Handle using global:: when discovering components

src/Compiler/Microsoft.AspNetCore.Razor.Language/src/DefaultRazorTagHelperContextDiscoveryPhase.cs

@@ -355,8 +355,21 @@ internal static bool IsTypeInNamespace(TagHelperDescriptor tagHelper, string @na
 
             static bool IsTypeInNamespace(string typeNamespace, string @namespace)
             {
-                // Either the typeName is not the full type name or this type is at the top level.
-                return string.IsNullOrEmpty(typeNamespace) || typeNamespace.Equals(@namespace, StringComparison.Ordinal);
+                if (string.IsNullOrEmpty(typeNamespace))
+                {
+                    // Either the typeName is not the full type name or this type is at the top level.
+                    return true;
+                }
+
+                // Remove global:: prefix from namespace.
+                const string globalPrefix = "global::";
+                var normalizedNamespace = @namespace.AsSpan();
+                if (@namespace.StartsWith(globalPrefix, StringComparison.Ordinal))
+                {
+                    normalizedNamespace = normalizedNamespace[globalPrefix.Length..];
+                }
+
+                return normalizedNamespace.Equals(typeNamespace.AsSpan(), StringComparison.Ordinal);
             }
         }
 

src/Compiler/Microsoft.AspNetCore.Razor.Language/test/DefaultRazorTagHelperBinderPhaseTest.cs

@@ -1296,6 +1296,35 @@ @using SomeProject.SomeOtherFolder
         Assert.Equal(2, visitor.Matches.Count);
     }
 
+    [Fact]
+    public void ComponentDirectiveVisitor_MatchesIfNamespaceInUsing_GlobalPrefix()
+    {
+        // Arrange
+        var currentNamespace = "SomeProject";
+        var componentDescriptor = CreateComponentDescriptor(
+            "Counter",
+            "SomeProject.SomeOtherFolder.Counter",
+            AssemblyA);
+        var descriptors = new[]
+        {
+            componentDescriptor,
+        };
+        var filePath = "C:\\SomeFolder\\SomeProject\\Counter.cshtml";
+        var content = """
+            @using global::SomeProject.SomeOtherFolder
+            """;
+        var sourceDocument = CreateComponentTestSourceDocument(content, filePath);
+        var tree = RazorSyntaxTree.Parse(sourceDocument);
+        var visitor = new DefaultRazorTagHelperContextDiscoveryPhase.ComponentDirectiveVisitor(sourceDocument.FilePath, descriptors, currentNamespace);
+
+        // Act
+        visitor.Visit(tree);
+
+        // Assert
+        var match = Assert.Single(visitor.Matches);
+        Assert.Same(componentDescriptor, match);
+    }
+
     [Fact]
     public void ComponentDirectiveVisitor_DoesNotMatchForUsingAliasAndStaticUsings()
     {
@@ -1335,8 +1364,10 @@ @using static SomeProject.SomeOtherFolder.Foo
     [InlineData("", "", true)]
     [InlineData("Foo", "Project", true)]
     [InlineData("Project.Foo", "Project", true)]
+    [InlineData("Project.Foo", "global::Project", true)]
     [InlineData("Project.Bar.Foo", "Project.Bar", true)]
     [InlineData("Project.Foo", "Project.Bar", false)]
+    [InlineData("Project.Foo", "global::Project.Bar", false)]
     [InlineData("Project.Bar.Foo", "Project", false)]
     [InlineData("Bar.Foo", "Project", false)]
     public void IsTypeInNamespace_WorksAsExpected(string typeName, string @namespace, bool expected)

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

@@ -8504,6 +8504,34 @@ @layout MainLayout
         CompileToAssembly(generated, throwOnFailure: false);
     }
 
+    [Fact]
+    public void ComponentImports_GlobalPrefix()
+    {
+        // Arrange
+        AdditionalSyntaxTrees.Add(Parse("""
+            using Microsoft.AspNetCore.Components;
+
+            namespace MyComponents
+            {
+                public class Counter : ComponentBase
+                {
+                }
+            }
+            """));
+
+        // Act
+        var generated = CompileToCSharp("Index.razor", """
+            @using global::MyComponents
+
+            <Counter />
+            """);
+
+        // Assert
+        CompileToAssembly(generated);
+        Assert.DoesNotContain("<Counter", generated.Code);
+        Assert.Contains("global::MyComponents.Counter", generated.Code);
+    }
+
     [Fact]
     public void Component_NamespaceDirective_InImports()
     {