I'm getting the following error when trying to compile:

Code
src/mess/machine/snescart.c: In member function 'int snes_state::device_image_load_snes_cart(device_image_interface&)':
src/mess/machine/snescart.c:647:24: error: variable 'st_bios' set but not used [-Werror=unused-but-set-variable]
cc1plus.exe: all warnings being treated as errors
make: *** [obj/windows64/mess/machine/snescart.o] Error 1

Windows 7 64-bit [SVN 21700]