Merge branch 'feature/issue-26-nofix' into feature/issue-26

include/boost/variant2/variant.hpp

@@ -26,7 +26,6 @@
 #include <initializer_list>
 #include <utility>
 #include <functional> // std::hash
-#include <cstdint>
 
 //
 
@@ -39,8 +38,6 @@ BOOST_NORETURN void throw_exception( std::exception const & e ); // user defined
 
 #endif
 
-template<class T> struct hash;
-
 namespace variant2
 {
 
@@ -1584,7 +1581,7 @@ public:
 
     template<class U,
         class Ud = typename std::decay<U>::type,
-        class E1 = typename std::enable_if< !std::is_same<Ud, variant>::value && !detail::is_in_place_index<Ud>::value && !detail::is_in_place_type<Ud>::value >::type,
+        class E1 = typename std::enable_if< !std::is_same<Ud, variant>::value && !std::is_base_of<variant, Ud>::value && !detail::is_in_place_index<Ud>::value && !detail::is_in_place_type<Ud>::value >::type,
         class V = detail::resolve_overload_type<U&&, T...>,
         class E2 = typename std::enable_if<std::is_constructible<V, U&&>::value>::type
         >
@@ -2198,59 +2195,31 @@ void swap( variant<T...> & v, variant<T...> & w )
 namespace detail
 {
 
-inline std::size_t hash_value_impl_( mp11::mp_true, std::size_t index, std::size_t value )
-{
-    boost::ulong_long_type hv = ( boost::ulong_long_type( 0xCBF29CE4 ) << 32 ) + 0x84222325;
-    boost::ulong_long_type const prime = ( boost::ulong_long_type( 0x00000100 ) << 32 ) + 0x000001B3;
-
-    hv ^= index;
-    hv *= prime;
-
-    hv ^= value;
-    hv *= prime;
-
-    return static_cast<std::size_t>( hv );
-}
-
-inline std::size_t hash_value_impl_( mp11::mp_false, std::size_t index, std::size_t value )
-{
-    std::size_t hv = 0x811C9DC5;
-    std::size_t const prime = 0x01000193;
-
-    hv ^= index;
-    hv *= prime;
-
-    hv ^= value;
-    hv *= prime;
-
-    return hv;
-}
-
-inline std::size_t hash_value_impl( std::size_t index, std::size_t value )
-{
-    return hash_value_impl_( mp11::mp_bool< (SIZE_MAX > UINT32_MAX) >(), index, value );
-}
-
-template<template<class> class H, class V> struct hash_value_L
+template<class V> struct hash_value_L
 {
     V const & v;
 
     template<class I> std::size_t operator()( I ) const
     {
+        boost::ulong_long_type hv = ( boost::ulong_long_type( 0xCBF29CE4 ) << 32 ) + 0x84222325;
+        boost::ulong_long_type const prime = ( boost::ulong_long_type( 0x00000100 ) << 32 ) + 0x000001B3;
+
+        // index
+
+        hv ^= I::value;
+        hv *= prime;
+
+        // value
+
         auto const & t = unsafe_get<I::value>( v );
 
-        std::size_t index = I::value;
-        std::size_t value = H<remove_cv_ref_t<decltype(t)>>()( t );
+        hv ^= std::hash<remove_cv_ref_t<decltype(t)>>()( t );
+        hv *= prime;
 
-        return hash_value_impl( index, value );
+        return static_cast<std::size_t>( hv );
     }
 };
 
-template<class... T> std::size_t hash_value_std( variant<T...> const & v )
-{
-    return mp11::mp_with_index<sizeof...(T)>( v.index(), detail::hash_value_L< std::hash, variant<T...> >{ v } );
-}
-
 } // namespace detail
 
 inline std::size_t hash_value( monostate const & )
@@ -2260,7 +2229,7 @@ inline std::size_t hash_value( monostate const & )
 
 template<class... T> std::size_t hash_value( variant<T...> const & v )
 {
-    return mp11::mp_with_index<sizeof...(T)>( v.index(), detail::hash_value_L< boost::hash, variant<T...> >{ v } );
+    return mp11::mp_with_index<sizeof...(T)>( v.index(), detail::hash_value_L< variant<T...> >{ v } );
 }
 
 namespace detail
@@ -2281,7 +2250,7 @@ template<class V> struct std_hash_impl<V, true>
 {
     std::size_t operator()( V const & v ) const
     {
-        return detail::hash_value_std( v );
+        return hash_value( v );
     }
 };
 

test/Jamfile

@@ -119,3 +119,5 @@ run variant_visit_r.cpp : : :
     <toolset>gcc,<target-os>windows:<variant>release
     <toolset>gcc,<target-os>cygwin:<variant>release
     ;
+
+compile variant_derived_construct.cpp ;

test/variant_derived_construct.cpp

@@ -0,0 +1,33 @@
+// Copyright 2021 Peter Dimov.
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/variant2/variant.hpp>
+
+using namespace boost::variant2;
+
+template<class... T> class X: variant<T...>
+{
+    using base = variant<T...>;
+    using base::base;
+};
+
+struct Y
+{
+    Y( Y const& rhs ) = default;
+
+    template<class T> Y( T const& t )
+    {
+        t.bar();
+    }
+};
+
+int main()
+{
+    using W = X<int, double, Y>;
+
+    W a( 1 );
+    W b( a );
+
+    (void)b;
+}

test/variant_hash.cpp

@@ -12,7 +12,6 @@
 #include <boost/core/lightweight_test_trait.hpp>
 #include <boost/container_hash/hash.hpp>
 #include <boost/config/workaround.hpp>
-#include <vector>
 
 using namespace boost::variant2;
 
@@ -48,17 +47,7 @@ template<template<class...> class Hash, class T> void test2()
     BOOST_TEST_NE( h2, h3 );
 }
 
-struct X
-{
-    int m = 0;
-};
-
-std::size_t hash_value( X const& x )
-{
-    return boost::hash<int>()( x.m );
-}
-
-struct Y {}; // no hash support
+struct X {};
 
 int main()
 {
@@ -68,8 +57,6 @@ int main()
     test<boost::hash, monostate, monostate, monostate>();
     test<boost::hash, int, int, float>();
 
-    test<boost::hash, monostate, X, std::vector<X>>();
-
     test2<std::hash, int>();
     test2<std::hash, float>();
 
@@ -78,7 +65,7 @@ int main()
 
 #if !BOOST_WORKAROUND(BOOST_MSVC, < 1910) && ( !defined(_LIBCPP_STD_VER) || _LIBCPP_STD_VER > 11 )
 
-    BOOST_TEST_TRAIT_FALSE(( detail::is_hash_enabled<Y> ));
+    BOOST_TEST_TRAIT_FALSE(( detail::is_hash_enabled<X> ));
 
 #endif