message: Cast to right type for reserved_ subtraction
  reserved_ is a size_t so ensure that the output of cur_ - buf_ is cast to that to avoid compiler warnings.
diff: @@ -933,7 +933,7 @@ class vector_downward {
  Allocator *get_custom_allocator() { return allocator_; }
  uoffset_t size() const {
  - return static_cast<uoffset_t>(reserved_ - (cur_ - buf_));
  + return static_cast<uoffset_t>(reserved_ - static_cast<size_t>(cur_ - buf_));
  }
  uoffset_t scratch_size() const {
  