问题描述
我正在尝试使用 Boost.serialize
。它似乎工作正常,但是当我使用 -Wextra
(版本 10.2.0)打开 -Wall
和 g++
警告时收到警告。
当我关闭警告时,它运行良好,并且编译良好。但是,我希望能够正确地摆脱它们。我已经尝试了几个小时,但找不到解决方案。我发现了一些类似警告的例子,但这些都是没有定义默认构造函数的情况。
我在下面创建了一个最小示例:
#include <boost/archive/text_oarchive.hpp>
#include <boost/archive/text_iarchive.hpp>
struct minimal {
minimal()=default;
minimal(int in)
: x {in}
{}
template <typename Archive>
void serialize(Archive & ar,const unsigned vers){
ar & x;
}
int x;
};
int main()
{
std::stringstream ss;
boost::archive::text_oarchive oa {ss};
minimal M {10} ;
oa << M;
return 0;
}
我编译时的输出是
g++ -Wextra -Wall minimal.cc -lboost_serialization
minimal.cc: In instantiation of 'void minimal::serialize(Archive&,unsigned int) [with Archive = boost::archive::text_oarchive]':
/usr/include/boost/serialization/access.hpp:116:20: required from 'static void boost::serialization::access::serialize(Archive&,T&,unsigned int) [with Archive = boost::archive::text_oarchive; T = minimal]'
/usr/include/boost/serialization/serialization.hpp:59:22: required from 'void boost::serialization::serialize(Archive&,unsigned int) [with Archive = boost::archive::text_oarchive; T = minimal]'
/usr/include/boost/serialization/serialization.hpp:109:14: required from 'void boost::serialization::serialize_adl(Archive&,unsigned int) [with Archive = boost::archive::text_oarchive; T = minimal]'
/usr/include/boost/archive/detail/oserializer.hpp:153:40: required from 'void boost::archive::detail::oserializer<Archive,T>::save_object_data(boost::archive::detail::basic_oarchive&,const void*) const [with Archive = boost::archive::text_oarchive; T = minimal]'
/usr/include/boost/archive/detail/oserializer.hpp:106:1: [ skipping 2 instantiation contexts,use -ftemplate-backtrace-limit=0 to disable ]
/usr/include/boost/archive/detail/oserializer.hpp:315:22: required from 'static void boost::archive::detail::save_non_pointer_type<Archive>::invoke(Archive&,const T&) [with T = minimal; Archive = boost::archive::text_oarchive]'
/usr/include/boost/archive/detail/oserializer.hpp:539:18: required from 'void boost::archive::save(Archive&,T&) [with Archive = boost::archive::text_oarchive; T = const minimal]'
/usr/include/boost/archive/detail/common_oarchive.hpp:71:22: required from 'void boost::archive::detail::common_oarchive<Archive>::save_override(T&) [with T = const minimal; Archive = boost::archive::text_oarchive]'
/usr/include/boost/archive/basic_text_oarchive.hpp:83:52: required from 'void boost::archive::basic_text_oarchive<Archive>::save_override(T&) [with T = const minimal; Archive = boost::archive::text_oarchive]'
/usr/include/boost/archive/detail/interface_oarchive.hpp:70:36: required from 'Archive& boost::archive::detail::interface_oarchive<Archive>::operator<<(const T&) [with T = minimal; Archive = boost::archive::text_oarchive]'
minimal.cc:24:11: required from here
minimal.cc:11:46: warning: unused parameter 'vers' [-Wunused-parameter]
11 | void serialize(Archive & ar,const unsigned vers){
| ~~~~~~~~~~~~~~~^~~~
'''
解决方法
修复很容易,只需删除未使用的参数的名称,或注释掉它的名称。
struct minimal {
minimal()=default;
minimal(int in)
: x {in}
{}
template <typename Archive>
void serialize(Archive & ar,unsigned /*vers*/){
ar & x;
}
int x;
};
在 C++17 中,您有 [[maybe_unused]] 属性说明符,例如:
struct minimal {
minimal()=default;
minimal(int in)
: x {in}
{}
template <typename Archive>
void serialize(Archive & ar,[[maybe_unused]] unsigned ver){
ar & x;
}
int x;
};
请参阅此问题以进一步阅读: