Enable nullables and nullable warnings as errors globally

Common/CommunityToolkit.Labs.Core.SourceGenerators/ToolkitSampleOptionGenerator.cs

@@ -83,7 +83,7 @@ namespace {containingClassSymbol.ContainingNamespace}
 {{
     public partial class {containingClassSymbol.Name} : {nameof(System.ComponentModel.INotifyPropertyChanged)}
     {{
-		public event PropertyChangedEventHandler PropertyChanged;
+		public event PropertyChangedEventHandler? PropertyChanged;
     }}
 }}
 ";
@@ -141,7 +141,7 @@ namespace {containingClassSymbol.ContainingNamespace}
     {{
         public {typeName} {propertyName}
         {{
-            get => (({typeName})(({viewModelType.FullName})GeneratedPropertyMetadata!.First(x => x.Name == ""{propertyName}""))!.Value);
+            get => (({typeName})(({viewModelType.FullName})GeneratedPropertyMetadata!.First(x => x.Name == ""{propertyName}""))!.Value!)!;
             set
             {{
 				if (GeneratedPropertyMetadata?.FirstOrDefault(x => x.Name == nameof({propertyName})) is {viewModelType.FullName} metadata)

Common/CommunityToolkit.Labs.Shared/App.xaml.cs

@@ -56,7 +56,7 @@ namespace CommunityToolkit.Labs.Shared
         /// <param name="e">Details about the launch request and process.</param>
         protected override void OnLaunched(LaunchActivatedEventArgs e)
         {
-            Frame rootFrame = null;
+            Frame? rootFrame = null;
 
 #if WINAPPSDK
             var window = new Window();
@@ -88,6 +88,9 @@ namespace CommunityToolkit.Labs.Shared
 #else
             if (e.PrelaunchActivated == false)
             {
+                if (rootFrame is null)
+                    throw new InvalidOperationException("Cannot display app content, root frame is missing.");
+
                 if (rootFrame.Content == null)
                 {
                     rootFrame.Navigate(typeof(AppLoadingView), e.Arguments);

Common/CommunityToolkit.Labs.Shared/AppLoadingView.xaml.cs

@@ -115,7 +115,7 @@ namespace CommunityToolkit.Labs.Shared
         }
 
         // Needed because Frame.Navigate doesn't work inside of the OnNavigatedTo override.
-        private void ScheduleNavigate(Type type, object param = null)
+        private void ScheduleNavigate(Type type, object? param = null)
         {
             DispatcherQueue.GetForCurrentThread().TryEnqueue(() =>
             {

Common/CommunityToolkit.Labs.Shared/CommunityToolkit.Labs.Shared.projitems

@@ -21,6 +21,7 @@
     <Compile Include="$(MSBuildThisFileDirectory)AppLoadingView.xaml.cs">
       <DependentUpon>AppLoadingView.xaml</DependentUpon>
     </Compile>
+    <Compile Include="$(MSBuildThisFileDirectory)Polyfills\System.Runtime.CompilerServices\IsExternalInit.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Renderers\GeneratedSampleOptionsRenderer.xaml.cs">
       <DependentUpon>GeneratedSampleOptionsRenderer.xaml</DependentUpon>
     </Compile>

Common/CommunityToolkit.Labs.Shared/MainPage.xaml.cs

@@ -61,7 +61,7 @@ namespace CommunityToolkit.Labs.Shared
                     NavigationViewItems.Add(item);
             }
 
-           base.OnNavigatedTo(e);
+            base.OnNavigatedTo(e);
         }
 
         private void OnSelectionChanged(NavigationView sender, NavigationViewSelectionChangedEventArgs e)
@@ -83,12 +83,12 @@ namespace CommunityToolkit.Labs.Shared
             foreach (var navData in categoryData)
             {
                 // Make subcategories
-                var subcategoryData = GenerateSubcategoryNavItems(navData.SampleMetadata);
+                var subcategoryData = GenerateSubcategoryNavItems(navData.SampleMetadata ?? Enumerable.Empty<ToolkitSampleMetadata>());
 
                 foreach (var subcategoryItemData in subcategoryData)
                 {
                     // Make samples
-                    var sampleNavigationItems = GenerateSampleNavItems(subcategoryItemData.SampleMetadata);
+                    var sampleNavigationItems = GenerateSampleNavItems(subcategoryItemData.SampleMetadata ?? Enumerable.Empty<ToolkitSampleMetadata>());
 
                     foreach (var item in sampleNavigationItems)
                     {
@@ -123,14 +123,10 @@ namespace CommunityToolkit.Labs.Shared
 
             foreach (var subcategoryGroup in samplesBySubcategory)
             {
-                yield return new GroupNavigationItemData
+                yield return new GroupNavigationItemData(new NavigationViewItem
                 {
-                    NavItem = new NavigationViewItem
-                    {
-                        Content = subcategoryGroup.Key,
-                    },
-                    SampleMetadata = subcategoryGroup.ToArray(),
-                };
+                    Content = subcategoryGroup.Key,
+                }, subcategoryGroup.ToArray());
             }
         }
 
@@ -140,28 +136,15 @@ namespace CommunityToolkit.Labs.Shared
 
             foreach (var categoryGroup in samplesByCategory)
             {
-                yield return new GroupNavigationItemData()
+                yield return new GroupNavigationItemData(new NavigationViewItem
                 {
-                    NavItem = new NavigationViewItem()
-                    {
-                        Content = categoryGroup.Key,
-                    },
-                    SampleMetadata = categoryGroup.ToArray(),
-                };
+                    Content = categoryGroup.Key,
+                }, categoryGroup.ToArray());
             }
         }
 
-        private record GroupNavigationItemData
-        {
-            /// <summary>
-            /// A navigation item to contain items in this group.
-            /// </summary>
-            public NavigationViewItem NavItem { get; set; }
-
-            /// <summary>
-            /// The samples that belong under <see cref="NavItem"/>.
-            /// </summary>
-            public IEnumerable<ToolkitSampleMetadata> SampleMetadata { get; set; }
-        };
+        /// <param name="NavItem">A navigation item to contain items in this group.</param>
+        /// <param name="SampleMetadata">The samples that belong under <see cref="NavItem"/>.</param>
+        private record GroupNavigationItemData(NavigationViewItem NavItem, IEnumerable<ToolkitSampleMetadata> SampleMetadata);
     }
 }

Common/CommunityToolkit.Labs.Shared/Polyfills/System.Runtime.CompilerServices/IsExternalInit.cs

@@ -0,0 +1,16 @@
+#if !NET6_0_OR_GREATER
+
+using System.ComponentModel;
+
+namespace System.Runtime.CompilerServices;
+
+/// <summary>
+/// Reserved to be used by the compiler for tracking metadata.
+/// This class should not be used by developers in source code.
+/// </summary>
+[EditorBrowsable(EditorBrowsableState.Never)]
+internal static class IsExternalInit
+{
+}
+
+#endif

Common/CommunityToolkit.Labs.Shared/Renderers/ToolkitSampleRenderer.xaml.cs

@@ -129,7 +129,7 @@ namespace CommunityToolkit.Labs.Shared.Renderers
             var sampleControlInstance = (UIElement)Metadata.SampleControlFactory();
 
             // Custom control-based sample options.
-            if (Metadata.SampleOptionsPaneType is not null)
+            if (Metadata.SampleOptionsPaneType is not null && Metadata.SampleOptionsPaneFactory is not null)
             {
                 SampleOptionsPaneInstance = (UIElement)Metadata.SampleOptionsPaneFactory(sampleControlInstance);
             }
@@ -182,6 +182,12 @@ namespace CommunityToolkit.Labs.Shared.Renderers
             var simpleAssemblyName = type.Assembly.GetName().Name;
             var typeNamespace = type.Namespace;
 
+            if (string.IsNullOrWhiteSpace(simpleAssemblyName))
+                throw new ArgumentException($"Unable to find assembly name for provided type {type}.", nameof(simpleAssemblyName));
+
+            if (string.IsNullOrWhiteSpace(typeNamespace))
+                throw new ArgumentException($"Unable to find namespace for provided type {type}.", nameof(typeNamespace));
+
             var folderPath = typeNamespace.Replace(simpleAssemblyName, "").Trim('.').Replace('.', '/');
 
             return $"ms-appx:///{simpleAssemblyName}/{folderPath}/{type.Name}";

Directory.Build.props

@@ -3,7 +3,7 @@
     <RepositoryDirectory>$(MSBuildThisFileDirectory)</RepositoryDirectory>
   </PropertyGroup>
 
-  <Import Project="$(RepositoryDirectory)Windows.Toolkit.Common.props" />
+  <Import Project="Windows.Toolkit.Common.props" />
 
   <PropertyGroup>
     <DebugType>Embedded</DebugType>

Labs/CanvasLayout/samples/CanvasLayout.Sample/SampleThree/SamplePage3.xaml.cs

@@ -60,6 +60,6 @@ namespace CanvasLayout.Sample.SampleThree
 
     public class CanvasItem : CanvasLayoutItem
     {
-        public string Text { get; set; }
+        public string Text { get; set; } = string.Empty;
     }
 }

Labs/CanvasLayout/samples/CanvasLayout.Wasm/Program.cs

@@ -6,7 +6,7 @@ namespace CanvasLayout.Wasm
 {
 	public class Program
 	{
-		private static App _app;
+		private static App? _app;
 
 		static int Main(string[] args)
 		{

Labs/CanvasLayout/src/CanvasLayout.cs

@@ -104,20 +104,7 @@ namespace CommunityToolkit.Labs.WinUI
         /// List of layout bounds for items starting with the
         /// FirstRealizedIndex.
         /// </summary>
-        public List<Rect> LayoutRects
-        {
-            get
-            {
-                if (_layoutRects == null)
-                {
-                    _layoutRects = new List<Rect>();
-                }
-
-                return _layoutRects;
-            }
-        }
-
-        private List<Rect> _layoutRects;
+        public List<Rect> LayoutRects { get; } = new List<Rect>();
     }
 
     // TODO: Make DP? Can we do this with property mapping instead?

Platforms/CommunityToolkit.Labs.Wasm/Program.cs

@@ -6,7 +6,7 @@ namespace CommunityToolkit.Labs.Wasm
 {
 	public class Program
 	{
-		private static App _app;
+		private static App? _app;
 
 		static int Main(string[] args)
 		{

Windows.Toolkit.Common.props

@@ -15,7 +15,8 @@
 
   <PropertyGroup>
     <Features>Strict</Features>
-    <Nullable>Disable</Nullable>
+    <Nullable>enable</Nullable>
+    <WarningsAsErrors>nullable</WarningsAsErrors>
     <LangVersion>Latest</LangVersion>
     <DefaultLanguage>en-US</DefaultLanguage>
     <NoPackageAnalysis>true</NoPackageAnalysis>