[Mono-devel-list] CustomAttributeBuilder and custom marshalers

[Marcus]

I'm working on a possible patch for the bug I reported:
http://bugs.ximian.com/show_bug.cgi?id=62610

Essentially, Mono does not have code to permit attaching a custom marshaler 
using the CustomAttributeBuilder class. This can be achieved with a vary 
small patch, but I do have a question about UnmanagedMarshal.DefineCustom(). 
The method takes both "Type typeref" and "string mtype", which appear to 
correspond to the MarshalAsAttributes MarshalTypeRef and MarshalType, 
respectively. Is it necessary to supply both values for both, or is the Mono 
engine smart enough to use whichever is non-null?