message: fixed compiler warnings in nlogmann::json
diff: @@ -11410,6 +11410,14 @@ class serializer
  }
  }
  + template<typename NumberType, detail::enable_if_t<
  + std::is_same<NumberType, number_unsigned_t>::value, int> = 0>
  + bool is_negative_integer(NumberType x) { return false; }
  +
  + template<typename NumberType, detail::enable_if_t<
  + std::is_same<NumberType, number_integer_t>::value, int> = 0>
  + bool is_negative_integer(NumberType x) { return x<0; }
  +
  /*!
  @brief dump an integer
  @@ -11432,7 +11440,7 @@ class serializer
  return;
  }
  - const bool is_negative = std::is_same<NumberType, number_integer_t>::value and not (x >= 0); // see issue #755
  + const bool is_negative = is_negative_integer(x); // see issue #755
  std::size_t i = 0;
  while (x != 0)
  