File: src\Workspaces\SharedUtilitiesAndExtensions\Workspace\VisualBasic\Extensions\ParameterSyntaxExtensions.vb
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Project: src\src\CodeStyle\VisualBasic\CodeFixes\Microsoft.CodeAnalysis.VisualBasic.CodeStyle.Fixes.vbproj (Microsoft.CodeAnalysis.VisualBasic.CodeStyle.Fixes)
' Licensed to the .NET Foundation under one or more agreements.
' The .NET Foundation licenses this file to you under the MIT license.
' See the LICENSE file in the project root for more information.
 
Imports System.Runtime.CompilerServices
Imports Microsoft.CodeAnalysis.VisualBasic.Syntax
Imports Microsoft.CodeAnalysis.VisualBasic.Utilities
Imports System.Threading
 
Namespace Microsoft.CodeAnalysis.VisualBasic.Extensions
    Friend Module ParameterSyntaxExtensions
        <Extension()>
        Public Function CanRemoveAsClause(parameter As ParameterSyntax, semanticModel As SemanticModel, cancellationToken As CancellationToken) As Boolean
            If parameter.AsClause IsNot Nothing AndAlso
                parameter.IsParentKind(SyntaxKind.ParameterList) AndAlso
                parameter.Parent.Parent.IsKind(SyntaxKind.FunctionLambdaHeader, SyntaxKind.SubLambdaHeader) Then
 
                Dim annotation = New SyntaxAnnotation()
                Dim newParameterSyntax = parameter.WithAsClause(Nothing).WithAdditionalAnnotations(annotation)
                Dim oldLambda = parameter.FirstAncestorOrSelf(Of LambdaExpressionSyntax)()
                Dim newLambda = oldLambda.ReplaceNode(parameter, newParameterSyntax)
                Dim speculationAnalyzer = New SpeculationAnalyzer(oldLambda, newLambda, semanticModel, cancellationToken)
                newParameterSyntax = speculationAnalyzer.ReplacedExpression.GetAnnotatedNodes(Of ParameterSyntax)(annotation).First()
 
                Dim oldSymbol = semanticModel.GetDeclaredSymbol(parameter, cancellationToken)
                Dim newSymbol = speculationAnalyzer.SpeculativeSemanticModel.GetDeclaredSymbol(newParameterSyntax, cancellationToken)
                If oldSymbol IsNot Nothing AndAlso
                    newSymbol IsNot Nothing AndAlso
                    Equals(oldSymbol.Type, newSymbol.Type) Then
 
                    Return Not speculationAnalyzer.ReplacementChangesSemantics()
                End If
            End If
 
            Return False
        End Function
    End Module
End Namespace