I much prefer being warned about unused variables and explicitely having to silence those warnings on a case by case basis though - especially when refactoring (one option is to use a wrapper macro MAYBE_UNUSED(bla) macro, or GCC's __attribute__((unused)) or the C++ [[unused]], or the C23 [[maybe_unused]].

But of all those options, "(void)bla;" might actually be the least clutter (and at the same time the most compatible).