WPF0073 don't warn when generic

Fix #353

Author: JohanLarsson

ValidCode/Converters/RelayConverter.cs

@@ -0,0 +1,28 @@
+namespace ValidCode.Converters;
+
+using System;
+using System.Windows.Data;
+
+public sealed class RelayConverter<TSource, TResult> : IValueConverter
+{
+    private readonly Func<TSource, TResult> convert;
+
+    public RelayConverter(Func<TSource, TResult> convert)
+    {
+        this.convert = convert;
+    }
+
+    public object? Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
+    {
+        return value switch
+        {
+            TSource source => this.convert(source),
+            _ => throw new ArgumentException($"Expected value of type {typeof(TSource).Name}"),
+        };
+    }
+
+    object IValueConverter.ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
+    {
+        throw new NotSupportedException($"{nameof(RelayConverter<TSource, TResult>)} can only be used in OneWay bindings");
+    }
+}

WpfAnalyzers.Test/WPF0073ConverterDoesNotHaveAttributeUnknownTypes/Valid.cs

@@ -284,4 +284,40 @@ public object Convert(object value, Type targetType, object parameter, CultureIn
 }";
         RoslynAssert.Valid(Analyzer, code);
     }
+
+    [Test]
+    public static void DonNotWarnWhenGeneric()
+    {
+        var code = @"
+namespace ValidCode.Converters;
+
+using System;
+using System.Windows.Data;
+
+public sealed class RelayConverter<TSource, TResult> : IValueConverter
+{
+    private readonly Func<TSource, TResult> convert;
+
+    public RelayConverter(Func<TSource, TResult> convert)
+    {
+        this.convert = convert;
+    }
+
+    public object? Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
+    {
+        return value switch
+        {
+            TSource source => this.convert(source),
+            _ => throw new ArgumentException($""Expected value of type {typeof(TSource).Name}""),
+        };
+    }
+
+    object IValueConverter.ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
+    {
+        throw new NotSupportedException($""{nameof(RelayConverter<TSource, TResult>)} can only be used in OneWay bindings"");
+    }
+}
+";
+        RoslynAssert.Valid(Analyzer, code);
+    }
 }

WpfAnalyzers/Analyzers/ValueConverterAnalyzer.cs

@@ -62,8 +62,7 @@ context.Node is ClassDeclarationSyntax classDeclaration &&
                 {
                     if (ValueConverter.TryGetConversionTypes(classDeclaration, context.SemanticModel, context.CancellationToken, out var sourceType, out var targetType))
                     {
-                        if (sourceType is { } &&
-                            sourceType != QualifiedType.System.Object &&
+                        if (sourceType != QualifiedType.System.Object &&
                             attribute.TryFindArgument(0, "sourceType", out var arg) &&
                             arg.Expression is TypeOfExpressionSyntax sourceTypeOf &&
                             TypeSymbol.TryGet(sourceTypeOf, type, context.SemanticModel, context.CancellationToken, out var argType) &&
@@ -81,7 +80,8 @@ arg.Expression is TypeOfExpressionSyntax targetTypeOf &&
                         }
                     }
                 }
-                else if (!classDeclaration.Modifiers.Any(SyntaxKind.PartialKeyword))
+                else if (!classDeclaration.Modifiers.Any(SyntaxKind.PartialKeyword) &&
+                         !type.IsGenericType)
                 {
                     context.ReportDiagnostic(
                         Diagnostic.Create(