Merge branch 'develop' (early part)

include/boost/functional/forward_adapter.hpp

@@ -144,8 +144,30 @@ namespace boost
             : boost::result_of< BOOST_DEDUCED_TYPENAME c<Self>::t() >
         { };
 
-        template< class MD, class F, class FC >
-        struct forward_adapter_impl<MD,F,FC,0,0>
+        // WHen operator()() doesn't have any parameters, it can't
+        // be templatized and can't use SFINAE, so intead use class
+        // template parameter SFINAE to decide whether to instantiate it.
+
+        template <typename T, typename R = void>
+        struct forward_adapter_sfinae
+        {
+            typedef T type;
+        };
+
+        // This is the fallback for when there isn't an operator()(),
+        // need to create an operator() that will never instantiate
+        // so that using parent::operator() will work okay.
+        template< class MD, class F, class FC, class Enable = void>
+        struct forward_adapter_impl_zero
+        {
+            template <typename T> struct never_instantiate {};
+            template <typename T>
+            typename never_instantiate<T>::type operator()(T) const {}
+        };
+
+        template< class MD, class F, class FC>
+        struct forward_adapter_impl_zero<MD, F, FC,
+            typename forward_adapter_sfinae<typename boost::result_of< FC() >::type>::type>
         {
             inline typename boost::result_of< FC() >::type
             operator()() const
@@ -158,6 +180,13 @@ namespace boost
             {
                 return static_cast<MD*>(this)->target_function()();
             }
+        };
+
+        template< class MD, class F, class FC >
+        struct forward_adapter_impl<MD,F,FC,0,0>
+            : forward_adapter_impl_zero<MD,F,FC>
+        {
+            using forward_adapter_impl_zero<MD,F,FC>::operator();
 
         // closing brace gets generated by preprocessing code, below
 

include/boost/functional/hash/hash.hpp

@@ -212,7 +212,6 @@ namespace boost
             seed ^= value + 0x9e3779b9 + (seed<<6) + (seed>>2);
         }
 
-        template <typename SizeT>
         inline void hash_combine_impl(boost::uint32_t& h1,
                 boost::uint32_t k1)
         {
@@ -229,12 +228,11 @@ namespace boost
         }
 
 
-// Don't define 64-bit hash combine on platforms with 64 bit integers,
+// Don't define 64-bit hash combine on platforms without 64 bit integers,
 // and also not for 32-bit gcc as it warns about the 64-bit constant.
 #if !defined(BOOST_NO_INT64_T) && \
         !(defined(__GNUC__) && ULONG_MAX == 0xffffffff)
 
-        template <typename SizeT>
         inline void hash_combine_impl(boost::uint64_t& h,
                 boost::uint64_t k)
         {
@@ -247,6 +245,10 @@ namespace boost
 
             h ^= k;
             h *= m;
+
+            // Completely arbitrary number, to prevent 0's
+            // from hashing to 0.
+            h += 0xe6546b64;
         }
 
 #endif // BOOST_NO_INT64_T

include/boost/functional/lightweight_forward_adapter.hpp

@@ -149,8 +149,31 @@ namespace boost
             : boost::result_of< BOOST_DEDUCED_TYPENAME c<Self>::t() >
         { };
 
-        template< class MD, class F, class FC >
-        struct lightweight_forward_adapter_impl<MD,F,FC,0,0>
+        // When operator() doesn't have any parameters, it can't
+        // be templatized and can't use SFINAE, so intead use class
+        // template parameter SFINAE to decide whether to instantiate it.
+
+        template <typename T, typename R = void>
+        struct lightweight_forward_adapter_sfinae
+        {
+            typedef T type;
+        };
+
+        // This is the fallback for when there isn't an operator()(),
+        // need to create an operator() that will never instantiate
+        // so that using parent::operator() will work okay.
+        template< class MD, class F, class FC, class Enable = void>
+        struct lightweight_forward_adapter_impl_zero
+            : lightweight_forward_adapter_result
+        {
+            template <typename T> struct never_instantiate {};
+            template <typename T>
+            typename never_instantiate<T>::type operator()(T) const {}
+        };
+
+        template< class MD, class F, class FC>
+        struct lightweight_forward_adapter_impl_zero<MD, F, FC,
+            typename lightweight_forward_adapter_sfinae<typename boost::result_of< FC() >::type>::type>
             : lightweight_forward_adapter_result
         {
             inline typename boost::result_of< FC() >::type
@@ -166,6 +189,12 @@ namespace boost
             }
         };
 
+        template< class MD, class F, class FC >
+        struct lightweight_forward_adapter_impl<MD,F,FC,0,0>
+            : lightweight_forward_adapter_impl_zero<MD,F,FC>
+        {
+        };
+
 #       define  BOOST_PP_FILENAME_1 \
             <boost/functional/lightweight_forward_adapter.hpp>
 #       define  BOOST_PP_ITERATION_LIMITS                                     \