var2
    Write-Information -InformationAction "continue" "Concatenation: $a"
    Test-Second
}

Test-NotGlobal $var1

Expected behavior

Expect no errors because $private:var1 and the use in the last line of $var1 are the same variable and $var1 is private to the script, as required.

Actual behavior

PS C:\Users\pauldsmith> Invoke-ScriptAnalyzer c:\temp\gvar.ps1

RuleName                            Severity     ScriptName Line  Message
--------                            --------     ---------- ----  -------
PSReviewUnusedParameter             Warning      gvar.ps1   2     The parameter 'private:var1' has been declared but not
                                                                  used.


PS C:\Users\pauldsmith>

If an unexpected error was thrown then please report the full error details using e.g. $error[0] | Select-Object *

Environment data

> $PSVersionTable

Name                           Value
----                           -----
PSVersion                      5.1.22621.963
PSEdition                      Desktop
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0...}
BuildVersion                   10.0.22621.963
CLRVersion                     4.0.30319.42000
WSManStackVersion              3.0
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1

> (Get-Module -ListAvailable PSScriptAnalyzer).Version | ForEach-Object { $_.ToString() }

1.21.0

Start by running Invoke-ScriptAnalyzer on the PowerShell reproduction and inspect the PSReviewUnusedParameter rule's implementation and coverage. Confirm that the private parameter and its final use are recognized as the same variable; done means the reproduction produces no unused-parameter warning.