I've just created another release of my bleeding-edge-toolchain script, which builds a complete toolchain for ARM microcontrollers. This toolchain uses the most recent versions of all possible components:
EDIT: Stable GCC 7.1.0 is already released - see first reply below for details!
If you're very impatient waiting for the full GCC 7.1.0 release (expected this month), you can try experimental GCC 7 version with your ARM microcontroller right now (…