Re: [boost] [exception] warning about non-virtual destructor - resolution?

Subject: Re: [boost] [exception] warning about non-virtual destructor - resolution?
From: Daniel James (dnljms_at_[hidden])
Date: 2012-04-18 04:41:27

On 18 April 2012 00:16, Vicente J. Botet Escriba
<vicente.botet_at_[hidden]> wrote:
>
> demo.cpp:
>
> #include<boost/checked_delete.hpp>
> #include<boost/exception_ptr.hpp>
>
> Compiled with:
>
> g++-mp-4.7 -c -Wall -I $BOOST_ROOT demo.cpp

That's the one. When testing, try explicitly using the
'-Wdelete-non-virtual-dtor' flag. That way there will be an error if
for versions of g++ that don't support it. This is a new feature and
some distributions of gcc on windows are often a bit behind linux and
mac.

The following output if from trunk revision 78061:

$ g++-mp-4.7 --version
g++-mp-4.7 (GCC) 4.7.0
Copyright (C) 2012 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

$ g++-mp-4.7 -I $BOOST_ROOT demo.cpp -c -Wdelete-non-virtual-dtor
In file included from demo.cpp:1:0:
/Users/daniel/boost/git/boost/checked_delete.hpp: In instantiation of
'void boost::checked_delete(T*) [with T =
boost::error_info<boost::tag_original_exception_type, const
std::type_info*>]':
/Users/daniel/boost/git/boost/smart_ptr/detail/shared_count.hpp:95:13:
  required from 'boost::detail::shared_count::shared_count(Y*) [with Y
= boost::error_info<boost::tag_original_exception_type, const
std::type_info*>]'
/Users/daniel/boost/git/boost/smart_ptr/shared_ptr.hpp:177:50:
required from 'boost::shared_ptr<T>::shared_ptr(Y*) [with Y =
boost::error_info<boost::tag_original_exception_type, const
std::type_info*>; T =
boost::error_info<boost::tag_original_exception_type, const
std::type_info*>]'
/Users/daniel/boost/git/boost/exception/info.hpp:171:69:   required
from 'const E& boost::exception_detail::set_info(const E&, const
boost::error_info<Tag, T>&) [with E = boost::unknown_exception; Tag =
boost::tag_original_exception_type; T = const std::type_info*]'
/Users/daniel/boost/git/boost/exception/info.hpp:192:46:   required
from 'typename boost::enable_if<boost::exception_detail::derives_boost_exception<E>,
const E&>::type boost::operator<<(const E&, const
boost::error_info<Tag, T>&) [with E = boost::unknown_exception; Tag =
boost::tag_original_exception_type; T = const std::type_info*;
typename boost::enable_if<boost::exception_detail::derives_boost_exception<E>,
const E&>::type = const boost::unknown_exception&]'
/Users/daniel/boost/git/boost/exception/detail/exception_ptr.hpp:182:13:
  required from 'void
boost::unknown_exception::add_original_type(const E&) [with E =
std::exception]'
/Users/daniel/boost/git/boost/exception/detail/exception_ptr.hpp:161:32:
  required from here
/Users/daniel/boost/git/boost/checked_delete.hpp:34:5: warning:
deleting object of polymorphic class type
'boost::error_info<boost::tag_original_exception_type, const
std::type_info*>' which has non-virtual destructor might cause
undefined behaviour [-Wdelete-non-virtual-dtor]

$ clang-mp-3.1 --version
clang version 3.1 (trunk 154872)
Target: i386-apple-darwin9.8.0
Thread model: posix

$ clang-mp-3.1 -I $BOOST_ROOT demo.cpp -c -Wdelete-non-virtual-dtor
In file included from demo.cpp:1:
/Users/daniel/boost/git/boost/checked_delete.hpp:34:5: warning: delete
called on 'boost::error_info<boost::tag_original_exception_type, const
std::type_info *>' that has virtual functions but
      non-virtual destructor [-Wdelete-non-virtual-dtor]
    delete x;
    ^
/Users/daniel/boost/git/boost/smart_ptr/detail/shared_count.hpp:95:13:
note: in instantiation of function template specialization
      'boost::checked_delete<boost::error_info<boost::tag_original_exception_type,
const std::type_info *> >' requested here
            boost::checked_delete( p );
            ^
/Users/daniel/boost/git/boost/smart_ptr/shared_ptr.hpp:177:44: note:
in instantiation of function template specialization
      'boost::detail::shared_count::shared_count<boost::error_info<boost::tag_original_exception_type,
const std::type_info *> >' requested here
    explicit shared_ptr( Y * p ): px( p ), pn( p ) // Y must be complete
                                           ^
/Users/daniel/boost/git/boost/exception/info.hpp:170:42: note: in
instantiation of function template specialization
'boost::shared_ptr<boost::error_info<boost::tag_original_exception_type,
const
      std::type_info *>
>::shared_ptr<boost::error_info<boost::tag_original_exception_type,
const std::type_info *> >' requested here
            shared_ptr<error_info_tag_t> p( new error_info_tag_t(v) );
                                         ^
/Users/daniel/boost/git/boost/exception/info.hpp:191:16: note: in
instantiation of function template specialization
'boost::exception_detail::set_info<boost::unknown_exception,
      boost::tag_original_exception_type, const std::type_info *>'
requested here
        return exception_detail::set_info(x,v);
               ^
/Users/daniel/boost/git/boost/exception/detail/exception_ptr.hpp:181:21:
note: in instantiation of function template specialization
'boost::operator<<<boost::unknown_exception,
      boost::tag_original_exception_type, const std::type_info *>'
requested here
            (*this) << original_exception_type(&typeid(e));
                    ^
/Users/daniel/boost/git/boost/exception/detail/exception_ptr.hpp:160:13:
note: in instantiation of function template specialization
'boost::unknown_exception::add_original_type<std::exception>'
      requested here
            add_original_type(e);
            ^
1 warning generated.