From f2f0bed885334740da04ffb4906583329f0a5a1a Mon Sep 17 00:00:00 2001
From: Ajay Bhargav Baaskaran <ajaybhargavb@gmail.com>
Date: Tue, 16 Jul 2019 13:11:15 -0700
Subject: [PATCH] Support [Parameter] attribute on base class of overridden
 properties (dotnet/aspnetcore-tooling#835)

* Support [Parameter] attribute on base class of overridden properties

* Fix test
\n\nCommit migrated from https://github.com/dotnet/aspnetcore-tooling/commit/c228339bb38de8508e391a7c14577f0d5ae43c9c
---
 .../ComponentTagHelperDescriptorProvider.cs   |  7 ++
 ...omponentTagHelperDescriptorProviderTest.cs | 67 +++++++++++++++++++
 2 files changed, 74 insertions(+)

diff --git a/src/Razor/Microsoft.CodeAnalysis.Razor/src/ComponentTagHelperDescriptorProvider.cs b/src/Razor/Microsoft.CodeAnalysis.Razor/src/ComponentTagHelperDescriptorProvider.cs
index 17eb8b3918..30b8983983 100644
--- a/src/Razor/Microsoft.CodeAnalysis.Razor/src/ComponentTagHelperDescriptorProvider.cs
+++ b/src/Razor/Microsoft.CodeAnalysis.Razor/src/ComponentTagHelperDescriptorProvider.cs
@@ -386,6 +386,13 @@ namespace Microsoft.CodeAnalysis.Razor
 
                     if (!property.GetAttributes().Any(a => a.AttributeClass == symbols.ParameterAttribute))
                     {
+                        if (property.IsOverride)
+                        {
+                            // This property does not contain [Parameter] attribute but it was overridden. Don't ignore it for now.
+                            // We can ignore it if the base class does not contains a [Parameter] as well.
+                            continue;
+                        }
+
                         // Does not have [Parameter]
                         kind = PropertyKind.Ignored;
                     }
diff --git a/src/Razor/Microsoft.CodeAnalysis.Razor/test/ComponentTagHelperDescriptorProviderTest.cs b/src/Razor/Microsoft.CodeAnalysis.Razor/test/ComponentTagHelperDescriptorProviderTest.cs
index 84e92ba30f..329a8606b5 100644
--- a/src/Razor/Microsoft.CodeAnalysis.Razor/test/ComponentTagHelperDescriptorProviderTest.cs
+++ b/src/Razor/Microsoft.CodeAnalysis.Razor/test/ComponentTagHelperDescriptorProviderTest.cs
@@ -1436,5 +1436,72 @@ namespace Test
 
             Assert.Empty(component.BoundAttributes);
         }
+
+        [Fact] // Testing multilevel overrides with the [Parameter] attribute on different levels.
+        public void Execute_MultiLevelOverriddenProperties_CreatesDescriptorCorrectly()
+        {
+            // Arrange
+
+            var compilation = BaseCompilation.AddSyntaxTrees(Parse(@"
+using Microsoft.AspNetCore.Components;
+
+namespace Test
+{
+    public abstract class MyBaseComponent : ComponentBase
+    {
+        [Parameter]
+        public virtual string Header { get; set; }
+
+        public virtual string Footer { get; set; }
+    }
+
+    public abstract class MyDerivedComponent1 : MyBaseComponent
+    {
+        public override string Header { get; set; }
+
+        [Parameter]
+        public override string Footer { get; set; }
+    }
+
+    public class MyDerivedComponent2 : MyDerivedComponent1
+    {
+        public override string Header { get; set; }
+
+        public override string Footer { get; set; }
+    }
+}
+"));
+
+            Assert.Empty(compilation.GetDiagnostics());
+
+            var context = TagHelperDescriptorProviderContext.Create();
+            context.SetCompilation(compilation);
+
+            var provider = new ComponentTagHelperDescriptorProvider();
+
+            // Act
+            provider.Execute(context);
+
+            // Assert
+            var components = ExcludeBuiltInComponents(context);
+            components = AssertAndExcludeFullyQualifiedNameMatchComponents(components, expectedCount: 1);
+            var component = Assert.Single(components, c => c.IsComponentTagHelper());
+
+            Assert.Equal("TestAssembly", component.AssemblyName);
+            Assert.Equal("Test.MyDerivedComponent2", component.Name);
+
+            Assert.Collection(
+                component.BoundAttributes.OrderBy(a => a.Name),
+                a =>
+                {
+                    Assert.Equal("Footer", a.Name);
+                    Assert.Equal("System.String", a.TypeName);
+                },
+                a =>
+                {
+                    Assert.Equal("Header", a.Name);
+                    Assert.Equal("System.String", a.TypeName);
+                });
+        }
     }
 }