From 33af1c84fb2c98cb79b80fb0baca1f0d9d3b373a Mon Sep 17 00:00:00 2001
From: Aaron Robinson <arobins@microsoft.com>
Date: Thu, 25 Jul 2024 21:46:20 -0700
Subject: [PATCH] Add note about registering TLB (#41907)

* Add note about registering TLB

---------

Co-authored-by: Genevieve Warren <24882762+gewarren@users.noreply.github.com>
---
 docs/core/native-interop/expose-components-to-com.md | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/docs/core/native-interop/expose-components-to-com.md b/docs/core/native-interop/expose-components-to-com.md
index d458c48fd06d5..a711fa4e80edf 100644
--- a/docs/core/native-interop/expose-components-to-com.md
+++ b/docs/core/native-interop/expose-components-to-com.md
@@ -73,6 +73,8 @@ The resulting output will have a `ProjectName.dll`, `ProjectName.deps.json`, `Pr
 
 Open an elevated command prompt and run `regsvr32 ProjectName.comhost.dll`. That will register all of your exposed .NET objects with COM.
 
+If you intend to [embed a type library (TLB)](#embed_tlb), it's recommended to also define functions using [`ComRegisterFunctionAttribute`](/dotnet/api/system.runtime.interopservices.comregisterfunctionattribute) and [`ComUnregisterFunctionAttribute`](/dotnet/api/system.runtime.interopservices.comunregisterfunctionattribute). These functions can be used to register and unregister the TLB for the COM server. For a complete example, see the [`OutOfProcCOM`](https://github.com/dotnet/samples/tree/main/core/extensions/OutOfProcCOM) sample.
+
 ## Enabling RegFree COM
 
 1. Open the `.csproj` project file and add `<EnableRegFreeCom>true</EnableRegFreeCom>` inside a `<PropertyGroup></PropertyGroup>` tag.
@@ -80,7 +82,7 @@ Open an elevated command prompt and run `regsvr32 ProjectName.comhost.dll`. That
 
 The resulting output will now also have a `ProjectName.X.manifest` file. This file is the side-by-side manifest for use with Registry-Free COM.
 
-## Embedding type libraries in the COM host
+## <a name="embed_tlb"></a> Embedding type libraries in the COM host
 
 Unlike in .NET Framework, there is no support in .NET Core or .NET 5+ for generating a [COM Type Library (TLB)](/windows/win32/midl/com-dcom-and-type-libraries#type-library) from a .NET assembly. The guidance is to either manually write an IDL file or a C/C++ header for the native declarations of the COM interfaces. If you decide to write an IDL file, you can compile it with the Visual C++ SDK's MIDL compiler to produce a TLB.