mozilla/rust — pull request #7363 by bblum (2013-06-25 00:05:20+00:00)
Title: Stack closure soundness.

The fourth commit here is meant to be a temporary hold-over. Whether or not there is added a way for the compiler to "implicitly borrow" stack closures in this way, there should be a codegen optimization that prevents having to traverse possibly-very-many function pointers to find the function you ultimately wanted to call.