I'm implementing a custom Roslyn Analyzer whose ruleset would override a currently existing rule shipped by default with Visual Studio. Is there some way to make my rule silence this other rule in specific scenarios?
I haven't so far been able to find any documenation on whether this is possible.
Yes! This is possible via implementing a DiagnosticSuppressor, available since Roslyn 3.3.1, that you could add alongside your DiagnosticAnalyzer. Actually, DiagnosticSuppressor derives from DiagnosticAnalyzer, and could look something like this:
[DiagnosticAnalyzer(LanguageNames.CSharp)]
internal sealed class MyDiagnosticSuppressor : DiagnosticSuppressor
{
private static readonly SuppressionDescriptor Rule = new(
"My-Diagnostic-Suppressor-Id",
"Suppressed-Diagnostic-Id",
"Justification / Description."
);
public override ImmutableArray<SuppressionDescriptor> SupportedSuppressions
=> ImmutableArray.Create(Rule);
public override void ReportSuppressions(SuppressionAnalysisContext context)
{
foreach (var diagnostic in context.ReportedDiagnostics)
{
Location location = diagnostic.Location;
SyntaxTree? syntaxTree = location.SourceTree;
SyntaxNode root = syntaxTree.GetRoot(context.CancellationToken);
TextSpan textSpan = location.SourceSpan;
SyntaxNode node = root.FindNode(textSpan);
SemanticModel semanticModel = context.GetSemanticModel(syntaxTree);
if (ShouldSuppress(context.Compilation, semanticModel, node, context.CancellationToken))
{
Suppression suppression = Suppression.Create(Rule, diagnostic);
context.ReportSuppression(suppression);
}
}
}
private static bool ShouldSuppress(Compilation compilation, SemanticModel semanticModel, SyntaxNode node, CancellationToken cancellationToken);
}
Also, I've recently built a DiagnosticSuppressor, which suppresses CA1707 (Identifiers should not contain underscores) on MSTest, NUnit and xUnit.net test methods. Here's that Pull Request, including unit tests and benchmarks. Perhaps it proves useful to you.