false positive 'PSUseDeclaredVarsMoreThanAssignments'

[mwallner]

I get the message 'The variable 'param' is assigned but never used.'
My script looks like this:

$param = $MyInvocation.BoundParameters

a couple of lines further down in the same script:

. "$PSScriptRoot\wrap.script.ps1 @param"

[TheRealHotFix]

Same here:
The variable 'NewFileArray' is assigned but never used.
Here is the code:
`# Create an array to hold the new file attributes (skipping the "Entry #" attribute since that is not stored in the AD attribute field).
$NewFileArray = @()
$NewFileEntry.PSObject.Properties | Where-Object {$.Name -notlike "Entry"} | ForEach-Object {
# Join the name and value of each attribute, using the colon character as a delimiter.
$NewFileArray += $.Name + ":" + $_.Value
}

Create an ADSI connection to the Service Account defined in the Main Window, and set the custom attribute (extensionAttribute) to the Entry #.

$UpdateAccount = [ADSI]$($SvcAccount.Properties.adspath).ToString()
$ADAttribute = "extensionAttribute" + $NewFileEntry.Entry

Check to see if there were any entries in the array after excluding the Entry #.

If ($NewFileArray) {
# There were so join them in a contiguous string using the comma character as a delimiter, and then store that string in the custom attribute.
$UpdateAccount.$ADAttribute = $NewFileArray -join ","
} Else {
# There weren't so blank the attribute because someone must have cleared them in the Edit Window.
$UpdateAccount.$ADAttribute.Clear()
}`

[mwallner]

bump

It'd be great to get this fixed - getting a lot of false positives in a couple of projects.
(yes - most likely due to a certain coding style - but it's still an issue ;-))

[daviwil]

Hey @kapilmb can you take a look and see how much effort it might take to get this resolved for an upcoming release?

[kapilmb]

Fixing this rule requires some non-trivial amount of work. Right now the rule implementation is pretty ad-hoc. We would need to completely rewrite the rule to use analysis by single static assignment (SSA) form. One positive thing is that we do have a preliminary implementation of SSA, but it needs some modification. Will try to see to what I can do for the upcoming release but there is a good chance I won't make it by then.

[kapilmb]

@daviwil When are we planning the next feature release? I might be able to make dash for this if there is some margin.

[davebrannan]

I also see this when I declare a variable in a module and export it using Export-ModuleMember.

[DexterPOSH]

bump
I am still seeing the false positives. As explained here #699

[gwojan]

I just noticed this bug... It appears any time a variable is assigned inside {} resulting in a false positive being identified by PSScriptAnalyzer.

$bubba = 'Hi there'
1..2 | % { $bubba = 'Some contrived value' }
$bubba

OR

$bubba = ''
{ $bubba = 'assign something here' }
$bubba

[DarqueWarrior]

It is also triggered when you assign an environment variable like this.
$env:TEAM_PAT = $Pat

[PowerDBAKlaas]

I have this example where a property of the variable is used:

[ThubLives]

I'm seeing this when a variable is assigned a value inside specific script block types and no other reference is made within the same script block. I'm using VS Code 1.16.0 and ms-vscode.powershell 1.4.2.

So far I've only seen two types of script blocks exhibiting the problem: ForEach-Object and Where-Object. Someone above mentioned arbitrary script blocks like

$ScriptBlock = {
  $ScriptBlock = 'No script here'
}
Invoke-Command $ScriptBlock

but I'm pretty sure it's working as designed, because it's got its own scope, so $ScriptBlock should not redefine itself.

These ones are unaffected, though if they are wrapped in another, problematic script block type, the problem will still occur: if, else, elseif, do, while, try, catch, and finally.

For example, the second instance of $IsEven is marked as PSUseDeclaredVarsMoreThanAssignments, but moving it outside the ForEach-Object block clears the warning:

$IsEven = $false
@(2, 3, 5, 7, 11, 13, 17) | ForEach-Object {
  if (($_ % 2) -eq 0) {
    $IsEven = $true
  }
}

if ($IsEven) {
  Write-Host "At least one of the numbers is even."
}

[jdkang]

I'm seeing this specifically with assigning values to collections inside a a foreach-object and using the collection later -- either as a reference or iterating over it.

EXAMPLE:

    # Export Functions and DSC Resources in src\Public
    [string[]]$funcsToExport = @()
    [string[]]$dscResToExport = @()
    Get-ChildItem -Path "$moduleDestPath\src\Public" -Filter *.ps1 |
        & $BuildRoot\build\Find-PsFuncOrDscRes.ps1 |
        Foreach-Object {
            if($_.Functions.Count -gt 0) {
                $funcsToExport += ($_.Functions.Name)
            }
            if($_.DscResources -gt 0) {
                $dscResToExport += ($_.DscResources.Name)
            }
        }
    if($funcsToExport.Count -gt 0) {
        $moduleManifestSplat['FunctionsToExport'] = $funcsToExport
    }
    if($dscResToExport.Count -gt 0) {
        $moduleManifestSplat['DscResourcesToExport'] = $dscResToExport
    }