public static void AnalyzeAddExpression(SyntaxNodeAnalysisContext context)
{
var addExpression = (BinaryExpressionSyntax)context.Node;
if (addExpression.ContainsDiagnostics)
{
return;
}
IMethodSymbol methodSymbol = context.SemanticModel.GetMethodSymbol(addExpression, context.CancellationToken);
if (!SymbolUtility.IsStringAdditionOperator(methodSymbol))
{
return;
}
ExpressionSyntax expression = GetObjectExpression()?.WalkDownParentheses();
if (expression == null)
{
return;
}
if (expression.Kind() == SyntaxKind.AddExpression)
{
return;
}
ITypeSymbol typeSymbol = context.SemanticModel.GetTypeSymbol(expression, context.CancellationToken);
if (typeSymbol?.IsValueType != true)
{
return;
}
DiagnosticHelpers.ReportDiagnostic(context, DiagnosticDescriptors.AvoidBoxingOfValueType, expression);
ExpressionSyntax GetObjectExpression()
{
ImmutableArray <IParameterSymbol> parameters = methodSymbol.Parameters;
if (parameters[0].Type.SpecialType == SpecialType.System_Object)
{
return(addExpression.Left);
}
else if (parameters[1].Type.SpecialType == SpecialType.System_Object)
{
return(addExpression.Right);
}
else
{
return(null);
}
}
}
public static bool IsStringConcatenation(BinaryExpressionSyntax addExpression, SemanticModel semanticModel, CancellationToken cancellationToken = default(CancellationToken))
{
return(addExpression.Kind() == SyntaxKind.AddExpression &&
SymbolUtility.IsStringAdditionOperator(semanticModel.GetMethodSymbol(addExpression, cancellationToken)));
}
public static bool IsFixable(
SimpleMemberInvocationExpressionInfo invocationInfo,
SemanticModel semanticModel,
CancellationToken cancellationToken = default(CancellationToken))
{
if (invocationInfo.Expression.Kind() == SyntaxKind.BaseExpression)
{
return(false);
}
InvocationExpressionSyntax invocationExpression = invocationInfo.InvocationExpression;
IMethodSymbol methodSymbol = semanticModel.GetMethodSymbol(invocationExpression, cancellationToken);
if (SymbolUtility.IsPublicInstanceNonGeneric(methodSymbol, "ToString") &&
methodSymbol.ReturnType.SpecialType == SpecialType.System_String &&
!methodSymbol.Parameters.Any())
{
INamedTypeSymbol containingType = methodSymbol.ContainingType;
if (containingType?.IsReferenceType == true &&
containingType.SpecialType != SpecialType.System_Enum)
{
if (containingType.SpecialType == SpecialType.System_String)
{
return(true);
}
ExpressionSyntax expression = invocationExpression.WalkUpParentheses();
SyntaxNode parent = expression.Parent;
if (parent != null)
{
SyntaxKind kind = parent.Kind();
if (kind == SyntaxKind.Interpolation)
{
return(IsNotHidden(methodSymbol, containingType));
}
else if (kind == SyntaxKind.AddExpression)
{
if (!parent.ContainsDiagnostics &&
IsNotHidden(methodSymbol, containingType))
{
var addExpression = (BinaryExpressionSyntax)expression.Parent;
if (CSharpUtility.IsStringConcatenation(addExpression, semanticModel, cancellationToken))
{
BinaryExpressionSyntax newAddExpression = addExpression.ReplaceNode(expression, invocationInfo.Expression);
IMethodSymbol speculativeSymbol = semanticModel.GetSpeculativeMethodSymbol(addExpression.SpanStart, newAddExpression);
return(SymbolUtility.IsStringAdditionOperator(speculativeSymbol));
}
}
}
}
}
}
return(false);
}