Do not suggest to use generic event handler (RCS1159) (#1022)

ChangeLog.md

@@ -15,6 +15,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Add/remove blank line after file scoped namespace declaration ([RCS0060](https://github.com/JosefPihrt/Roslynator/blob/main/docs/analyzers/RCS0060.md)) ([#1014](https://github.com/josefpihrt/roslynator/pull/1014)).
 - Do not remove overriding member in record ([RCS1132](https://github.com/JosefPihrt/Roslynator/blob/main/docs/analyzers/RCS1132.md)) ([#1015](https://github.com/josefpihrt/roslynator/pull/1015)).
 - Do not remove parameterless empty constructor in a struct with field initializers ([RCS1074](https://github.com/JosefPihrt/Roslynator/blob/main/docs/analyzers/RCS1074.md)) ([#1020](https://github.com/josefpihrt/roslynator/pull/1020)).
+- Do not suggest to use generic event handler ([RCS1159](https://github.com/JosefPihrt/Roslynator/blob/main/docs/analyzers/RCS1159.md)) ([#1019](https://github.com/josefpihrt/roslynator/pull/1019)).
 
 ## [4.2.0] - 2022-11-27
 

src/Analyzers/CSharp/Analysis/UseGenericEventHandlerAnalyzer.cs

@@ -67,6 +67,9 @@ private static void AnalyzeEvent(SymbolAnalysisContext context)
         if (!parameters[0].Type.IsObject())
             return;
 
+        if (parameters[1].Type.IsRefLikeType)
+            return;
+
         if (eventSymbol.ImplementsInterfaceMember<IEventSymbol>(allInterfaces: true))
             return;
 

src/Tests/Analyzers.Tests/RCS1159UseGenericEventHandlerTests.cs

@@ -206,6 +206,23 @@ void M()
 class FooEventArgs
 {
 }
+");
+    }
+
+    [Fact, Trait(Traits.Analyzer, DiagnosticIdentifiers.UseGenericEventHandler)]
+    public async Task TestNoDiagnostic_EventArgsIsRefStruct()
+    {
+        await VerifyNoDiagnosticAsync(@"
+public delegate void CustomEventHandler(object sender, RefStructEventArgs e);
+
+public readonly ref struct RefStructEventArgs
+{
+}
+
+public interface IEventTest
+{
+    event CustomEventHandler CustomEvent;
+}
 ");
     }
 }