[boost] [exception] Virtual destructor warnings (again)

Subject: [boost] [exception] Virtual destructor warnings (again)
From: Chris Newbold (Chris.Newbold_at_[hidden])
Date: 2008-09-11 06:51:03

I'm running into another instance of virtual destructor warnings with Boost.Exception -- this one when building on Solaris using the Sun Studio 12 compiler.

The problem is with the boost::exception_detail::exception_clone class template. It uses CRTP and is often instantiated with a type which has a virtual destructor which has been declared 'throw()'.

This causes the compiler to complain that the exception specification for exception_clone's implicitly-generated destructor is too wide:

"../../../3p_mirror/sol64/boost/include/boost-1_36/boost/exception/enable_current_exception.hpp", line 121: Warning, wlessrestrictedthrow: Function boost::exception_detail::exception_clone<boost::exception_detail::error_info_injector<boost::bad_function_call>>::~exception_clone() can throw only the exceptions thrown by the function boost::exception_detail::error_info_injector<boost::bad_function_call>::~error_info_injector() it overrides.
"../../../3p_mirror/sol64/boost/include/boost-1_36/boost/exception/enable_current_exception.hpp", line 130:     Where, temwhilespec: While specializing "boost::exception_detail::exception_clone<boost::exception_detail::error_info_injector<boost::bad_function_call>>".
"../../../3p_mirror/sol64/boost/include/boost-1_36/boost/exception/enable_current_exception.hpp", line 130:     Where, teminstfrom: Instantiated from boost::function3<void, int&, const char**&, const char**>::operator()(int&, const char**&, const char**) const.
"../../../3p_mirror/sol64/boost/include/boost-1_36/boost/signals/signal_template.hpp", line 119:     Where, teminstfrom: Instantiated from boost::signal3<void, int&, const char**&, const char**, boost::last_value<void>, int, std::less<int>, boost::function<void(int&,const char**&,const char**)>>::operator()(int&, const char**&, const char**).

The fix seems simple enough, and is compatible with other compilers: add an empty destructor declared 'throw()' to exception_clone. Here's the diff:

==== //3rdparty/tmw/boost/boost/exception/enable_current_exception.hpp#1 - /mathworks/devel/sandbox/cnewbold/3rdp/3p/sources/boost/boost/exception/enable_current_exception.hpp ====
@@ -96,6 +96,10 @@
                         *be1 = *be2;
                 }

+           ~exception_clone() throw()
+               {
+               }
+
             private:

             detail::atomic_count mutable count_;

-Chris