// This is kinda duplicated in CodeBlockAnalyzer.GetAssignmentStatus
private void CheckExpressionForNull(ISymbol symbol, ExpressionSyntax expression, MethodFlowAnalysis analysis = null)
{
var expressionValueType = expression.GetTypeOfValue(context.SemanticModel);
if (expressionValueType == ValueType.NotNull)
{
// Argument cannot be null, so move to the next
return;
}
if (expressionValueType == ValueType.Null)
{
context.ReportDiagnostic(MainAnalyzer.CreateReturnNull(expression.GetLocation(), symbol.ToString()));
return;
}
if (analysis == null)
{
context.ReportDiagnostic(MainAnalyzer.CreateReturnNull(expression.GetLocation(), symbol.ToString()));
return;
}
ExpressionStatus status = analysis.IsAlwaysAssigned(expression, expression);
if (!status.IsAssigned())
{
context.ReportDiagnostic(MainAnalyzer.CreateReturnNull(expression.GetLocation(), symbol.ToString()));
}
if (status == ExpressionStatus.AssignedWithUnneededConstraint)
{
context.ReportDiagnostic(MainAnalyzer.CreateUnneededConstraint(expression.GetLocation(), symbol.ToString()));
}
}
private void ReportIssue(ExpressionStatus status, Location location, string errorContext)
{
switch (status)
{
case ExpressionStatus.NotAssigned:
context.ReportDiagnostic(MainAnalyzer.CreateNullAssignmentError(location, errorContext));
break;
case ExpressionStatus.ReassignedAfterCondition:
context.ReportDiagnostic(MainAnalyzer.CreateAssignmentAfterCondition(location, errorContext));
break;
case ExpressionStatus.AssignedWithUnneededConstraint:
context.ReportDiagnostic(MainAnalyzer.CreateUnneededConstraint(location, errorContext));
break;
}
}
public override void VisitAssignmentExpression(AssignmentExpressionSyntax node)
{
base.VisitAssignmentExpression(node);
var valueType = node.Right.GetTypeOfValue(context.SemanticModel);
if (valueType == ValueType.NotNull)
{
return;
}
var target = node.Left.FindUnderlyingMember();
if (target == null)
{
return;
}
var symbol = context.SemanticModel.GetSymbolInfo(target).Symbol;
if (!symbol.HasNotNullOrCheckNull())
{
return;
}
switch (GetAssignmentStatus(node.Right, node, valueType))
{
case ExpressionStatus.NotAssigned:
context.ReportDiagnostic(MainAnalyzer.CreateNullAssignmentError(node.GetLocation(), symbol));
break;
case ExpressionStatus.ReassignedAfterCondition:
context.ReportDiagnostic(MainAnalyzer.CreateAssignmentAfterCondition(node.GetLocation(), node.ToString()));
break;
case ExpressionStatus.AssignedWithUnneededConstraint:
context.ReportDiagnostic(MainAnalyzer.CreateUnneededConstraint(node.GetLocation(), node.ToString()));
break;
}
}
public override void VisitInvocationExpression(InvocationExpressionSyntax node)
{
base.VisitInvocationExpression(node);
var methodDefinition = context.SemanticModel.GetSymbolInfo(node).Symbol as IMethodSymbol;
if (methodDefinition == null)
{
return;
}
if (node.IsCheckAgainstNull(methodDefinition, out var target, out var valueType))
{
ReportIfIsNotNullSymbol(target);
}
if (methodDefinition.IsConstraintMethod())
{
if (node.IsConstraint(context.SemanticModel, out var expression))
{
var symbol = context.SemanticModel.GetSymbolInfo(expression).Symbol;
if (symbol.HasNotNullOrCheckNull())
{
context.ReportDiagnostic(MainAnalyzer.CreateUnneededConstraint(node.GetLocation(), symbol.ToString()));
}
}
else
{
context.ReportDiagnostic(MainAnalyzer.CreateInvalidConstraintError(node.GetLocation()));
}
}
CheckMethodInvocation(
node,
methodDefinition,
node.ArgumentList,
(status, location, error) => ReportIssue(status, location, error));
}