Referencing an aligned empty struct in C?

I came across an odd set of macros in the SameBoy emulator (v0.13) that seems to use an empty struct to address data. It looks like this:

#define GB_PADDING(type, old_usage) type old_usage##__do_not_use#define GB_SECTION(name, ...)     \        __attribute__ ((aligned (8))) struct {} name##_section_start;  \        __VA_ARGS__;   \        struct {} name##_section_end#define GB_SECTION_OFFSET(name)   \        (offsetof(GB_gameboy_t, name##_section_start))#define GB_SECTION_SIZE(name)     \         (offsetof(GB_gameboy_t, name##_section_end) - offsetof(GB_gameboy_t, name##_section_start))#define GB_GET_SECTION(gb, name)  \        ((void*)&((gb)->name##_section_start))

It seems GB_gameboy_t is a type of some kind (probably for the GameBoy internal structure). However the part that is bothering me is the GB_SECTION and GB_GET_SECTION macros. It is clear that the purpose of these macros is to align data. However, I am lost on what an empty struct (labeled name##_section_start) expands to. Does it expand to nothing (i.e. 0 bytes)? If so, then GB_GET_SECTION would point to whatever __VA_ARGS__ is. But then what would be the point of the __attribute__ ((aligned (8))) qualifier? Or does the empty struct expand to some garbage padding bytes? If it does, then GB_GET_SECTION would point to garbage data.

So which one is it?