UseDeclaredVarsMoreThanAssignments

Severity Level: Warning

Default state: Always enabled

Description

This rule detects variables that are assigned a value but never used. A variable counts as "used" only when code references it in the same script block as its assignment. Variables that exist only as assignments add noise to the code and should be removed.

Example

Noncompliant

function Test
{
    $declaredVar = 'Declared just for fun'
    $declaredVar2 = 'Not used'
    Write-Output $declaredVar
}

Compliant

function Test
{
    $declaredVar = 'Declared just for fun'
    Write-Output $declaredVar
}

Special cases

The following examples trigger the PSUseDeclaredVarsMoreThanAssignments warning. This behavior is a limitation of the rule. There's no way to avoid these false positive warnings.

In this case, the warning is triggered because $bar isn't used within the scriptblock where it was defined.

$foo | ForEach-Object {
    if ($_ -eq $false) {
        $bar = $true
    }
}

if($bar){
    Write-Host 'Collection contained a false case.'
}

In the next example, the warning is triggered because $errResult isn't recognized as being used in the Write-Host command.

$errResult = $null
Write-Host 'Ugh:' -ErrorVariable errResult

Configure rule

This rule is always enabled and isn't configurable. Use one of the following methods to avoid using this rule:

• Create a custom rule configuration file to include only the rules you want or exclude the rules you don't want.
• Add the appropriate rule suppression attributes to your code to suppress the rule for specific code blocks. For more information, see the Suppressing rules section of Using PSScriptAnalyzer.