I'm planning on making an OS with Rust. The source code can be found here. There's nothing there yet!
In this step I compiled gcc 6.1.0 on OS X with the target as x86_64-elf and a suffix so I can have one cross compiler for the kernel and one for user-space. Doing this allows me to build for the target on my machine before the OS can be used for development.
On my first attempt I installed GCC and Binutils without a target. After reading the Why do I need a Cross Compiler? page I decided to build again with a target this time to avoid problems.
To install gcc I followed the steps with some variations from the very useful osdev cross compiler page found here. I built the dependencies (GMP, MPFR, MPC, ISL) separately instead, each with the same prefix path. Now that I have a cross compiler, the next step is to make the kernel.