Smart pointer and utility changes related to adding checked_delere and checked_array_delete

[SVN r10189]

checked_delete_test.cpp

@@ -0,0 +1,31 @@
+//  Boost checked_delete test program  ---------------------------------------//
+
+//  (C) Copyright Beman Dawes 2001. Permission to copy, use, modify, sell
+//  and distribute this software is granted provided this copyright
+//  notice appears in all copies. This software is provided "as is" without
+//  express or implied warranty, and with no claim as to its suitability for
+//  any purpose.
+
+//  See http://www.boost.org for most recent version including documentation.
+
+//  Revision History
+//  21 May 01  Initial version (Beman Dawes)
+
+#include <boost/utility.hpp>  // for checked_delete
+
+//  This program demonstrates compiler errors when trying to delete an
+//  incomplete type.
+
+namespace
+{
+    class Incomplete;
+}
+
+int main()
+{
+    Incomplete * p;
+    boost::checked_delete(p);          // should cause compile time error
+    Incomplete ** pa;
+    boost::checked_array_delete(pa);   // should cause compile time error
+    return 0;
+}   // main

include/boost/utility.hpp

@@ -11,6 +11,9 @@
 //  Classes appear in alphabetical order
 
 //  Revision History
+//  21 May 01  checked_delete() and checked_array_delete() added (Beman Dawes,
+//             suggested by Dave Abrahams, generalizing idea from Vladimir Prus)
+//  21 May 01  made next() and prior() inline (Beman Dawes)  
 //  26 Jan 00  protected noncopyable destructor added (Miki Jovanovic)
 //  10 Dec 99  next() and prior() templates added (Dave Abrahams)
 //  30 Aug 99  moved cast templates to cast.hpp (Beman Dawes)
@@ -22,12 +25,44 @@
 #ifndef BOOST_UTILITY_HPP
 #define BOOST_UTILITY_HPP
 
-#include <boost/config.hpp>
+#include <boost/config.hpp>        // broken compiler workarounds 
+#include <boost/static_assert.hpp> // broken compiler workarounds 
 #include <cstddef>                 // for size_t
 #include <utility>                 // for std::pair
 
 namespace boost
 {
+//  checked_delete() and checked_array_delete()  -----------------------------//
+
+    // verify that types are complete for increased safety
+
+    template< typename T >
+# if !defined(BOOST_MSVC) || BOOST_MSVC > 1200
+    inline void checked_delete(T const volatile * x)
+# else
+    inline void checked_delete(T  /*const volatile*/ * x)
+# endif
+    {
+# if !defined(__BORLANDC__) || __BORLANDC__ > 0x0551
+        BOOST_STATIC_ASSERT( sizeof(T) ); // assert type complete at point
+                                          // of instantiation
+# endif
+        delete x;
+    }
+
+    template< typename T >
+# if !defined(BOOST_MSVC) || BOOST_MSVC > 1200
+    inline void checked_array_delete(T const volatile * x)
+# else
+    inline void checked_array_delete(T  /*const volatile*/ * x)
+# endif
+    {
+# if !defined(__BORLANDC__) || __BORLANDC__ > 0x0551
+        BOOST_STATIC_ASSERT( sizeof(T) ); // assert type complete at point
+                                          // of instantiation
+# endif
+        delete [] x;
+    }
 
 //  next() and prior() template functions  -----------------------------------//
 
@@ -41,10 +76,10 @@ namespace boost
     //  Contributed by Dave Abrahams
 
     template <class T>
-    T next(T x) { return ++x; }
+    inline T next(T x) { return ++x; }
 
     template <class T>
-    T prior(T x) { return --x; }
+    inline T prior(T x) { return --x; }
 
 
 //  class noncopyable  -------------------------------------------------------//

utility.htm

@@ -16,10 +16,50 @@
 <h2>Contents</h2>
 
 <ul>
+  <li>Function templates <a href="#checked_delete">checked_delete() and
+    checked_array_delete()</a></li>
   <li>Function templates <a href="#functions next">next() and prior()</a></li>
   <li>Class <a href="#Class noncopyable">noncopyable</a></li>
   <li>Function template <a href="tie.html">tie()</a> and supporting class tied.</li>
 </ul>
+<h2> Function templates <a name="checked_delete">checked_delete</a>() and
+checked_array_delete()</h2>
+
+<p>Deletion of a pointer to an incomplete type is an unsafe programming practice
+because there is no way for the compiler to verify that the destructor is indeed
+trivial.&nbsp; The checked_delete() and checked_array_delete() function
+templates simply <b>delete</b> or <b>delete[]</b> their argument, but also
+require that their argument be a complete type.&nbsp; They issue an appropriate
+compiler error diagnostic if that requirement is not met.&nbsp; A typical
+implementation is shown; other implementations may vary:</p>
+
+<pre>    template&lt; typename T &gt;
+    inline void checked_delete(T const volatile * x)
+    {
+        BOOST_STATIC_ASSERT( sizeof(T) ); // assert type complete at point
+                                          // of instantiation
+        delete x;
+    }
+
+    template&lt; typename T &gt;
+    inline void checked_array_delete(T const volatile * x)
+    {
+        BOOST_STATIC_ASSERT( sizeof(T) ); // assert type complete at point
+                                          // of instantiation
+        delete [] x;
+    }</pre>
+
+<p>Contributed by Beman Dawes, based on a suggestion from Dave Abrahams,
+generalizing an idea from Vladimir Prus, with comments from Rainer Deyke, John
+Maddock, and others.</p>
+
+<h3>Background</h3>
+
+<p>The C++ Standard specifies that delete on a pointer to an incomplete types is
+undefined behavior if the type has a non-trivial destructor in&nbsp; [expr.delete]
+5.3.5 paragraph.&nbsp; No diagnostic is required.&nbsp; Some but not all
+compilers issue warnings if the type is incomplete at point of deletion.</p>
+
 <h2> <a name="functions next">Function</a> templates next() and prior()</h2>
 
 <p>Certain data types, such as the C++ Standard Library's forward and
@@ -91,9 +131,11 @@ emphasize that it is to be used only as a base class.&nbsp; Dave Abrahams notes
 concern about the effect on compiler optimization of adding (even trivial inline)
 destructor declarations. He says &quot;Probably this concern is misplaced, because
 noncopyable will be used mostly for classes which own resources and thus have non-trivial destruction semantics.&quot;</p>
+<h2>Function template tie()</h2>
+<p>See <a href="tie.html">separate documentation</a>.</p>
 <hr>
 <p>Revised&nbsp; <!--webbot bot="Timestamp" S-Type="EDITED" S-Format="%d %B, %Y" startspan
--->08 March, 2001<!--webbot bot="Timestamp" endspan i-checksum="28780"
+-->22 May, 2001<!--webbot bot="Timestamp" endspan i-checksum="13960"
 -->
 </p>
 <p>© Copyright boost.org 1999. Permission to copy, use, modify, sell and