Avoid globally qualifying user defined types

src/Microsoft.AspNetCore.Razor.Language/src/BoundAttributeDescriptorBuilderExtensions.cs

@@ -96,4 +96,14 @@ public static string GetPropertyName(this BoundAttributeParameterDescriptorBuild
 
         return null;
     }
+
+    public static void SetGloballyQualifiedTypeName(this BoundAttributeDescriptorBuilder builder, string globallyQualifiedTypeName)
+    {
+        builder.Metadata[TagHelperMetadata.Common.GloballyQualifiedTypeName] = globallyQualifiedTypeName;
+    }
+
+    public static string GetGloballyQualifiedTypeName(this BoundAttributeDescriptor descriptor)
+    {
+        return descriptor?.Metadata[TagHelperMetadata.Common.GloballyQualifiedTypeName];
+    }
 }

src/Microsoft.AspNetCore.Razor.Language/src/Components/ComponentDesignTimeNodeWriter.cs

@@ -714,7 +714,15 @@ private void WriteComponentAttributeInnards(CodeRenderingContext context, Compon
                 {
                     context.CodeWriter.Write(ComponentsApi.RuntimeHelpers.TypeCheck);
                     context.CodeWriter.Write("<");
-                    TypeNameHelper.WriteGloballyQualifiedName(context.CodeWriter, node.TypeName);
+                    var explicitType = (bool?)node.Annotations[ComponentMetadata.Component.ExplicitTypeNameKey];
+                    if (explicitType == true)
+                    {
+                        context.CodeWriter.Write(node.TypeName);
+                    }
+                    else
+                    {
+                        TypeNameHelper.WriteGloballyQualifiedName(context.CodeWriter, node.TypeName);
+                    }
                     context.CodeWriter.Write(">");
                     context.CodeWriter.Write("(");
                 }

src/Microsoft.AspNetCore.Razor.Language/src/Components/ComponentGenericTypePass.cs

@@ -337,11 +337,11 @@ private void RewriteTypeNames(TypeNameRewriter rewriter, ComponentIntermediateNo
 
             foreach (var attribute in node.Attributes)
             {
-                string globallyQualifiedTypeName = null;
+                var globallyQualifiedTypeName = attribute.BoundAttribute.GetGloballyQualifiedTypeName();
 
                 if (attribute.TypeName != null)
                 {
-                    globallyQualifiedTypeName = rewriter.Rewrite(attribute.TypeName);
+                    globallyQualifiedTypeName = rewriter.Rewrite(globallyQualifiedTypeName ?? attribute.TypeName);
                     attribute.GloballyQualifiedTypeName = globallyQualifiedTypeName;
                 }
 
@@ -350,6 +350,18 @@ private void RewriteTypeNames(TypeNameRewriter rewriter, ComponentIntermediateNo
                     // If we know the type name, then replace any generic type parameter inside it with
                     // the known types.
                     attribute.TypeName = globallyQualifiedTypeName;
+                    // This is a special case in which we are dealing with a property TItem.
+                    // Given that TItem can have been defined explicitly by the user to a partially
+                    // qualified type, (like MyType), we check if the globally qualified type name
+                    // contains "global::" which will be the case in all cases as we've computed
+                    // this information from the Roslyn symbol except for when the symbol is a generic
+                    // type parameter. In which case, we mark it with an additional annotation to
+                    // acount for that during code generation and avoid trying to fully qualify
+                    // the type name.
+                    if (!globallyQualifiedTypeName.StartsWith("global::", StringComparison.Ordinal))
+                    {
+                        attribute.Annotations.Add(ComponentMetadata.Component.ExplicitTypeNameKey, true);
+                    }
                 }
                 else if (attribute.TypeName == null && (attribute.BoundAttribute?.IsDelegateProperty() ?? false))
                 {

src/Microsoft.AspNetCore.Razor.Language/src/Components/ComponentMetadata.cs

@@ -101,6 +101,8 @@ public static class Component
 
         public const string GenericTypedKey = "Components.GenericTyped";
 
+        public const string ExplicitTypeNameKey = "Components.ExplicitTypeName";
+
         public const string TypeParameterKey = "Components.TypeParameter";
 
         public const string TypeParameterIsCascadingKey = "Components.TypeParameterIsCascading";

src/Microsoft.AspNetCore.Razor.Language/src/Components/ComponentNodeWriter.cs

@@ -294,7 +294,7 @@ protected List<TypeInferenceMethodParameter> GetTypeInferenceMethodParameters(Co
                     typeName = attribute.TypeName;
                     if (attribute.BoundAttribute != null && !attribute.BoundAttribute.IsGenericTypedProperty())
                     {
-                        typeName = "global::" + typeName;
+                        typeName = typeName.StartsWith("global::", StringComparison.Ordinal) ? typeName : $"global::{typeName}";
                     }
                 }
 

src/Microsoft.AspNetCore.Razor.Language/src/Components/ComponentRuntimeNodeWriter.cs

@@ -653,7 +653,15 @@ private void WriteComponentAttributeInnards(CodeRenderingContext context, Compon
                 {
                     context.CodeWriter.Write(ComponentsApi.RuntimeHelpers.TypeCheck);
                     context.CodeWriter.Write("<");
-                    TypeNameHelper.WriteGloballyQualifiedName(context.CodeWriter, node.TypeName);
+                    var explicitType = (bool?)node.Annotations[ComponentMetadata.Component.ExplicitTypeNameKey];
+                    if (explicitType == true)
+                    {
+                        context.CodeWriter.Write(node.TypeName);
+                    }
+                    else
+                    {
+                        TypeNameHelper.WriteGloballyQualifiedName(context.CodeWriter, node.TypeName);
+                    }
                     context.CodeWriter.Write(">");
                     context.CodeWriter.Write("(");
                 }

src/Microsoft.AspNetCore.Razor.Language/src/TagHelperMetadata.cs

@@ -1,4 +1,4 @@
-// Licensed to the .NET Foundation under one or more agreements.
+// Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
 #nullable disable
@@ -13,6 +13,8 @@ public static class Common
 
         public static readonly string TypeName = "Common.TypeName";
 
+        public static readonly string GloballyQualifiedTypeName = "Common.GloballyQualifiedTypeName";
+
         public static readonly string ClassifyAttributesOnly = "Common.ClassifyAttributesOnly";
     }
 

src/Microsoft.AspNetCore.Razor.Language/test/IntegrationTests/ComponentCodeGenerationTestBase.cs

@@ -3710,6 +3710,36 @@ public class MyComponent<TItem> : ComponentBase
         CompileToAssembly(generated);
     }
 
+    [Fact]
+    public void GenericComponent_NonPrimitiveType()
+    {
+        // Arrange
+        AdditionalSyntaxTrees.Add(Parse(@"
+using Microsoft.AspNetCore.Components;
+
+namespace Test
+{
+    public class MyComponent<TItem> : ComponentBase
+    {
+        [Parameter] public TItem Item { get; set; }
+    }
+
+    public class CustomType
+    {
+    }
+}
+"));
+
+        // Act
+        var generated = CompileToCSharp(@"
+<MyComponent TItem=""CustomType"" Item=""new CustomType()""/>");
+
+        // Assert
+        AssertDocumentNodeMatchesBaseline(generated.CodeDocument);
+        AssertCSharpDocumentMatchesBaseline(generated.CodeDocument);
+        CompileToAssembly(generated);
+    }
+
     [Fact]
     public void ChildComponent_Generic_TypeInference()
     {

src/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentDesignTimeCodeGenerationTest/GenericComponent_NonPrimitiveType/TestComponent.codegen.cs

@@ -0,0 +1,55 @@
+// <auto-generated/>
+#pragma warning disable 1591
+namespace Test
+{
+    #line hidden
+    using System;
+    using System.Collections.Generic;
+    using System.Linq;
+    using System.Threading.Tasks;
+    using Microsoft.AspNetCore.Components;
+    public partial class TestComponent : global::Microsoft.AspNetCore.Components.ComponentBase
+    {
+        #pragma warning disable 219
+        private void __RazorDirectiveTokenHelpers__() {
+        }
+        #pragma warning restore 219
+        #pragma warning disable 0414
+        private static System.Object __o = null;
+        #pragma warning restore 0414
+        #pragma warning disable 1998
+        protected override void BuildRenderTree(global::Microsoft.AspNetCore.Components.Rendering.RenderTreeBuilder __builder)
+        {
+            __o = typeof(
+#nullable restore
+#line 1 "x:\dir\subdir\Test\TestComponent.cshtml"
+                    CustomType
+
+#line default
+#line hidden
+#nullable disable
+            );
+            __o = global::Microsoft.AspNetCore.Components.CompilerServices.RuntimeHelpers.TypeCheck<CustomType>(
+#nullable restore
+#line 1 "x:\dir\subdir\Test\TestComponent.cshtml"
+                                      new CustomType()
+
+#line default
+#line hidden
+#nullable disable
+            );
+            __builder.AddAttribute(-1, "ChildContent", (global::Microsoft.AspNetCore.Components.RenderFragment)((__builder2) => {
+            }
+            ));
+#nullable restore
+#line 1 "x:\dir\subdir\Test\TestComponent.cshtml"
+__o = typeof(global::Test.MyComponent<>);
+
+#line default
+#line hidden
+#nullable disable
+        }
+        #pragma warning restore 1998
+    }
+}
+#pragma warning restore 1591

src/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentDesignTimeCodeGenerationTest/GenericComponent_NonPrimitiveType/TestComponent.ir.txt

@@ -0,0 +1,21 @@
+Document - 
+    NamespaceDeclaration -  - Test
+        UsingDirective - (3:1,1 [12] ) - System
+        UsingDirective - (18:2,1 [32] ) - System.Collections.Generic
+        UsingDirective - (53:3,1 [17] ) - System.Linq
+        UsingDirective - (73:4,1 [28] ) - System.Threading.Tasks
+        UsingDirective - (104:5,1 [37] ) - Microsoft.AspNetCore.Components
+        ClassDeclaration -  - public partial - TestComponent - global::Microsoft.AspNetCore.Components.ComponentBase - 
+            DesignTimeDirective - 
+            CSharpCode - 
+                IntermediateToken -  - CSharp - #pragma warning disable 0414
+            CSharpCode - 
+                IntermediateToken -  - CSharp - private static System.Object __o = null;
+            CSharpCode - 
+                IntermediateToken -  - CSharp - #pragma warning restore 0414
+            MethodDeclaration -  - protected override - void - BuildRenderTree
+                Component - (0:0,0 [57] x:\dir\subdir\Test\TestComponent.cshtml) - MyComponent
+                    ComponentTypeArgument - (20:0,20 [10] x:\dir\subdir\Test\TestComponent.cshtml) - TItem
+                        LazyIntermediateToken - (20:0,20 [10] x:\dir\subdir\Test\TestComponent.cshtml) - CSharp - CustomType
+                    ComponentAttribute - (38:0,38 [16] x:\dir\subdir\Test\TestComponent.cshtml) - Item - Item - AttributeStructure.DoubleQuotes
+                        LazyIntermediateToken - (38:0,38 [16] x:\dir\subdir\Test\TestComponent.cshtml) - CSharp - new CustomType()

src/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentDesignTimeCodeGenerationTest/GenericComponent_NonPrimitiveType/TestComponent.mappings.txt

@@ -0,0 +1,10 @@
+Source Location: (20:0,20 [10] x:\dir\subdir\Test\TestComponent.cshtml)
+|CustomType|
+Generated Location: (915:25,20 [10] )
+|CustomType|
+
+Source Location: (38:0,38 [16] x:\dir\subdir\Test\TestComponent.cshtml)
+|new CustomType()|
+Generated Location: (1215:34,38 [16] )
+|new CustomType()|
+

src/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentRuntimeCodeGenerationTest/GenericComponent_NonPrimitiveType/TestComponent.codegen.cs

@@ -0,0 +1,31 @@
+// <auto-generated/>
+#pragma warning disable 1591
+namespace Test
+{
+    #line hidden
+    using System;
+    using System.Collections.Generic;
+    using System.Linq;
+    using System.Threading.Tasks;
+    using Microsoft.AspNetCore.Components;
+    public partial class TestComponent : global::Microsoft.AspNetCore.Components.ComponentBase
+    {
+        #pragma warning disable 1998
+        protected override void BuildRenderTree(global::Microsoft.AspNetCore.Components.Rendering.RenderTreeBuilder __builder)
+        {
+            __builder.OpenComponent<global::Test.MyComponent<CustomType>>(0);
+            __builder.AddAttribute(1, "Item", global::Microsoft.AspNetCore.Components.CompilerServices.RuntimeHelpers.TypeCheck<CustomType>(
+#nullable restore
+#line 1 "x:\dir\subdir\Test\TestComponent.cshtml"
+                                      new CustomType()
+
+#line default
+#line hidden
+#nullable disable
+            ));
+            __builder.CloseComponent();
+        }
+        #pragma warning restore 1998
+    }
+}
+#pragma warning restore 1591

src/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentRuntimeCodeGenerationTest/GenericComponent_NonPrimitiveType/TestComponent.ir.txt

@@ -0,0 +1,14 @@
+Document - 
+    NamespaceDeclaration -  - Test
+        UsingDirective - (3:1,1 [14] ) - System
+        UsingDirective - (18:2,1 [34] ) - System.Collections.Generic
+        UsingDirective - (53:3,1 [19] ) - System.Linq
+        UsingDirective - (73:4,1 [30] ) - System.Threading.Tasks
+        UsingDirective - (104:5,1 [39] ) - Microsoft.AspNetCore.Components
+        ClassDeclaration -  - public partial - TestComponent - global::Microsoft.AspNetCore.Components.ComponentBase - 
+            MethodDeclaration -  - protected override - void - BuildRenderTree
+                Component - (0:0,0 [57] x:\dir\subdir\Test\TestComponent.cshtml) - MyComponent
+                    ComponentTypeArgument - (20:0,20 [10] x:\dir\subdir\Test\TestComponent.cshtml) - TItem
+                        LazyIntermediateToken - (20:0,20 [10] x:\dir\subdir\Test\TestComponent.cshtml) - CSharp - CustomType
+                    ComponentAttribute - (38:0,38 [16] x:\dir\subdir\Test\TestComponent.cshtml) - Item - Item - AttributeStructure.DoubleQuotes
+                        LazyIntermediateToken - (38:0,38 [16] x:\dir\subdir\Test\TestComponent.cshtml) - CSharp - new CustomType()

src/Microsoft.CodeAnalysis.Razor/src/ComponentTagHelperDescriptorProvider.cs

@@ -181,7 +181,7 @@ private void CreateProperty(TagHelperDescriptorBuilder builder, IPropertySymbol
             pb.TypeName = property.Type.ToDisplayString(FullNameTypeDisplayFormat);
             pb.SetPropertyName(property.Name);
             pb.IsEditorRequired = property.GetAttributes().Any(a => a.AttributeClass.ToDisplayString() == "Microsoft.AspNetCore.Components.EditorRequiredAttribute");
-
+            pb.SetGloballyQualifiedTypeName(property.Type.ToDisplayString(GloballyQualifiedFullNameTypeDisplayFormat));
             if (kind == PropertyKind.Enum)
             {
                 pb.IsEnum = true;

src/Microsoft.CodeAnalysis.Razor/src/GlobalQualifiedTypeNameRewriter.cs

@@ -59,7 +59,21 @@ public override SyntaxNode VisitQualifiedName(QualifiedNameSyntax node)
             node = (QualifiedNameSyntax)base.VisitQualifiedName(node);
 
             // Rewriting these is complicated, best to just tostring and parse again.
-            return SyntaxFactory.ParseTypeName("global::" + node.ToString());
+            return SyntaxFactory.ParseTypeName(IsGloballyQualified(node) ? node.ToString() : "global::" + node.ToString());
+
+            static bool IsGloballyQualified(QualifiedNameSyntax node)
+            {
+                var candidate = node;
+                while (candidate != null)
+                {
+                    if (candidate.Left is AliasQualifiedNameSyntax)
+                    {
+                        return true;
+                    }
+                    candidate = candidate.Left as QualifiedNameSyntax;
+                }
+                return false;
+            }
         }
 
         public override SyntaxNode VisitIdentifierName(IdentifierNameSyntax node)

src/Microsoft.CodeAnalysis.Razor/test/ComponentTagHelperDescriptorProviderTest.cs

@@ -131,6 +131,7 @@ public Task SetParametersAsync(ParameterView parameters)
         // which is trivial. Verifying it once in detail and then ignoring it.
         Assert.Collection(
             attribute.Metadata.OrderBy(kvp => kvp.Key),
+            kvp => { Assert.Equal(TagHelperMetadata.Common.GloballyQualifiedTypeName, kvp.Key); Assert.Equal("global::System.String", kvp.Value); },
             kvp => { Assert.Equal(TagHelperMetadata.Common.PropertyName, kvp.Key); Assert.Equal("MyProperty", kvp.Value); });
     }