Merging(ILMerge) assemblies targeting the .Net Runtime v4.0

Today I started the process of upgrading a lot of projects to Visual Studio 2010 and at the same time I set the target framework to 4.0.

Everything went relatively smooth except for the some projects where we have modified the msbuild file to include a call to ILMerge.

First it complained it could not resolve the reference to System.Core

Unresolved assembly reference not allowed: System.Core.

As it turned out I needed to tell ILMerge what framework version to use and where it is located.

Mike Barnet has mentioned this at Microsoft Research and the solution is to add a command line parameter like this: /targetplatform:v4,<path to your v4 framework directory> 

So where is the v4 framework directory?

It is located in “C:\Windows\Microsoft.NET\Framework\v4.0.30319” provided you have a default installation.

So I added the command line parameter like this

/targetplatform:v4“C:\Windows\Microsoft.NET\Framework\v4.0.30319”

Make sure that you don’t have a space between the version and the path. It actually caused a stack overflow on my machine :)

Anyway this worked very well and no more complaints about unresolved assemblies.

That was until I tried to merge an assembly that referenced the PresentationCore.dll.

Unresolved assembly reference..again.

What now?

After some investigation I found out that PresentationCore.dll is not located in “C:\Windows\Microsoft.NET\Framework\v4.0.30319”, but in a WPF subfolder.

Aha, that must be it.

The trick here is that the path to the framework should be this
“C:\Program Files\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.0”

This directory contains all the framework assemblies including PresentationCore.dll

So I changed the command line parameter to

/targetplatform:v4“C:\Program Files\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.0”

Suddenly all merging of assemblies succeeded.