Regarding type argument syntax

Hello all, This concerns the RFC on generics. It isn't an extension to the proposal, a sale or anything, just hypothetical, it only regards a technicality about its implementation of syntax. The issue is the T_SR >> for nested type arguments. I understand the reason this is difficult, and I know resolving it may involve hacking the lexer. So all I want to know is **IF** the RFC was accepted, what action would be acceptable to internals to make it work? Thanks, Dominic