Only support adding names from local functions

Author: captainsafia

src/Http/Routing/src/Builder/MinimalActionEndpointRouteBuilderExtensions.cs

@@ -185,10 +185,14 @@ public static MinimalActionEndpointConventionBuilder Map(
             // Add MethodInfo as metadata to assist with OpenAPI generation for the endpoint.
             builder.Metadata.Add(action.Method);
 
-            // Methods defined in a top-level program are generated as statics so the delegate
-            // target will be null. Inline lambdas are compiler generated properties so they can
-            // be filtered that way.
-            if (action.Target == null || !TypeHelper.IsCompilerGenerated(action.Method.Name))
+            // We only add endpoint names for types that are not compiler generated since
+            // compiler generated types are mangled by default. This logic can be changed once
+            // https://github.com/dotnet/roslyn/issues/55651 is addressed. For now, this will
+            // not set the endpoint name metadata for:
+            // - Local functions
+            // - Inline lambdas
+            // - Static functions
+            if (!TypeHelper.IsCompilerGenerated(action.Method.Name))
             {
                 builder.Metadata.Add(new EndpointNameMetadata(action.Method.Name));
             }

src/Http/Routing/test/UnitTests/Builder/MinimalActionEndpointRouteBuilderExtensionsTest.cs

@@ -361,8 +361,9 @@ public void MapFallbackWithoutPath_BuildsEndpointWithLowestRouteOrder()
 
         [Fact]
         // This test scenario simulates methods defined in a top-level program
-        // which are compiler generated.
-        public void MapMethod_SetsEndpointNameForInnerMethod()
+        // which are compiler generated. This can be re-examined once
+        // https://github.com/dotnet/roslyn/issues/55651 is addressed.
+        public void MapMethod_DoesNotEndpointNameForInnerMethod()
         {
             var builder = new DefaultEndpointRouteBuilder(new ApplicationBuilder(new EmptyServiceProvdier()));
             string InnerGetString() => "TestString";
@@ -373,8 +374,7 @@ public void MapMethod_SetsEndpointNameForInnerMethod()
             var endpoint = Assert.Single(dataSource.Endpoints);
 
             var endpointName = endpoint.Metadata.GetMetadata<IEndpointNameMetadata>();
-            Assert.NotNull(endpointName);
-            Assert.Equal("InnerGetString", endpointName?.EndpointName);
+            Assert.Null(endpointName);
         }
 
         [Fact]