mozilla/rust — pull request #6336 by nikomatsakis (2013-05-08 18:47:49+00:00)
Title: Refactor representation of bounds to separate out BuiltinBounds into its own type. 

Use a bitset to represent built-in bounds. There are several places in the language where only builtin bounds (aka kinds) will be accepted, e.g. on closures, destructor type parameters perhaps, and on trait types.

r? @brson