Handle missing explicit : UserControl

Fix #302

Author: JohanLarsson

WpfAnalyzers.Test/WPF0015RegisteredOwnerTypeMustBeDependencyObjectTests/Valid.cs

@@ -287,4 +287,36 @@ public static int GetBar(DependencyObject element)
 
         RoslynAssert.Valid(Analyzer, code);
     }
+
+    [Test]
+    public static void Issue302()
+    {
+        var code = @"
+namespace N
+{
+    using System.Windows;
+    using System.Windows.Controls;
+
+    public class FooControl
+    {
+        public static readonly DependencyProperty BarProperty = DependencyProperty.Register(
+            ""Bar"",
+            typeof(int),
+            typeof(FooControl),
+            new PropertyMetadata(default(int)));
+
+        public FooControl()
+        {
+            this.InitializeComponent();
+        }
+
+        public int Bar
+        {
+            get { return (int)GetValue(BarProperty); }
+            set { SetValue(BarProperty, value); }
+        }
+    }
+}";
+        RoslynAssert.NoAnalyzerDiagnostics(Analyzer, code);
+    }
 }

WpfAnalyzers/WPF0015RegisteredOwnerTypeMustBeDependencyObject.cs

@@ -1,7 +1,9 @@
 namespace WpfAnalyzers;
 
 using System.Collections.Immutable;
+
 using Gu.Roslyn.AnalyzerExtensions;
+
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.CSharp;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
@@ -44,9 +46,29 @@ private static void Handle(SyntaxNodeAnalysisContext context)
     private static void HandleArgument(SyntaxNodeAnalysisContext context, ArgumentSyntax argument)
     {
         if (argument.TryGetTypeofValue(context.SemanticModel, context.CancellationToken, out var ownerType) &&
-            !ownerType.IsAssignableTo(KnownSymbols.DependencyObject, context.SemanticModel.Compilation))
+            !ownerType.IsAssignableTo(KnownSymbols.DependencyObject, context.SemanticModel.Compilation) &&
+            !IsUserControl())
         {
             context.ReportDiagnostic(Diagnostic.Create(Descriptors.WPF0015RegisteredOwnerTypeMustBeDependencyObject, argument.GetLocation(), KnownSymbols.DependencyProperty.RegisterAttached.Name));
         }
+
+        bool IsUserControl() => context.Node.FirstAncestor<ClassDeclarationSyntax>() is { } classDeclaration &&
+                                !classDeclaration.Modifiers.Any(SyntaxKind.StaticKeyword) &&
+                                classDeclaration.TryFindConstructor(x => x.ParameterList.Parameters.Count == 0, out var ctor) &&
+                                InvokesInitializeComponent(ctor);
+
+        bool InvokesInitializeComponent(ConstructorDeclarationSyntax ctor)
+        {
+            using var walker = Gu.Roslyn.AnalyzerExtensions.InvocationWalker.Borrow(ctor);
+            foreach (var candidate in walker.Invocations)
+            {
+                if (candidate.MethodName() == "InitializeComponent")
+                {
+                    return true;
+                }
+            }
+
+            return false;
+        }
     }
 }