New, improved and more portable unspecified bool type. I hope.

[SVN r33987]

include/boost/shared_ptr.hpp

@@ -323,6 +323,8 @@ public:
 
     // implicit conversion to "bool"
 
+/*
+
 #if defined(__SUNPRO_CC) && BOOST_WORKAROUND(__SUNPRO_CC, <= 0x530)
 
     operator bool () const
@@ -330,6 +332,23 @@ public:
         return px != 0;
     }
 
+#elif defined( _MANAGED )
+
+*/
+
+    static void unspecified_bool( this_type*** )
+    {
+    }
+
+    typedef void (*unspecified_bool_type)( this_type*** );
+
+    operator unspecified_bool_type() const // never throws
+    {
+        return px == 0? 0: unspecified_bool;
+    }
+
+/*
+
 #elif \
     ( defined(__MWERKS__) && BOOST_WORKAROUND(__MWERKS__, < 0x3200) ) || \
     ( defined(__GNUC__) && (__GNUC__ * 100 + __GNUC_MINOR__ < 304) )
@@ -352,6 +371,8 @@ public:
 
 #endif
 
+*/
+
     // operator! is redundant, but some compilers need it
 
     bool operator! () const // never throws