const unknown = "unknown type"
	if w == nil {
		return unknown
	}
	switch {
	case w.ArrayT != nil:
		return w.ArrayT.Name
	case w.SliceT != nil:
		return w.SliceT.Name
	case w.StructT != nil:
		return w.StructT.Name
	case w.MapT != nil:
		return w.MapT.Name
	case w.GobEncoderT != nil:
		return w.GobEncoderT.Name
	case w.BinaryMarshalerT != nil:
		return w.BinaryMarshalerT.Name

	// Slices
	{name: "SliceMake", argLength: 3},                // arg0=ptr, arg1=len, arg2=cap
	{name: "SlicePtr", argLength: 1, typ: "BytePtr"}, // ptr(arg0)
	{name: "SliceLen", argLength: 1},                 // len(arg0)
	{name: "SliceCap", argLength: 1},                 // cap(arg0)
	// SlicePtrUnchecked, like SlicePtr, extracts the pointer from a slice.