message: in resolution of [Wsign-compare] warning id 10
  LargeAllocationWarningBytes() is implied to be a quantity ( it calls AvailableRam(), which unless improperly named, is a quantity/ i.e. non-negative ).
  Given LargeAllocationWarningBytes() is a quantity, it can be cast to size_t with behavior constrained to be as-intend.
diff: @@ -75,7 +75,7 @@ class CPUAllocator : public Allocator {
  string Name() override { return "cpu"; }
  void* AllocateRaw(size_t alignment, size_t num_bytes) override {
  - if (num_bytes > LargeAllocationWarningBytes() &&
  + if (num_bytes > static_cast<size_t>(LargeAllocationWarningBytes()) &&
  single_allocation_warning_count_ < kMaxSingleAllocationWarnings) {
  ++single_allocation_warning_count_;
  LOG(WARNING) << "Allocation of " << num_bytes << " exceeds "
  