Question about 'PSUseDeclaredVarsMoreThanAssignment' rule

[LaurentDardenne]

This code triggers a violation :

$isduplicate=$false
Get-ChildItem c:\|
  Foreach-Object {
   $isDuplicate=$true
 }

This one too :

$isduplicate=$false
Get-ChildItem c:\|
  Foreach-Object {
   $isDuplicate=$true
 }
$isDuplicate
#true

But not this one :

$isduplicate=$false
Get-ChildItem c:\|
  Foreach-Object {
 }
$isDuplicate

It is the first violation correct ?

[kapilmb]

The first violation is not correct but it is a due to the limitation of the rule's implementation - It doesn't inspect downstream scopes for a variable's use. The second case is a bug

[kapilmb]

Moving this to backlog as the the current solution (in #655) to this problem is more of a patchwork and error prone. In order to solve this problem properly, we need to make use of techniques like SSA. PSSA currently has an implementation but that needs to be updated in order to use it in this context. Once we have that capability, we will fix this issue.

[it-praktyk]

Probably the same issue is visible for code included in Pester project e.g. for the file build.psake.ps1

PSScriptAnalyzer output

and code

[markwragg]

I found today that $Variable += $Something triggers a PSUseDeclaredVarsMoreThanAssignments warning. Is that known?

Changing it to $Variable = $Variable + $Something works around it, but should += be causing this to trrigger?