Link multiple .netmodule files

This past week I was attempting to add evidence to an assembly directly, i.e. to bake it into the DLL, to satisfy some security requirements. The .Net linker (al.exe) has an option (/evidence:) that lets you add a serialized Evidence object as a resource with the magic name Security.Evidence. There is some discussion of producing this resource file here.

A little poking around on the web showed me how to compile to .netmodule files, which seemed analogous to .obj files in the C++ Win32 world. I had to rework the .csproj file produced by Visual Studio so that I could invoke msbuild and produce one .netmodule file for each .cs file, build the resources etc and then link.

Everything appeared to work just fine. The link stage didn't give any errors or warnings. Curiously, the resulting DLL was only about 8Kb in size. The assembly when produced in Visual Studio from the .csproj file is a little more than 1Mb.

This turns out to be "by design". You can indeed compile to a .netmodule and link but if you have more than one .netmodule file it really is not analogous to the linking of various C++ obj files to produce a single DLL. Instead, the resulting assembly is a meta-assembly. It contains references to the various .netmodule files, which you would have to deploy with the assembly.

Luckily all was saved when I realized that I could compile all the files and produce a single assembly directly using csc.exe (the command line C# compiler). I just needed to specify a resource file containing the serialized Evidence and name the resource Security.Evidence. Indeed, it would seem there is little that you can do with the linker (al.exe) that you couldn't just do with csc.exe (the command line compiler), a point made here.