PSUseDeclaredVarsMoreThanAssignment not correctly handling array adds

Given the following code

$msg = @()
@("a", "b") | ForEach-Object { $msg += $_ }
Write-Information $msg -InformationAction Continue

I get the following warning:

The variable 'msg' is assigned but never used. (line 2)

I realize that this generates a new array each time, but it is both being assigned to and read, so this appears to be a false positive.

Another similar scenario:

$params = (@{"a" = 1; "b" = 2}).GetEnumerator() |
    ForEach-Object { $m = @{} } { $m[$_.Name] = $_.Value } { $m } # foreach begin{} process{} end{}
$params

The variable 'm' is assigned but never used. (line 2)

Fix static analysis warnings

bump

Is this fixed already? I still see these false positives.

PS>gmo PSScriptAnalyzer

ModuleType Version    Name                                ExportedCommands
---------- -------    ----                                ----------------
Script     1.15.0     PSScriptAnalyzer                    {Get-ScriptAnalyzerRule, Invoke-Formatter, Invoke-ScriptAn...


PS>Invoke-ScriptAnalyzer  -ScriptDefinition {  $jobs=@()
>>                     $ipList | ForEach-Object {
>>                         $running = @(Get-Job | Where-Object { $_.State -eq 'Running' })
>>                         if ($running.Count -ge 10)
>>                         {
>>                             $running | Wait-Job -Any | Out-Null
>>                         }
>>                         Write-Verbose "Discovering ip $_"
>>                         $jobs += Start-Job -ScriptBlock $cmd -ArgumentList $_, $credential, $deepDiscover
>>                     }
>>                     Wait-Job -Job $jobs | Out-Null
>>                     Receive-Job -Job $jobs
>>                 }.ToString()

RuleName                            Severity     ScriptName Line  Message
--------                            --------     ---------- ----  -------
PSUseDeclaredVarsMoreThanAssignment Warning                 9     The variable 'jobs' is assigned but never used.
s

It's not the array, it's the ForEach loop

It also happens if you define a variable in the begin block of the ForEach, like this:

$Doubles = 1..100 | ForEach { $collect = @() } { $Collect += $_ * 2 } { $Collect }

Or when you use a hashtable like:

$Requirement = Get-Item .
[hashtable]$hash = $Requirement.PSObject.Properties.Where{$_.Value} | ForEach-Object { $ht = @{} } { $ht.Add($_.Name, $_.value) } { $ht }
$hash

Joel Bennett (@Jaykul)

Joel Bennett (@Jaykul) Actually, it is a problem of both the += operator being treated as assignment (not usage) , I will therefore extract your examples (that I think are valid) because I found a solution to the originally raised issue that is due to +=

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PSUseDeclaredVarsMoreThanAssignment not correctly handling array adds #699

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PSUseDeclaredVarsMoreThanAssignment not correctly handling array adds #699

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DexterPOSH commented on Jul 6, 2017

Jaykul commented on Dec 22, 2017

bergmeister commented on Mar 14, 2018

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