Merge iostreams, hash.

Including disallowing implicit casts to `hash_value`.


[SVN r63812]

hash/doc/changes.qbk

@@ -106,4 +106,12 @@
   Avoid hashing 0.5 and 0 to the same number.
 * Stop using deprecated `BOOST_HAS_*` macros.
 
+[h2 Boost 1.44.0]
+
+* Prevent implicit conversions when calling `hash_value`. If you find
+  that the new version breaks your code, you can enable the old
+  behaviour by defining `BOOST_HASH_ALLOW_IMPLICIT_CASTS` - although
+  I would recommend that you update your code to work with the new
+  version.
+
 [endsect]

hash/test/Jamfile.v2

@@ -50,6 +50,8 @@ test-suite functional/hash
         [ run container_no_fwd_test.cpp ]
         [ compile-fail hash_no_ext_fail_test.cpp ]
         [ compile-fail namespace_fail_test.cpp ]
+        [ compile-fail implicit_fail_test.cpp ]
+        [ compile-fail shared_ptr_fail_test.cpp ]
         [ run hash_no_ext_macro_1.cpp ]
         [ run hash_no_ext_macro_2.cpp ]
     ;

hash/test/implicit_fail_test.cpp

@@ -0,0 +1,21 @@
+
+// Copyright 2010 Daniel James.
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+
+#include <boost/functional/hash.hpp>
+
+namespace test
+{
+    struct base {};
+    std::size_t hash_value(base const&) { return 0; }
+    
+    struct converts { operator base() const { return base(); } };
+}
+
+int main() {
+    boost::hash<test::converts> hash;
+    test::converts x;
+    
+    hash(x);
+}

hash/test/shared_ptr_fail_test.cpp

@@ -0,0 +1,16 @@
+
+// Copyright 2010 Daniel James.
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+
+#include <boost/functional/hash.hpp>
+#include <boost/shared_ptr.hpp>
+
+// This should obviously pass if shared_ptr ever supports Boost.Hash.
+
+int main() {
+    boost::hash<boost::shared_ptr<int> > hash;
+    boost::shared_ptr<int> x(new int(10));
+    
+    hash(x);
+}

include/boost/functional/hash/hash.hpp

@@ -15,6 +15,7 @@
 #include <boost/functional/hash/detail/hash_float.hpp>
 #include <string>
 #include <boost/limits.hpp>
+#include <boost/static_assert.hpp>
 
 #if defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION)
 #include <boost/type_traits/is_pointer.hpp>
@@ -29,6 +30,18 @@
 
 namespace boost
 {
+#if !defined(BOOST_HASH_ALLOW_IMPLICIT_CASTS)
+
+    // If you get a static assertion here, it's because hash_value
+    // isn't declared for your type.
+    template <typename T>
+    std::size_t hash_value(T const&) {
+        BOOST_STATIC_ASSERT((T*) 0 && false);
+        return 0;
+    }
+
+#endif
+
     std::size_t hash_value(bool);
     std::size_t hash_value(char);
     std::size_t hash_value(unsigned char);