razor: Razor compiler doesn't understand "@using Alias = Namespace.ComponentClass"

Using a Razor component via an alias isn’t recognized by the compiler

If I want to rename/alias a Razor component when using it in a Razor page/Razor component, I should be able to reference it using the alias syntax, @using Alias = Namespace.ComponentClass. However, the Razor compiler does not recognized <Alias /> as a component, and will instead generate code that treats <Alias /> as a MarkupString.

Visual Studio Razor editor doesn’t recognize Alias as a ComponentClass component either.

To Reproduce

Steps to reproduce the behavior:

1. Setup test project:

dotnet new blazor -o using-rename
cd .\using-rename\
mkdir Components
cd .\Components\
dotnet new razorcomponent -n Test

1. Modify .\using-rename\Pages\Index.razor to look like this:

@page "/"
@using Renamed = using_rename.Components.Test
<Renamed />

1. Build using dotnet build. See no errors in output.

2. See .\using-rename\obj\Debug\netstandard2.0\Razor\Pages\Index.razor.g.cs contains builder.AddMarkupContent(3, "\r\n\r\n<Renamed></Renamed>");. Here is the relevant snippet:

using Renamed = using_rename.Components.Test;

[Microsoft.AspNetCore.Components.Layouts.LayoutAttribute(typeof(MainLayout))]
[Microsoft.AspNetCore.Components.RouteAttribute("/")]
public class Index : Microsoft.AspNetCore.Components.ComponentBase
{
	protected override void BuildRenderTree(Microsoft.AspNetCore.Components.RenderTree.RenderTreeBuilder builder)
	{
		builder.AddMarkupContent(0, "<h1>Hello, world!</h1>\r\n\r\nWelcome to your new app.\r\n\r\n");
		builder.OpenComponent<using_rename.Shared.SurveyPrompt>(1);
		builder.AddAttribute(2, "Title", "How is Blazor working for you?");
		builder.CloseComponent();
		builder.AddMarkupContent(3, "\r\n\r\n<Renamed></Renamed>"); 
	}
}

Expected behavior

Visual Studio should recognize Renamed as a using_rename.Components.Test component, and the compiler should output the correct C# render tree builder code.

Additional context

.NET Core SDK (reflecting any global.json):
 Version:   3.0.100-preview7-012821
 Commit:    6348f1068a

Runtime Environment:
 OS Name:     Windows
 OS Version:  10.0.16299
 OS Platform: Windows
 RID:         win10-x64
 Base Path:   C:\Program Files\dotnet\sdk\3.0.100-preview7-012821\

Host (useful for support):
  Version: 3.0.0-preview7-27912-14
  Commit:  4da6ee6450

.NET Core SDKs installed:
  2.1.201 [C:\Program Files\dotnet\sdk]
  2.1.202 [C:\Program Files\dotnet\sdk]
  2.1.400 [C:\Program Files\dotnet\sdk]
  2.1.402 [C:\Program Files\dotnet\sdk]
  2.1.403 [C:\Program Files\dotnet\sdk]
  2.1.500 [C:\Program Files\dotnet\sdk]
  2.1.504 [C:\Program Files\dotnet\sdk]
  2.1.600-preview-009497 [C:\Program Files\dotnet\sdk]
  2.1.600 [C:\Program Files\dotnet\sdk]
  2.1.601 [C:\Program Files\dotnet\sdk]
  2.1.602 [C:\Program Files\dotnet\sdk]
  2.1.700-preview-009618 [C:\Program Files\dotnet\sdk]
  2.1.700 [C:\Program Files\dotnet\sdk]
  2.1.800-preview-009677 [C:\Program Files\dotnet\sdk]
  2.1.800-preview-009696 [C:\Program Files\dotnet\sdk]
  3.0.100-preview7-012821 [C:\Program Files\dotnet\sdk]

.NET Core runtimes installed:
  Microsoft.AspNetCore.All 2.1.2 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.4 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.5 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.6 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.7 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.8 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.9 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.11 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.12 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.App 2.1.2 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.4 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.5 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.6 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.7 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.8 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.9 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.11 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.12 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 3.0.0-preview3-19153-02 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 3.0.0-preview7.19365.7 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 2.0.7 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.0.9 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.2 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.4 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.5 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.6 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.7 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.8 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.9 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.11 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.12 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 3.0.0-preview7-27912-14 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.WindowsDesktop.App 3.0.0-preview7-27912-14 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]