Towards Scala/.net 2.0

A propos of my last bit of banging head against a wall... Oh, and these snippets are definitely offered under the WTFPL.

The main things that the scala-msil compilation balks at when looking at .Net assemblies post framework 1.x are generics; and things marked as var. Looking at the source in http://lampsvn.epfl.ch/svn-repos/scala/msil/trunk/src/, the first changes to make are, first in msil/util/Signature.java, add the extra byte code values

    public static final int ELEMENT_TYPE_VAR = 0x13;     // a class type variable VAR
    /***/
    public static final int  ELEMENT_TYPE_GENERICINST    = 0x15;     // GENERICINST    ...

and then start to do something about parsing them in msil/PEFile.java, in method PEFile.Sig.decodeType0()

        case ELEMENT_TYPE_GENERICINST:
        // Followed by <type> token
        //ELEMENT_TYPE_GENERICINST <an mdTypeDef metadata token> <argument Count> <arg1> ... <argN>
        {
            // base type
            int tmp = readByte();
            if((tmp != ELEMENT_TYPE_VALUETYPE) && (tmp != ELEMENT_TYPE_CLASS))
                throw new RuntimeException("*1*>> "+ byte2hex(tmp) +
        "@" + pos() + " in " + this);   
            int id = decodeInt();
            type = pemodule.getTypeDefOrRef(id);
            if (type == null)   throw new RuntimeException("**>> "+ byte2hex(desc) +
        "@" + pos() + " in " + this);
            // number of type arguments
            int num = decodeInt();
            System.out.println("num = "+num);
            for(int i=0;i<num;++i)
            {
                Type t = decodeType0();
                //TODO: use this information
            }
        }
        break;

        case ELEMENT_TYPE_VAR:
        {
            int index = decodeInt();
            System.out.println("var of type "+index);
            // TODO: actually look up what the index means 
            return Type.GetType("System.Object");
        }

This is necessary but not sufficient -- this still leaves problems with types involving templated subtypes or interfaces, for which the first TODO is probably meaningful. As a consequence we're still a long way from a "hello .net 2.0 world!" example yet; let alone a rebuilt scala-compiler.jar, alas.