What is the use of BX_UNUSED(_thread) and when to use it ?

[meiry]

i can see in the entry_sdl.cpp there is use of BX_UNUSED(_thread); what is the use of it , and why do i need it ? trying to look at the code in https://github.com/bkaradzic/bx/blob/master/include/bx/macros.h and i find it very confusing ,

int32_t MainThreadEntry::threadFunc(bx::Thread* _thread, void* _userData)
	{
		BX_UNUSED(_thread);

		MainThreadEntry* self = (MainThreadEntry*)_userData;
		int32_t result = main(self->m_argc, self->m_argv);

		SDL_Event event;
		SDL_QuitEvent& qev = event.quit;
		qev.type = SDL_QUIT;
		SDL_PushEvent(&event);
		return result;
	}