sql/item_sum.cc:
  "unused variable" warning
sql/item_timefunc.cc:
  "unused variable" warning
sql/log_event.h:
  const bool is_valid() -> bool is_valid() const
sql/opt_range.cc:
  cast log's argument to double (otherwise an error on some compilers)
sql/opt_range.h:
  get_quick_select_for_ref should be declared in the global scope to be visible.