Fix S4143: AD0001 NullReferenceException

[Evangelink]

Description

The rule DotNotOverwriteCollectionElements fails with NRE.

StackTrace is:

Warning	AD0001	Analyzer 'SonarAnalyzer.Rules.VisualBasic.DoNotOverwriteCollectionElements' threw an exception of type 'System.NullReferenceException' with message 'Object reference not set to an instance of an object.'.	ConsoleApp1		1	Active	Analyzer 'SonarAnalyzer.Rules.VisualBasic.DoNotOverwriteCollectionElements' threw the following exception:
'Exception occurred with following context:
Compilation: ConsoleApp1
SyntaxTree: C:\Users\Amaury Leve\Source\Repos\ConsoleApp6\ConsoleApp1\Module1.vb
SyntaxNode: C [ExpressionStatementSyntax]@[65..66) (8,0)-(8,1)

System.NullReferenceException: Object reference not set to an instance of an object.
   at SonarAnalyzer.Rules.VisualBasic.DoNotOverwriteCollectionElements.GetFirstArgumentExpression(InvocationExpressionSyntax invocation)
   at SonarAnalyzer.Rules.VisualBasic.DoNotOverwriteCollectionElements.GetIndexOrKey(StatementSyntax statement)
   at SonarAnalyzer.Rules.DoNotOverwriteCollectionElementsBase`1.AnalysisAction(SyntaxNodeAnalysisContext context)
   at SonarAnalyzer.Helpers.DiagnosticAnalyzerContextHelper.<>c__DisplayClass0_0`1.<RegisterSyntaxNodeActionInNonGenerated>b__0(SyntaxNodeAnalysisContext c)
   at SonarAnalyzer.Helpers.SonarAnalysisContext.<>c__DisplayClass21_0`1.<RegisterContextAction>b__0(TContext c)
   at Microsoft.CodeAnalysis.Diagnostics.AnalyzerExecutor.<>c__44`1.<ExecuteSyntaxNodeAction>b__44_0(ValueTuple`2 data)
   at Microsoft.CodeAnalysis.Diagnostics.AnalyzerExecutor.ExecuteAndCatchIfThrows_NoLock[TArg](DiagnosticAnalyzer analyzer, Action`1 analyze, TArg argument, Nullable`1 info)

Repro steps

Module Module1

    Sub Main()
        Dim f1 = New Foo
        Dim f2 = New Foo

        f1.Attributes.Item("Title") = "some text goes here"
        f2.Attributes.Item("Title") = "some other text goes here"
    End Sub

End Module

Class Foo
    Public Attributes As Dictionary(Of String, String)
End Class

Related information

• SonarAnalyzer.VisualBasic 7.10

[Evangelink]

@valhristov Could you try and tell me if you can reproduce the issue? I added the snippet into the unit test class and I haven't had any failure.

[valhristov]

Yes, I can:

Module NullReferenceReproducer
    Sub Main()
        Bar ' AD0001 NullReferenceException in GetFirstArgumentExpression
    End Sub

    Public Sub Bar()
    End Sub
End Module