[Boost-bugs] [Boost C++ Libraries] #1444: scoped_ptr::operator== should be equivalent to a.get()==b.get(), but is currently !!a==!!b

Subject: [Boost-bugs] [Boost C++ Libraries] #1444: scoped_ptr::operator== should be equivalent to a.get()==b.get(), but is currently !!a==!!b
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2007-11-15 16:26:49

#1444: scoped_ptr::operator== should be equivalent to a.get()==b.get(), but is
currently !!a==!!b
----------------------------------------------+-----------------------------
 Reporter:  Geoffrey Irving <irving_at_[hidden]>  |        Type:  Bugs            
   Status:  new                               |   Milestone:  To Be Determined
Component:  None                              |     Version:  Boost 1.34.1    
 Severity:  Problem                           |    Keywords:                  
----------------------------------------------+-----------------------------
 scoped_ptr<T> does not define an explicit operator==, so an equality test
 between two
 of them falls back to using the implicit conversion to bool.  Here's a
 program illustrating
 the bug:

 {{{
 #include <boost/scoped_ptr.hpp>

 int main()
 {
     boost::scoped_ptr<int> a1(new int),a2(new int);
     BOOST_ASSERT(a1!=a2); // fails
     BOOST_ASSERT(!(a1==a2)); // fails
 }
 }}}

 This is a significant bug, since it results in silent failures when
 converting programs
 using normal pointers to scoped_ptr.  Adding definitions for operator==
 and operator!=
 fixes the problem:

 {{{
 template<class T> inline bool operator==(const scoped_ptr<T>& p, const
 scoped_ptr<T>& q)
 {
     return p.get()==q.get();
 }

 template<class T> inline bool operator!=(const scoped_ptr<T>& p, const
 scoped_ptr<T>& q)
 {
     return p.get()!=q.get();
 }
 }}}

 I verified that the comparison operators (e.g., <), do not compile, which
 is fine.

-- 
Ticket URL: <http://svn.boost.org/trac/boost/ticket/1444>
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