NullReferenceException on PSShouldProcess Rule.

[avezinaATastus]

Before submitting a bug report:

• Make sure you are able to repro it on the latest released version
• Perform a quick search for existing issues to check if this bug has already been reported

Steps to reproduce

I'm using PowerShellBuild and my module was made with Stucco.

I haven't changed the template. And the Analyze task was working fine yesterday.

I can't give steps to reproduce yet, working on it. Could I send someone my zipped module ? Not ready to make my code full public.

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

PSMessageDetails      : 
Exception             : System.NullReferenceException: Object reference not set to an instance of an object.
                           at Microsoft.Windows.PowerShell.ScriptAnalyzer.BuiltinRules.UseShouldProcessCorrectly.TryGetShouldProcessValueFromAst(FunctionInfo functionInfo, Boolean& hasShouldProcessSet)
                           at Microsoft.Windows.PowerShell.ScriptAnalyzer.BuiltinRules.UseShouldProcessCorrectly.SupportsShouldProcess(String cmdName)
                           at Microsoft.Windows.PowerShell.ScriptAnalyzer.BuiltinRules.UseShouldProcessCorrectly.CheckForSupportShouldProcess()
                           at Microsoft.Windows.PowerShell.ScriptAnalyzer.BuiltinRules.UseShouldProcessCorrectly.<AnalyzeScript>d__7.MoveNext()
                           at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
                           at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
                           at Microsoft.Windows.PowerShell.ScriptAnalyzer.ScriptAnalyzer.<>c__DisplayClass83_1.<AnalyzeSyntaxTree>b__2()
TargetObject          : C:\Users\avezina\gitrepos\etl.devops.serviceManagement\Output\ServiceManagement\0.6.2\Formatting\Deployment.format.ps1
CategoryInfo          : InvalidOperation: (C:\Users\avezin...ment.format.ps1:String) [Invoke-ScriptAnalyzer], NullReferenceException
FullyQualifiedErrorId : RULE_ERROR,Microsoft.Windows.PowerShell.ScriptAnalyzer.Commands.InvokeScriptAnalyzerCommand
ErrorDetails          : 
InvocationInfo        : System.Management.Automation.InvocationInfo
ScriptStackTrace      : at Test-PSBuildScriptAnalysis, C:\Users\avezina\Documents\WindowsPowerShell\Modules\PowerShellBuild\0.4.0\Public\Test-PSBuildScriptAnalysis.ps1: line 31
                        at <ScriptBlock>, C:\Users\avezina\Documents\WindowsPowerShell\Modules\PowerShellBuild\0.4.0\psakeFile.ps1: line 66
                        at Invoke-Task, C:\Users\avezina\Documents\WindowsPowerShell\Modules\psake\4.8.0\public\Invoke-Task.ps1: line 108
                        at <ScriptBlock>, C:\Users\avezina\Documents\WindowsPowerShell\Modules\psake\4.8.0\public\Invoke-psake.ps1: line 300
                        at ExecuteInBuildFileScope, C:\Users\avezina\Documents\WindowsPowerShell\Modules\psake\4.8.0\private\ExecuteInBuildFileScope.ps1: line 55
                        at Invoke-psake, C:\Users\avezina\Documents\WindowsPowerShell\Modules\psake\4.8.0\public\Invoke-psake.ps1: line 258
                        at <ScriptBlock>, C:\Users\avezina\gitrepos\etl.devops.serviceManagement\build.ps1: line 42
                        at <ScriptBlock>, <No file>: line 1
PipelineIterationInfo : {}

Environment data

> $PSVersionTable

Name                           Value                                                                                                                                                                                                                       
----                           -----                                                                                                                                                                                                                       
PSVersion                      5.1.19041.1                                                                                                                                                                                                                 
PSEdition                      Desktop                                                                                                                                                                                                                     
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0...}                                                                                                                                                                                                     
BuildVersion                   10.0.19041.1                                                                                                                                                                                                                
CLRVersion                     4.0.30319.42000                                                                                                                                                                                                             
WSManStackVersion              3.0                                                                                                                                                                                                                         
PSRemotingProtocolVersion      2.3                                                                                                                                                                                                                         
SerializationVersion           1.1.0.1                                                                                                                                                                                                                     


> (Get-Module -ListAvailable PSScriptAnalyzer).Version | ForEach-Object { $_.ToString() }
1.19.0

[rjmholt]

From #1538 (comment).

Here's the relevant code:

PSScriptAnalyzer/Rules/UseShouldProcessCorrectly.cs

Lines 344 to 398 in d04c039

	/// <summary>
	/// Attempt to find whether a function has SupportsShouldProcess set based on its AST.
	/// </summary>
	/// <param name="functionInfo">The function info object referring to the function.</param>
	/// <param name="hasShouldProcessSet">True if SupportsShouldProcess is set, false if not. Value is not valid if this method returns false.</param>
	/// <returns>True if a value for SupportsShouldProcess was found, false otherwise.</returns>
	private bool TryGetShouldProcessValueFromAst(FunctionInfo functionInfo, out bool hasShouldProcessSet)
	{
	// Get the body of the function
	ScriptBlockAst functionBodyAst = (ScriptBlockAst)functionInfo.ScriptBlock.Ast.Find(ast => ast is ScriptBlockAst, searchNestedScriptBlocks: false);
	// Go through attributes on the parameter block, since this is where [CmdletBinding()] will be
	foreach (AttributeAst attributeAst in functionBodyAst.ParamBlock.Attributes)
	{
	// We're looking for [CmdletBinding()]
	if (!attributeAst.TypeName.FullName.Equals("CmdletBinding", StringComparison.OrdinalIgnoreCase))
	{
	continue;
	}
	foreach (NamedAttributeArgumentAst namedArgumentAst in attributeAst.NamedArguments)
	{
	// We want [CmdletBinding(SupportsShouldProcess)]
	if (!namedArgumentAst.ArgumentName.Equals("SupportsShouldProcess", StringComparison.OrdinalIgnoreCase))
	{
	continue;
	}
	// [CmdletBinding(SupportsShouldProcess)] is the same as [CmdletBinding(SupportsShouldProcess = $true)]
	if (namedArgumentAst.ExpressionOmitted)
	{
	hasShouldProcessSet = true;
	return true;
	}
	// Otherwise try to get the value assigned to the parameter, and assume false if value cannot be determined
	try
	{
	hasShouldProcessSet = LanguagePrimitives.IsTrue(
	Helper.GetSafeValueFromExpressionAst(
	namedArgumentAst.Argument));
	}
	catch
	{
	hasShouldProcessSet = false;
	}
	return true;
	}
	}
	hasShouldProcessSet = false;
	return false;
	}

[avezinaATastus]

After looking at my version control,

• June 29th
  • My Machine : Doesn't work today (pretty sure it worked back then)
  • AzureDevOps Pipeline (windows-latest) : Works
• July 5th
  • My Machine : Doesn't work
  • AzureDevOps Pipeline (windows-latest) : Worked

EDIT : I wasn't analyzing checked-in code. ignore this comment.

[avezinaATastus]

Using 1.18.0, I have better details about the error, I think.

writeErrorStream      : True
PSMessageDetails      :
Exception             : System.Management.Automation.RuntimeException: The following exception occurred while constructing the attribute "ServerTransformAttribute": "Value cannot be null.
                        Parameter name: key" ---> System.ArgumentNullException: Value cannot be null.
                        Parameter name: key
                           at System.ThrowHelper.ThrowArgumentNullException(ExceptionArgument argument)
                           at System.Runtime.CompilerServices.ConditionalWeakTable`2.TryGetValue(TKey key, TValue& value)
                           at ServerTransformAttribute..ctor()
                           at CallSite.Target(Closure , CallSite , Object )
                           at System.Dynamic.UpdateDelegates.UpdateAndExecute1[T0,TRet](CallSite site, T0 arg0)
                           --- End of inner exception stack trace ---
                           at System.Management.Automation.Language.Compiler.GetAttribute(AttributeAst attributeAst)
                           at System.Management.Automation.Language.Compiler.GetRuntimeDefinedParameter(ParameterAst parameterAst, Boolean& customParameterSet, Boolean& usesCmdletBinding)
                           at System.Management.Automation.Language.Compiler.GetParameterMetaData(ReadOnlyCollection`1 parameters, Boolean automaticPositions, Boolean& usesCmdletBinding)
                           at System.Management.Automation.CompiledScriptBlockData.InitializeMetadata()
                           at System.Management.Automation.ScriptBlock.get_Attributes()
                           at Microsoft.Windows.PowerShell.ScriptAnalyzer.BuiltinRules.UseShouldProcessCorrectly.SupportsShouldProcess(String cmdName)
                           at Microsoft.Windows.PowerShell.ScriptAnalyzer.BuiltinRules.UseShouldProcessCorrectly.CheckForSupportShouldProcess()
                           at Microsoft.Windows.PowerShell.ScriptAnalyzer.BuiltinRules.UseShouldProcessCorrectly.<AnalyzeScript>d__7.MoveNext()
                           at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
                           at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
                           at Microsoft.Windows.PowerShell.ScriptAnalyzer.ScriptAnalyzer.<>c__DisplayClass83_1.<AnalyzeSyntaxTree>b__2()
TargetObject          : C:\Users\avezina\gitrepos\etl.devops.serviceManagement\Output\ServiceManagement\0.6.2\Public\Update-mdbDeployment.ps1
CategoryInfo          : InvalidOperation: (C:\Users\avezin...bDeployment.ps1:String) [Invoke-ScriptAnalyzer], RuntimeException
FullyQualifiedErrorId : RULE_ERROR,Microsoft.Windows.PowerShell.ScriptAnalyzer.Commands.InvokeScriptAnalyzerCommand
ErrorDetails          :
InvocationInfo        : System.Management.Automation.InvocationInfo
ScriptStackTrace      : at <ScriptBlock>, <No file>: line 1
PipelineIterationInfo : {0, 1}

ServerTransformAttribute is a ArgumentTransformationAttribute derived class. I have two other very similar.

[avezinaATastus]

I tried doing that function TryGetShouldProcessValueFromAst in powershell, and I did not have a problem.

**********************
Windows PowerShell transcript start
Start time: 20200708104529
Username: \avezina
RunAs User: \avezina
Configuration Name: 
Machine: PC-INFO3 (Microsoft Windows NT 10.0.19041.0)
Host Application: powershell.exe
Process ID: 15884
PSVersion: 5.1.19041.1
PSEdition: Desktop
PSCompatibleVersions: 1.0, 2.0, 3.0, 4.0, 5.0, 5.1.19041.1
BuildVersion: 10.0.19041.1
CLRVersion: 4.0.30319.42000
WSManStackVersion: 3.0
PSRemotingProtocolVersion: 2.3
SerializationVersion: 1.1.0.1
**********************
Transcript started, output file is ./test
~\Downloads\0.6.2

➜

PS>$tokens = $Errors = $null
~\Downloads\0.6.2

➜

PS>$ast = [System.Management.Automation.Language.Parser]::ParseInput(${Function:Get-mdbServer}, [ref]$tokens, [ref]$Errors)
~\Downloads\0.6.2

➜

PS>foreach ($attributeast in $ast.ParamBlock.Attributes) {
    if (-not $attributeast.TypeName.FullName -eq 'CmdletBinding') { continue }
    
    foreach ($namedargumentast in $attributeast.NamedArguments) {
        if (-not $namedargumentast.ArgumentName -eq 'SupportsShouldProcess') { continue }
        if ($namedargumentast.ExpressionOmitted) {
            $hasShouldProcessSet = $true
            return $true
        }
        try {
            $hasShouldProcessSet = $namedargumentast.Argument -eq [bool]::TrueString
        } catch {
            $hasShouldProcessSet = $false
        }
        return $true
    }
    
}
True
~\Downloads\0.6.2

➜

PS>$hasShouldProcessSet
False
~\Downloads\0.6.2

➜

PS>Stop-Transcript
**********************
Windows PowerShell transcript end
End time: 20200708104550
**********************

[rjmholt]

I suspect the error you're seeing in 1.18 was fixed in #1397.

I would be nice to work out what's causing the NRE here though.

Does this happen consistently, and if so, can you pinpoint a change in your own script that causes it? If you roll back to a particular script change, does this error stop occurring?

[avezinaATastus]

Here is the weird thing now :
I went back to my June 29 commit. ( before implementing my three ArgumentTransformationAttribute derived class ( [Server | Service | Environment]TransformAttribute ) )
And I am getting an error using 1.18.0 and 1.19.0

writeErrorStream      : True
PSMessageDetails      : 
Exception             : System.Management.Automation.RuntimeException: The following exception occurred while 
                        constructing the attribute "EnvironmentTransformAttribute": "Value cannot be null.
                        Parameter name: key" ---> System.ArgumentNullException: Value cannot be null.
                        Parameter name: key
                           at System.ThrowHelper.ThrowArgumentNullException(ExceptionArgument argument)
                           at System.Runtime.CompilerServices.ConditionalWeakTable`2.TryGetValue(TKey key, TValue& 
                        value)
                           at EnvironmentTransformAttribute..ctor()
                           at CallSite.Target(Closure , CallSite , Object )
                           at System.Dynamic.UpdateDelegates.UpdateAndExecute1[T0,TRet](CallSite site, T0 arg0)
                           --- End of inner exception stack trace ---
                           at System.Management.Automation.Language.Compiler.GetAttribute(AttributeAst attributeAst)
                           at System.Management.Automation.Language.Compiler.GetRuntimeDefinedParameter(ParameterAst 
                        parameterAst, Boolean& customParameterSet, Boolean& usesCmdletBinding)
                           at 
                        System.Management.Automation.Language.Compiler.GetParameterMetaData(ReadOnlyCollection`1 
                        parameters, Boolean automaticPositions, Boolean& usesCmdletBinding)
                           at System.Management.Automation.CompiledScriptBlockData.InitializeMetadata()
                           at System.Management.Automation.ScriptBlock.get_Attributes()
                           at Microsoft.Windows.PowerShell.ScriptAnalyzer.BuiltinRules.UseShouldProcessCorrectly.Suppo
                        rtsShouldProcess(String cmdName)
                           at Microsoft.Windows.PowerShell.ScriptAnalyzer.BuiltinRules.UseShouldProcessCorrectly.Check
                        ForSupportShouldProcess()
                           at Microsoft.Windows.PowerShell.ScriptAnalyzer.BuiltinRules.UseShouldProcessCorrectly.<Anal
                        yzeScript>d__7.MoveNext()
                           at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
                           at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
                           at Microsoft.Windows.PowerShell.ScriptAnalyzer.ScriptAnalyzer.<>c__DisplayClass83_1.<Analyz
                        eSyntaxTree>b__2()
TargetObject          : C:\Users\avezina\gitrepos\etl.devops.serviceManagement\Output\ServiceManagement\0.4.0\Public\U
                        pdate-mdbDeployment.ps1
CategoryInfo          : InvalidOperation: (C:\Users\avezin...bDeployment.ps1:String) [Invoke-ScriptAnalyzer], 
                        RuntimeException
FullyQualifiedErrorId : RULE_ERROR,Microsoft.Windows.PowerShell.ScriptAnalyzer.Commands.InvokeScriptAnalyzerCommand
ErrorDetails          : 
InvocationInfo        : System.Management.Automation.InvocationInfo
ScriptStackTrace      : at <ScriptBlock>, <No file>: line 1
PipelineIterationInfo : {0, 1}

I'm currently not sure if I was always analyzing (but my runs in Azure DevOps seems to) but I will try to check.

The two 'big' changes in my code since the 29th is "PSTypeNames implementation and formatting" and the argument transformation I finished sunday.

[rjmholt]

It looks like PowerShell is trying to reconstruct your attribute and is unable to because one of the parameters required to construct it is null. Are you sure you're using your attribute right?

It seems like PSScriptAnalyzer needs to protect itself here -- we should add a try/catch around the Attributes property reference allowing us to just skip the attributes. Because PowerShell throws here when accessing all attributes, it means we can't selectively skip over attributes, but that's just how things are I think.

[avezinaATastus]

I tried to clean up my PS environment in VSCode. Went back even earlier and uninstalled PSSA 1.18.0

My module : no more ArgumentTransformationAttributes, no more pstypenames.

Made also sure that I don't use SupportsShouldProcess anywhere (not needed for now)

I am back to the NRE.

[rjmholt]

I am back to the NRE.

The original one that you reported in the description? Does it happen every time you run PSSA?

[avezinaATastus]

yes
yes

I can privately send my zipped module, if you'd like.

[rjmholt]

Yeah I think that's the right next step. Can you send it through to psscriptanalyzer@microsoft.com