Listing 10.15

Listing 10.15.cs

public IEnumerable<CodeIssue> GetIssues(IDocument document, CommonSyntaxNode node, CancellationToken cancellationToken)
{
    if (node.GetType() != typeof(LocalDeclarationStatementSyntax)) return null;
    var localDeclaration = (LocalDeclarationStatementSyntax)node;
    var semanticModel = document.GetSemanticModel(cancellationToken);
    var containingBlock = localDeclaration.FirstAncestorOrSelf<BlockSyntax>();
    if (containingBlock == null) return null;

    var dataFlowAnalysis = semanticModel.AnalyzeDataFlow(containingBlock);
    var variable = localDeclaration.Declaration.Variables.First();
    var symbol = semanticModel.GetDeclaredSymbol(variable);

    if (dataFlowAnalysis.ReadInside.Contains(symbol)) return null;

    return new[] { new CodeIssue(CodeIssueKind.Warning, localDeclaration.Span, string.Format("Variable {0} is declared but never used", variable.Identifier)) };
}