Use the underlying type for hashing enums

.appveyor.yml

@@ -25,10 +25,10 @@ environment:
       TOOLSET: msvc-14.1
       CXXSTD: 14,17
       ADDRMD: 32,64
-    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
-      TOOLSET: clang-win
-      ADDRMD: 64
+    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2019
+      TOOLSET: msvc-14.2
       CXXSTD: 14,17,latest
+      ADDRMD: 32,64
     - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2019
       TOOLSET: clang-win
       CXXSTD: 14,17,latest

include/boost/container_hash/hash.hpp

@@ -26,7 +26,9 @@
 #include <boost/type_traits/is_floating_point.hpp>
 #include <boost/type_traits/is_signed.hpp>
 #include <boost/type_traits/is_unsigned.hpp>
+#include <boost/type_traits/make_signed.hpp>
 #include <boost/type_traits/make_unsigned.hpp>
+#include <boost/type_traits/conditional.hpp>
 #include <boost/type_traits/enable_if.hpp>
 #include <boost/type_traits/conjunction.hpp>
 #include <boost/cstdint.hpp>
@@ -38,6 +40,10 @@
 #include <climits>
 #include <cstring>
 
+#if !defined(BOOST_NO_CXX11_HDR_TYPE_TRAITS)
+# include <type_traits>
+#endif
+
 #if !defined(BOOST_NO_CXX11_SMART_PTR)
 # include <memory>
 #endif
@@ -163,21 +169,17 @@ namespace boost
     typename boost::enable_if_<boost::is_enum<T>::value, std::size_t>::type
         hash_value( T v )
     {
-        // This should in principle return the equivalent of
-        //
-        // boost::hash_value( to_underlying(v) );
-        //
-        // However, the C++03 implementation of underlying_type,
-        //
-        // conditional<is_signed<T>, make_signed<T>, make_unsigned<T>>::type::type
-        //
-        // generates a legitimate -Wconversion warning in is_signed,
-        // because -1 is not a valid enum value when all the enumerators
-        // are nonnegative.
-        //
-        // So the legacy implementation will have to do for now.
+#if !defined(BOOST_NO_CXX11_HDR_TYPE_TRAITS)
 
-        return static_cast<std::size_t>( v );
+        typedef typename std::underlying_type<T>::type U;
+
+#else
+
+        typedef typename boost::conditional< boost::is_signed<T>::value, boost::make_signed<T>, boost::make_unsigned<T> >::type::type U;
+
+#endif
+
+        return boost::hash_value( static_cast<U>( v ) );
     }
 
     // floating point types
@@ -344,11 +346,12 @@ namespace boost
 
     // pointer types
 
-    // `x + (x >> 3)` adjustment by Alberto Barbati and Dave Harris.
+    // Implementation by Alberto Barbati and Dave Harris.
     template <class T> std::size_t hash_value( T* const& v )
     {
-        boost::uintptr_t x = reinterpret_cast<boost::uintptr_t>( v );
-        return boost::hash_value( x + (x >> 3) );
+        std::size_t x = static_cast<std::size_t>(
+           reinterpret_cast<boost::uintptr_t>(v));
+        return x + (x >> 3);
     }
 
     // array types
@@ -417,7 +420,7 @@ namespace boost
         return boost::hash_unordered_range( v.begin(), v.end() );
     }
 
-#if defined(_MSVC_STL_VERSION) && _MSVC_STL_VERSION == 141 && BOOST_CXX_VERSION >= 201700L
+#if defined(BOOST_MSVC) && BOOST_MSVC >= 1910 && BOOST_MSVC < 1920 && BOOST_CXX_VERSION >= 201700L
 
     // resolve ambiguity with unconstrained stdext::hash_value in <xhash> :-/
 
@@ -670,7 +673,7 @@ namespace boost
         }
     };
 
-#if defined(_MSVC_STL_VERSION) && _MSVC_STL_VERSION == 141 && BOOST_CXX_VERSION >= 201700L
+#if defined(BOOST_MSVC) && BOOST_MSVC >= 1910 && BOOST_MSVC < 1920 && BOOST_CXX_VERSION >= 201700L
 
     // msvc-14.1 has stdext::hash_value for basic_string in <xhash> :-/
 

test/Jamfile.v2

@@ -81,5 +81,3 @@ run hash_fs_path_test.cpp /boost//filesystem/<warnings>off : : : $(fs-path-req)
 run detail_is_range_test2.cpp : : : $(fs-path-req) ;
 
 run hash_container_test.cpp ;
-
-run hash_vector_test2.cpp ;

test/hash_vector_test2.cpp

@@ -1,48 +0,0 @@
-// Copyright 2021, 2022 Peter Dimov.
-// Distributed under the Boost Software License, Version 1.0.
-// https://www.boost.org/LICENSE_1_0.txt
-
-#if defined(__GNUC__) && __GNUC__ == 8
-# pragma GCC diagnostic ignored "-Wsign-conversion"
-#endif
-
-#include <boost/container_hash/hash.hpp>
-#include <boost/core/lightweight_test.hpp>
-#include <vector>
-#include <functional> // to catch msvc-14.1 conflicts
-
-template<class T> void test()
-{
-    typedef std::vector<T> list;
-    typedef boost::hash<list> hash;
-
-    int const N = 32;
-
-    std::size_t h[ N ];
-
-    list v;
-
-    for( int i = 0; i < N; ++i )
-    {
-        h[ i ] = hash()( v );
-
-        BOOST_TEST_EQ( h[ i ], hash()( v ) );
-
-        for( int j = 0; j < i; ++j )
-        {
-            BOOST_TEST_NE( h[ j ], h[ i ] );
-        }
-
-        v.push_back( T() );
-    }
-}
-
-int main()
-{
-    test<int>();
-    test<float>();
-    test<double>();
-    test< std::vector<int> >();
-
-    return boost::report_errors();
-}