private static SyntaxNode ApplyFix(SyntaxNode currentRoot, ExpressionSyntax targetNode, ITypeSymbol conversionType)
{
// TODO:
// the Simplifier doesn't remove the redundant cast from the expression
// Issue link: https://github.com/dotnet/roslyn/issues/41500
var castExpression = targetNode.Cast(conversionType).WithAdditionalAnnotations(Simplifier.Annotation);
var newRoot = currentRoot.ReplaceNode(targetNode, castExpression);
return(newRoot);
}
/// <summary>
/// Adds to <paramref name="targetType"/> if it does not contain an anonymous
/// type and binds to the same type at the given <paramref name="position"/>.
/// </summary>
public static ExpressionSyntax CastIfPossible(
this ExpressionSyntax expression,
ITypeSymbol targetType,
int position,
SemanticModel semanticModel,
CancellationToken cancellationToken)
{
if (targetType.ContainsAnonymousType())
{
return(expression);
}
if (targetType.IsSystemVoid())
{
return(expression);
}
if (targetType.Kind == SymbolKind.DynamicType)
{
targetType = semanticModel.Compilation.GetSpecialType(SpecialType.System_Object);
}
var typeSyntax = targetType.GenerateTypeSyntax();
var type = semanticModel.GetSpeculativeTypeInfo(
position,
typeSyntax,
SpeculativeBindingOption.BindAsTypeOrNamespace).Type;
if (!targetType.Equals(type))
{
return(expression);
}
var castExpression = expression.Cast(targetType);
// Ensure that inserting the cast doesn't change the semantics.
var specAnalyzer = new SpeculationAnalyzer(expression, castExpression, semanticModel, cancellationToken);
var speculativeSemanticModel = specAnalyzer.SpeculativeSemanticModel;
if (speculativeSemanticModel == null)
{
return(expression);
}
var speculatedCastExpression = (CastExpressionSyntax)specAnalyzer.ReplacedExpression;
if (!CastSimplifier.IsUnnecessaryCast(speculatedCastExpression, speculativeSemanticModel, cancellationToken))
{
return(expression);
}
return(castExpression);
}