message: use extended constexpr functions only from C++14 onwards
diff: @@ -149,44 +149,68 @@ class Value {
  constexpr bool isString() const noexcept { return _valueType == ValueType::String; }
  constexpr bool getBool() const noexcept {
  +#if __cplusplus >= 201300
  + // extended constexpr functions are only available from C++14 onwards
  VELOCYPACK_ASSERT(_cType == CType::Bool);
  +#endif
  return _value.b;
  }
  constexpr double getDouble() const noexcept {
  +#if __cplusplus >= 201300
  + // extended constexpr functions are only available from C++14 onwards
  VELOCYPACK_ASSERT(_cType == CType::Double);
  +#endif
  return _value.d;
  }
  constexpr int64_t getInt64() const noexcept {
  +#if __cplusplus >= 201300
  + // extended constexpr functions are only available from C++14 onwards
  VELOCYPACK_ASSERT(_cType == CType::Int64);
  +#endif
  return _value.i;
  }
  constexpr uint64_t getUInt64() const noexcept {
  +#if __cplusplus >= 201300
  + // extended constexpr functions are only available from C++14 onwards
  VELOCYPACK_ASSERT(_cType == CType::UInt64);
  +#endif
  return _value.u;
  }
  constexpr std::string const* getString() const noexcept {
  +#if __cplusplus >= 201300
  + // extended constexpr functions are only available from C++14 onwards
  VELOCYPACK_ASSERT(_cType == CType::String);
  +#endif
  return _value.s;
  }
  #ifdef VELOCYPACK_HAS_STRING_VIEW
  constexpr std::string_view const* getStringView() const noexcept {
  +#if __cplusplus >= 201300
  + // extended constexpr functions are only available from C++14 onwards
  VELOCYPACK_ASSERT(_cType == CType::StringView);
  +#endif
  return _value.sv;
  }
  #endif
  constexpr void const* getExternal() const noexcept {
  +#if __cplusplus >= 201300
  + // extended constexpr functions are only available from C++14 onwards
  VELOCYPACK_ASSERT(_cType == CType::VoidPtr);
  +#endif
  return _value.e;
  }
  constexpr char const* getCharPtr() const noexcept {
  +#if __cplusplus >= 201300
  + // extended constexpr functions are only available from C++14 onwards
  VELOCYPACK_ASSERT(_cType == CType::CharPtr);
  +#endif
  return _value.c;
  }
  };
  