rust-lang/rust — pull request #19534 by scialex (2014-12-04 20:12:55+00:00)
Title: Add ability to use custom alloc::heap::imp

Adds the ability to use a custom allocator heap by passing either --cfg
external_crate and --extern external= or --cfg
external_funcs and defining the allocator functions prefixed by 'rust_'
somewhere.

This is useful for many applications including OS/embedded development,
and allocator development and testing.