ILSpy "Failed to resolve assembly" in AstBuilder

Question

I want to decompile a method in my assembly, which references e.g. 'Microsoft.SharePoint.dll', but I have no SharePoint installed on the machine. If I use the following code I get an Mono.Cecil.AssemblyResolutionException 'failed to resolve assembly Microsoft.SharePoint...'.

AssemblyDefinition assembly = AssemblyDefinition.ReadAssembly("PathToMyAssembly");
ICSharpCode.Decompiler.DecompilerContext context = new ICSharpCode.Decompiler.DecompilerContext(assembly.MainModule);
AstBuilder decompiler = new AstBuilder(context);
decompiler.AddMethod(method); <!-- here it crashes -->

With the ILSpy GUI I can load my assembly without errors (on the same machine without SharePoint).

What do I need to change in my code?

Answer 1

I found the solution myself. I created my own AssemblyResolver which catches the AssemblyResolutionException and returns null for missing referenced assemblies.

public class MyDefaultAssemblyResolver : DefaultAssemblyResolver
{
    public override AssemblyDefinition Resolve(AssemblyNameReference name)
    {
        try
        {
            return base.Resolve(name);
        }
        catch { }
        return null;            
    }

    public override AssemblyDefinition Resolve(AssemblyNameReference name, ReaderParameters parameters)
    {
        try
        {
            return base.Resolve(name, parameters);
        }
        catch { }
        return null;
    }

    public override AssemblyDefinition Resolve(string fullName)
    {   
        try
        {
            return base.Resolve(fullName);
        }
        catch { }
        return null;
    }

    public override AssemblyDefinition Resolve(string fullName, ReaderParameters parameters)
    {
        try
        {
            return base.Resolve(fullName, parameters);
        }
        catch { }
        return null;
    }
}

Then I use it

var resolver = new MyDefaultAssemblyResolver();
resolver.AddSearchDirectory("FolderOfMyAssembly");
var parameters = new ReaderParameters
{
    AssemblyResolver = resolver,
};

AssemblyDefinition assembly = AssemblyDefinition.ReadAssembly("PathToMyAssembly", parameters);

I found the solution by debugging the ILSpy GUI (source code is fortunately available).