Disable C4702 (unreachable code) for the throwing tests

docs: sizeof(T...) -> sizeof...(T)

README.md

@@ -14,7 +14,7 @@ Boost.Config.
 
 The repository is intended to be placed into the `libs/variant2` directory of
 a Boost clone or release, but the header `variant.hpp` will also work
-[standalone](https://godbolt.org/z/6LSV3Z).
+[standalone](https://godbolt.org/z/CTZztA).
 
 Supported compilers:
 

benchmark/benchmark1.cpp

@@ -0,0 +1,168 @@
+// Copyright 2019 Peter Dimov
+//
+// 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
+
+#if defined(ONLY_V2)
+# define NO_BV
+# define NO_SV
+#endif
+
+#if defined(ONLY_BV)
+# define NO_V2
+# define NO_SV
+#endif
+
+#if defined(ONLY_SV)
+# define NO_V2
+# define NO_BV
+#endif
+
+#if !defined(NO_V2)
+#include <boost/variant2/variant.hpp>
+#endif
+
+#if !defined(NO_BV)
+#include <boost/variant.hpp>
+#endif
+
+#if !defined(NO_SV)
+#include <variant>
+#endif
+
+#include <type_traits>
+#include <chrono>
+#include <iostream>
+#include <iomanip>
+#include <vector>
+#include <map>
+#include <string>
+#include <stdexcept>
+
+template<class T> struct is_numeric: std::integral_constant<bool, std::is_integral<T>::value || std::is_floating_point<T>::value>
+{
+};
+
+template<class T, class U> struct have_addition: std::integral_constant<bool, is_numeric<T>::value && is_numeric<U>::value>
+{
+};
+
+template<class T, class U, class E = std::enable_if_t<have_addition<T, U>::value>> auto add( T const& t, U const& u )
+{
+    return t + u;
+}
+
+template<class T, class U, class E = std::enable_if_t<!have_addition<T, U>::value>> double add( T const& /*t*/, U const& /*u*/ )
+{
+    throw std::logic_error( "Invalid addition" );
+}
+
+inline double to_double( double const& v )
+{
+    return v;
+}
+
+#if !defined(NO_V2)
+
+template<class... T> boost::variant2::variant<T...> operator+( boost::variant2::variant<T...> const& v1, boost::variant2::variant<T...> const& v2 )
+{
+    return visit( [&]( auto const& x1, auto const & x2 ) -> boost::variant2::variant<T...> { return add( x1, x2 ); }, v1, v2 );
+}
+
+template<class... T> double to_double( boost::variant2::variant<T...> const& v )
+{
+    return boost::variant2::get<double>( v );
+}
+
+#endif
+
+#if !defined(NO_BV)
+
+template<class... T> boost::variant<T...> operator+( boost::variant<T...> const& v1, boost::variant<T...> const& v2 )
+{
+    return boost::apply_visitor( [&]( auto const& x1, auto const & x2 ) -> boost::variant<T...> { return add( x1, x2 ); }, v1, v2 );
+}
+
+template<class... T> double to_double( boost::variant<T...> const& v )
+{
+    return boost::get<double>( v );
+}
+
+#endif
+
+#if !defined(NO_SV)
+
+template<class... T> std::variant<T...> operator+( std::variant<T...> const& v1, std::variant<T...> const& v2 )
+{
+    return visit( [&]( auto const& x1, auto const & x2 ) -> std::variant<T...> { return add( x1, x2 ); }, v1, v2 );
+}
+
+template<class... T> double to_double( std::variant<T...> const& v )
+{
+    return std::get<double>( v );
+}
+
+#endif
+
+template<class V> void test_( long long N )
+{
+    std::vector<V> w;
+    // lack of reserve is deliberate
+
+    auto tp1 = std::chrono::high_resolution_clock::now();
+
+    for( long long i = 0; i < N; ++i )
+    {
+        V v;
+
+        if( i % 7 == 0 )
+        {
+            v = i / 7;
+        }
+        else
+        {
+            v = i / 7.0;
+        }
+
+        w.push_back( v );
+    }
+
+    V s = 0.0;
+
+    for( long long i = 0; i < N; ++i )
+    {
+        s = s + w[ i ];
+    }
+
+    auto tp2 = std::chrono::high_resolution_clock::now();
+
+    std::cout << std::setw( 6 ) << std::chrono::duration_cast<std::chrono::milliseconds>( tp2 - tp1 ).count() << " ms; S=" << to_double( s ) << "\n";
+}
+
+template<class... T> void test( long long N )
+{
+    std::cout << "N=" << N << ":\n";
+
+    std::cout << "        double: "; test_<double>( N );
+#if !defined(NO_V2)
+    std::cout << "      variant2: "; test_<boost::variant2::variant<T...>>( N );
+#endif
+#if !defined(NO_BV)
+    std::cout << "boost::variant: "; test_<boost::variant<T...>>( N );
+#endif
+#if !defined(NO_SV)
+    std::cout << "  std::variant: "; test_<std::variant<T...>>( N );
+#endif
+
+    std::cout << '\n';
+}
+
+int main()
+{
+    long long const N = 100'000'000LL;
+
+    test<long long, double>( N );
+    test<std::nullptr_t, long long, double, std::string, std::vector<std::string>, std::map<std::string, std::string>>( N );
+}

benchmark/benchmark1.md

@@ -0,0 +1,267 @@
+# benchmark1.cpp results
+
+## VS 2017 15.9.7 64 bit (cl.exe 19.16, /EHsc /std:c++17)
+
+### /Od
+
+#### Compile time
+
+```
+      variant2 (-DONLY_V2): 1837 ms
+boost::variant (-DONLY_BV): 2627 ms
+  std::variant (-DONLY_SV): 1425 ms
+```
+
+#### Run time
+
+```
+N=100000000:
+        double:   9041 ms; S=7.14286e+14
+      variant2:  48367 ms; S=7.14286e+14
+boost::variant: 102776 ms; S=7.14286e+14
+  std::variant:  40590 ms; S=7.14286e+14
+
+N=100000000:
+        double:   9029 ms; S=7.14286e+14
+      variant2:  92962 ms; S=7.14286e+14
+boost::variant: 110441 ms; S=7.14286e+14
+  std::variant:  92974 ms; S=7.14286e+14
+```
+
+### /O2 /DNDEBUG
+
+#### Compile time
+
+```
+      variant2 (-DONLY_V2): 2571 ms
+boost::variant (-DONLY_BV): 3335 ms
+  std::variant (-DONLY_SV): 1903 ms
+```
+
+#### Run time
+
+```
+N=100000000:
+        double:   1949 ms; S=7.14286e+14
+      variant2:   4176 ms; S=7.14286e+14
+boost::variant:  11312 ms; S=7.14286e+14
+  std::variant:   4617 ms; S=7.14286e+14
+
+N=100000000:
+        double:   1949 ms; S=7.14286e+14
+      variant2:  11807 ms; S=7.14286e+14
+boost::variant:  15632 ms; S=7.14286e+14
+  std::variant:  10725 ms; S=7.14286e+14
+```
+
+## g++ 7.4.0 -std=c++17 (Cygwin 64 bit)
+
+### -O0
+
+#### Compile time
+
+```
+      variant2 (-DONLY_V2): 2734 ms
+boost::variant (-DONLY_BV): 4308 ms
+  std::variant (-DONLY_SV): 2298 ms
+```
+
+#### Run time
+
+```
+N=100000000:
+        double:   3620 ms; S=7.14286e+14
+      variant2:  29214 ms; S=7.14286e+14
+boost::variant:  88492 ms; S=7.14286e+14
+  std::variant:  39510 ms; S=7.14286e+14
+
+N=100000000:
+        double:   3642 ms; S=7.14286e+14
+      variant2:  75822 ms; S=7.14286e+14
+boost::variant:  96680 ms; S=7.14286e+14
+  std::variant:  66411 ms; S=7.14286e+14
+```
+
+### -O1
+
+#### Compile time
+
+```
+      variant2 (-DONLY_V2): 2103 ms
+boost::variant (-DONLY_BV): 3398 ms
+  std::variant (-DONLY_SV): 1841 ms
+```
+
+#### Run time
+
+```
+N=100000000:
+        double:   1576 ms; S=7.14286e+14
+      variant2:   3424 ms; S=7.14286e+14
+boost::variant:   4356 ms; S=7.14286e+14
+  std::variant:   3764 ms; S=7.14286e+14
+
+N=100000000:
+        double:   1582 ms; S=7.14286e+14
+      variant2:   9062 ms; S=7.14286e+14
+boost::variant:   9603 ms; S=7.14286e+14
+  std::variant:   8825 ms; S=7.14286e+14
+```
+
+### -O2 -DNDEBUG
+
+#### Compile time
+
+```
+      variant2 (-DONLY_V2): 2276 ms
+boost::variant (-DONLY_BV): 3647 ms
+  std::variant (-DONLY_SV): 2111 ms
+```
+
+#### Run time
+
+```
+N=100000000:
+        double:   1643 ms; S=7.14286e+14
+      variant2:   3070 ms; S=7.14286e+14
+boost::variant:   3385 ms; S=7.14286e+14
+  std::variant:   3880 ms; S=7.14286e+14
+
+N=100000000:
+        double:   1622 ms; S=7.14286e+14
+      variant2:   8101 ms; S=7.14286e+14
+boost::variant:   8611 ms; S=7.14286e+14
+  std::variant:   8694 ms; S=7.14286e+14
+```
+
+### -O3 -DNDEBUG
+
+#### Compile time
+
+```
+      variant2 (-DONLY_V2): 2390 ms
+boost::variant (-DONLY_BV): 3768 ms
+  std::variant (-DONLY_SV): 2094 ms
+```
+
+#### Run time
+
+```
+N=100000000:
+        double:   1611 ms; S=7.14286e+14
+      variant2:   2975 ms; S=7.14286e+14
+boost::variant:   3232 ms; S=7.14286e+14
+  std::variant:   3726 ms; S=7.14286e+14
+
+N=100000000:
+        double:   1603 ms; S=7.14286e+14
+      variant2:   8157 ms; S=7.14286e+14
+boost::variant:   8419 ms; S=7.14286e+14
+  std::variant:   8659 ms; S=7.14286e+14
+```
+
+## clang++ 5.0.1 -std=c++17 -stdlib=libc++ (Cygwin 64 bit)
+
+### -O0
+
+#### Compile time
+
+```
+      variant2 (-DONLY_V2): 2190 ms
+boost::variant (-DONLY_BV): 3537 ms
+  std::variant (-DONLY_SV): 2151 ms
+```
+
+#### Run time
+
+```
+N=100000000:
+        double:   6063 ms; S=7.14286e+14
+      variant2:  23616 ms; S=7.14286e+14
+boost::variant:  92730 ms; S=7.14286e+14
+  std::variant:  23160 ms; S=7.14286e+14
+
+N=100000000:
+        double:   6054 ms; S=7.14286e+14
+      variant2:  52738 ms; S=7.14286e+14
+boost::variant:  96896 ms; S=7.14286e+14
+  std::variant:  72595 ms; S=7.14286e+14
+```
+
+### -O1
+
+#### Compile time
+
+```
+      variant2 (-DONLY_V2): 2722 ms
+boost::variant (-DONLY_BV): 4337 ms
+  std::variant (-DONLY_SV): 2697 ms
+```
+
+#### Run time
+
+```
+N=100000000:
+        double:   2171 ms; S=7.14286e+14
+      variant2:   9280 ms; S=7.14286e+14
+boost::variant:  51478 ms; S=7.14286e+14
+  std::variant:   5642 ms; S=7.14286e+14
+
+N=100000000:
+        double:   2171 ms; S=7.14286e+14
+      variant2:  22166 ms; S=7.14286e+14
+boost::variant:  54084 ms; S=7.14286e+14
+  std::variant:  14330 ms; S=7.14286e+14
+```
+
+### -O2 -DNDEBUG
+
+#### Compile time
+
+```
+      variant2 (-DONLY_V2): 2499 ms
+boost::variant (-DONLY_BV): 3826 ms
+  std::variant (-DONLY_SV): 2645 ms
+```
+
+#### Run time
+
+```
+N=100000000:
+        double:   1604 ms; S=7.14286e+14
+      variant2:   2726 ms; S=7.14286e+14
+boost::variant:   6662 ms; S=7.14286e+14
+  std::variant:   3869 ms; S=7.14286e+14
+
+N=100000000:
+        double:   1598 ms; S=7.14286e+14
+      variant2:   8136 ms; S=7.14286e+14
+boost::variant:   9236 ms; S=7.14286e+14
+  std::variant:   6279 ms; S=7.14286e+14
+```
+
+### -O3 -DNDEBUG
+
+#### Compile time
+
+```
+      variant2 (-DONLY_V2): 2509 ms
+boost::variant (-DONLY_BV): 3845 ms
+  std::variant (-DONLY_SV): 2638 ms
+```
+
+#### Run time
+
+```
+N=100000000:
+        double:   1592 ms; S=7.14286e+14
+      variant2:   2697 ms; S=7.14286e+14
+boost::variant:   6648 ms; S=7.14286e+14
+  std::variant:   3826 ms; S=7.14286e+14
+
+N=100000000:
+        double:   1614 ms; S=7.14286e+14
+      variant2:   8035 ms; S=7.14286e+14
+boost::variant:   9221 ms; S=7.14286e+14
+  std::variant:   6319 ms; S=7.14286e+14
+```

benchmark/benchmark2.cpp

@@ -0,0 +1,149 @@
+// Copyright 2019 Peter Dimov
+//
+// 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
+
+#if defined(ONLY_V2)
+# define NO_BV
+# define NO_SV
+#endif
+
+#if defined(ONLY_BV)
+# define NO_V2
+# define NO_SV
+#endif
+
+#if defined(ONLY_SV)
+# define NO_V2
+# define NO_BV
+#endif
+
+#if !defined(NO_V2)
+#include <boost/variant2/variant.hpp>
+#endif
+
+#if !defined(NO_BV)
+#include <boost/variant.hpp>
+#endif
+
+#if !defined(NO_SV)
+#include <variant>
+#endif
+
+#include <type_traits>
+#include <chrono>
+#include <iostream>
+#include <iomanip>
+#include <vector>
+
+struct prefix
+{
+    int v_;
+};
+
+struct X1: prefix {};
+struct X2: prefix {};
+struct X3: prefix {};
+struct X4: prefix {};
+struct X5: prefix {};
+struct X6: prefix {};
+struct X7: prefix {};
+struct X8: prefix {};
+struct X9: prefix {};
+struct X10: prefix {};
+struct X11: prefix {};
+struct X12: prefix {};
+
+inline int get_value( prefix const& v )
+{
+    return v.v_;
+}
+
+#if !defined(NO_V2)
+
+template<class... T> int get_value( boost::variant2::variant<T...> const& v )
+{
+    return visit( []( prefix const& x ) { return x.v_; }, v );
+}
+
+#endif
+
+#if !defined(NO_BV)
+
+template<class... T> int get_value( boost::variant<T...> const& v )
+{
+    return boost::apply_visitor( []( prefix const& x ) { return x.v_; }, v );
+}
+
+#endif
+
+#if !defined(NO_SV)
+
+template<class... T> int get_value( std::variant<T...> const& v )
+{
+    return visit( []( prefix const& x ) { return x.v_; }, v );
+}
+
+#endif
+
+template<class V> void test_( int N )
+{
+    std::vector<V> w;
+    // lack of reserve is deliberate
+
+    auto tp1 = std::chrono::high_resolution_clock::now();
+
+    for( int i = 0; i < N / 12; ++i )
+    {
+        w.push_back( X1{ i } );
+        w.push_back( X2{ i } );
+        w.push_back( X3{ i } );
+        w.push_back( X4{ i } );
+        w.push_back( X5{ i } );
+        w.push_back( X6{ i } );
+        w.push_back( X7{ i } );
+        w.push_back( X8{ i } );
+        w.push_back( X9{ i } );
+        w.push_back( X10{ i } );
+        w.push_back( X11{ i } );
+        w.push_back( X12{ i } );
+    }
+
+    unsigned long long s = 0;
+
+    for( std::size_t i = 0, n = w.size(); i < n; ++i )
+    {
+        s = s + get_value( w[ i ] );
+    }
+
+    auto tp2 = std::chrono::high_resolution_clock::now();
+
+    std::cout << std::setw( 6 ) << std::chrono::duration_cast<std::chrono::milliseconds>( tp2 - tp1 ).count() << " ms; S=" << s << "\n";
+}
+
+template<class... T> void test( int N )
+{
+    std::cout << "N=" << N << ":\n";
+
+    std::cout << "        prefix: "; test_<prefix>( N );
+#if !defined(NO_V2)
+    std::cout << "      variant2: "; test_<boost::variant2::variant<T...>>( N );
+#endif
+#if !defined(NO_BV)
+    std::cout << "boost::variant: "; test_<boost::variant<T...>>( N );
+#endif
+#if !defined(NO_SV)
+    std::cout << "  std::variant: "; test_<std::variant<T...>>( N );
+#endif
+
+    std::cout << '\n';
+}
+
+int main()
+{
+    int const N = 100'000'000;
+
+    test<X1, X2, X3, X4, X5, X6, X7, X8, X9, X10, X11, X12>( N );
+}

benchmark/benchmark2.md

@@ -0,0 +1,207 @@
+# benchmark2.cpp results
+
+## VS 2017 15.9.7 64 bit (cl.exe 19.16, /EHsc /std:c++17)
+
+### /Od
+
+#### Compile time
+
+```
+      variant2 (-DONLY_V2): 1403 ms
+boost::variant (-DONLY_BV): 2972 ms
+  std::variant (-DONLY_SV): 1057 ms
+```
+
+#### Run time
+
+```
+N=100000000:
+        prefix:   7016 ms; S=416666583333336
+      variant2:  24723 ms; S=416666583333336
+boost::variant:  60438 ms; S=416666583333336
+  std::variant:  20707 ms; S=416666583333336
+```
+
+### /O2 /DNDEBUG
+
+#### Compile time
+
+```
+      variant2 (-DONLY_V2): 1778 ms
+boost::variant (-DONLY_BV): 3252 ms
+  std::variant (-DONLY_SV): 1372 ms
+```
+
+#### Run time
+
+```
+N=100000000:
+        prefix:    803 ms; S=416666583333336
+      variant2:   2124 ms; S=416666583333336
+boost::variant:   6191 ms; S=416666583333336
+  std::variant:   2193 ms; S=416666583333336
+```
+
+## g++ 7.4.0 -std=c++17 (Cygwin 64 bit)
+
+### -O0
+
+#### Compile time
+
+```
+      variant2 (-DONLY_V2): 1739 ms
+boost::variant (-DONLY_BV): 3113 ms
+  std::variant (-DONLY_SV): 1719 ms
+```
+
+#### Run time
+
+```
+N=100000000:
+        prefix:   5163 ms; S=416666583333336
+      variant2:  20628 ms; S=416666583333336
+boost::variant:  43308 ms; S=416666583333336
+  std::variant:  42375 ms; S=416666583333336
+```
+
+### -O1
+
+#### Compile time
+
+```
+      variant2 (-DONLY_V2): 1484 ms
+boost::variant (-DONLY_BV): 2947 ms
+  std::variant (-DONLY_SV): 1448 ms
+```
+
+#### Run time
+
+```
+N=100000000:
+        prefix:    781 ms; S=416666583333336
+      variant2:   1992 ms; S=416666583333336
+boost::variant:   2249 ms; S=416666583333336
+  std::variant:   4843 ms; S=416666583333336
+```
+
+### -O2 -DNDEBUG
+
+#### Compile time
+
+```
+      variant2 (-DONLY_V2): 1547 ms
+boost::variant (-DONLY_BV): 2999 ms
+  std::variant (-DONLY_SV): 1528 ms
+```
+
+#### Run time
+
+```
+N=100000000:
+        prefix:    793 ms; S=416666583333336
+      variant2:   1686 ms; S=416666583333336
+boost::variant:   1833 ms; S=416666583333336
+  std::variant:   4340 ms; S=416666583333336
+```
+
+### -O3 -DNDEBUG
+
+#### Compile time
+
+```
+      variant2 (-DONLY_V2): 1595 ms
+boost::variant (-DONLY_BV): 3084 ms
+  std::variant (-DONLY_SV): 1620 ms
+```
+
+#### Run time
+
+```
+N=100000000:
+        prefix:    853 ms; S=416666583333336
+      variant2:   1681 ms; S=416666583333336
+boost::variant:   1773 ms; S=416666583333336
+  std::variant:   3989 ms; S=416666583333336
+```
+
+## clang++ 5.0.1 -std=c++17 -stdlib=libc++ (Cygwin 64 bit)
+
+### -O0
+
+#### Compile time
+
+```
+      variant2 (-DONLY_V2): 1578 ms
+boost::variant (-DONLY_BV): 2623 ms
+  std::variant (-DONLY_SV): 1508 ms
+```
+
+#### Run time
+
+```
+N=100000000:
+        prefix:   4447 ms; S=416666583333336
+      variant2:  16016 ms; S=416666583333336
+boost::variant:  42365 ms; S=416666583333336
+  std::variant:  17817 ms; S=416666583333336
+```
+
+### -O1
+
+#### Compile time
+
+```
+      variant2 (-DONLY_V2): 1841 ms
+boost::variant (-DONLY_BV): 2919 ms
+  std::variant (-DONLY_SV): 1776 ms
+```
+
+#### Run time
+
+```
+N=100000000:
+        prefix:   1390 ms; S=416666583333336
+      variant2:   5397 ms; S=416666583333336
+boost::variant:  23234 ms; S=416666583333336
+  std::variant:   2807 ms; S=416666583333336
+```
+
+### -O2 -DNDEBUG
+
+#### Compile time
+
+```
+      variant2 (-DONLY_V2): 1766 ms
+boost::variant (-DONLY_BV): 2817 ms
+  std::variant (-DONLY_SV): 1718 ms
+```
+
+#### Run time
+
+```
+N=100000000:
+        prefix:    604 ms; S=416666583333336
+      variant2:   1625 ms; S=416666583333336
+boost::variant:   2735 ms; S=416666583333336
+  std::variant:   2664 ms; S=416666583333336
+```
+
+### -O3 -DNDEBUG
+
+#### Compile time
+
+```
+      variant2 (-DONLY_V2): 1720 ms
+boost::variant (-DONLY_BV): 2806 ms
+  std::variant (-DONLY_SV): 1737 ms
+```
+
+#### Run time
+
+```
+N=100000000:
+        prefix:    603 ms; S=416666583333336
+      variant2:   1608 ms; S=416666583333336
+boost::variant:   2696 ms; S=416666583333336
+  std::variant:   2668 ms; S=416666583333336
+```

doc/.gitignore

@@ -1,2 +1 @@
-/html/
 /pdf/

doc/Jamfile

@@ -6,14 +6,14 @@
 
 import asciidoctor ;
 
-html variant.html : variant.adoc ;
+html variant2.html : variant2.adoc ;
 
-install html_ : variant.html : <location>html ;
+install html_ : variant2.html : <location>html ;
 
-pdf variant.pdf : variant.adoc ;
-explicit variant.pdf ;
+pdf variant2.pdf : variant2.adoc ;
+explicit variant2.pdf ;
 
-install pdf_ : variant.pdf : <location>pdf ;
+install pdf_ : variant2.pdf : <location>pdf ;
 explicit pdf_ ;
 
 ###############################################################################

doc/variant2.adoc

@@ -16,8 +16,8 @@ Peter Dimov
 
 :leveloffset: +1
 
-include::variant/overview.adoc[]
-include::variant/reference.adoc[]
-include::variant/copyright.adoc[]
+include::variant2/overview.adoc[]
+include::variant2/reference.adoc[]
+include::variant2/copyright.adoc[]
 
 :leveloffset: -1

doc/variant2/reference.adoc

@@ -109,11 +109,12 @@ template<size_t I, class... T>
 template<size_t I, class... T>
   constexpr add_pointer_t<const variant_alternative_t<I, variant<T...>>>
     get_if(const variant<T...>* v) noexcept;
-template<class T, class... T>
-  constexpr add_pointer_t<T>
+
+template<class U, class... T>
+  constexpr add_pointer_t<U>
     get_if(variant<T...>* v) noexcept;
-template<class T, class... T>
-  constexpr add_pointer_t<const T>
+template<class U, class... T>
+  constexpr add_pointer_t<const U>
     get_if(const variant<T...>* v) noexcept;
 
 // relational operators
@@ -495,7 +496,7 @@ template<size_t I, class... A>
 [none]
 * {blank}
 +
-Requires: :: `I < sizeof(T...)`.
+Requires: :: `I < sizeof...(T)`.
 Effects:  ::
   Destroys the currently contained value, then initializes a new contained
   value as if using the expression `Ti(std::forward<A>(a)...)`.
@@ -513,7 +514,7 @@ template<size_t I, class V, class... A>
 [none]
 * {blank}
 +
-Requires: :: `I < sizeof(T...)`.
+Requires: :: `I < sizeof...(T)`.
 Effects:  ::
   Destroys the currently contained value, then initializes a new contained
   value as if using the expression `Ti(il, std::forward<A>(a)...)`.
@@ -745,16 +746,6 @@ template<size_t I, class... T>
   constexpr add_pointer_t<const variant_alternative_t<I, variant<T...>>>
     get_if(const variant<T...>* v) noexcept;
 ```
-```
-template<class T, class... T>
-  constexpr add_pointer_t<T>
-    get_if(variant<T...>* v) noexcept;
-```
-```
-template<class T, class... T>
-  constexpr add_pointer_t<const T>
-    get_if(const variant<T...>* v) noexcept;
-```
 [none]
 * {blank}
 +
@@ -762,6 +753,24 @@ Requires: :: `I < sizeof...(U)`. Otherwise, the program is ill-formed.
 Effects:  :: A pointer to the value stored in the variant, if
   `v != nullptr && v\->index() == I`. Otherwise, `nullptr`.
 
+```
+template<class U, class... T>
+  constexpr add_pointer_t<U>
+    get_if(variant<T...>* v) noexcept;
+```
+```
+template<class U, class... T>
+  constexpr add_pointer_t<const U>
+    get_if(const variant<T...>* v) noexcept;
+```
+[none]
+* {blank}
++
+Requires: :: The type `U` occurs exactly once in `T...`. Otherwise, the
+  program is ill-formed.
+Effects:  :: Equivalent to: `return get_if<I>(v);` with `I` being
+  the zero-based index of `U` in `T...`.
+
 ### Relational Operators
 
 ```

include/boost/variant2/outcome.hpp

@@ -1,259 +0,0 @@
-#ifndef BOOST_VARIANT2_OUTCOME_HPP_INCLUDED
-#define BOOST_VARIANT2_OUTCOME_HPP_INCLUDED
-
-//  Copyright 2017 Peter Dimov.
-//
-//  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
-
-#ifndef BOOST_VARIANT2_VARIANT_HPP_INCLUDED
-#include <boost/variant2/variant.hpp>
-#endif
-#include <system_error>
-#include <exception>
-#include <type_traits>
-#include <cassert>
-
-//
-
-namespace boost
-{
-namespace variant2
-{
-
-enum class outcome_errc
-{
-    not_initialized
-};
-
-class outcome_error_category: public std::error_category
-{
-public:
-
-    virtual const char * name() const noexcept
-    {
-        return "boost::variant2::outcome";
-    }
-
-    virtual std::string message( int e ) const
-    {
-        switch( e )
-        {
-        case (int)outcome_errc::not_initialized:
-
-            return "outcome<> not initialized";
-
-        default:
-
-            return "unknown outcome<> error";
-        }
-    }
-
-    static outcome_error_category const & instance()
-    {
-        static outcome_error_category cat;
-        return cat;
-    }
-};
-
-std::error_code make_error_code( outcome_errc e )
-{
-    return std::error_code( static_cast<int>( e ), outcome_error_category::instance() );
-}
-
-template<class T> class outcome
-{
-private:
-
-    variant<T, std::error_code, std::exception_ptr> v_;
-
-public:
-
-    // constructors
-
-    constexpr outcome() noexcept: v_( make_error_code( outcome_errc::not_initialized ) )
-    {
-    }
-
-    constexpr outcome( T const& t ): v_( t )
-    {
-    }
-
-    constexpr outcome( T&& t ): v_( std::move(t) )
-    {
-    }
-
-    constexpr outcome( std::error_code const & ec ) noexcept: v_( ec )
-    {
-    }
-
-    constexpr outcome( std::exception_ptr const & ep ) noexcept: v_( ep )
-    {
-    }
-
-    // queries
-
-    constexpr bool has_value() const noexcept
-    {
-        return v_.index() == 0;
-    }
-
-    constexpr bool has_error() const noexcept
-    {
-        return v_.index() == 1;
-    }
-
-    constexpr bool has_exception() const noexcept
-    {
-        return v_.index() == 2;
-    }
-
-    constexpr explicit operator bool() const noexcept
-    {
-        return v_.index() == 0;
-    }
-
-    // checked value access
-
-    constexpr T& value() &
-    {
-        if( has_value() )
-        {
-            return *get_if<0>(&v_);
-        }
-        else
-        {
-            throw std::system_error( *get_if<1>(&v_) );
-        }
-    }
-
-    constexpr T const& value() const&
-    {
-        if( has_value() )
-        {
-            return *get_if<0>(&v_);
-        }
-        else
-        {
-            throw std::system_error( *get_if<1>(&v_) );
-        }
-    }
-
-    constexpr T&& value() &&
-    {
-        return std::move( value() );
-    }
-
-    constexpr T const&& value() const&&
-    {
-        return std::move( value() );
-    }
-
-    // unchecked value access
-
-    T* operator->() noexcept
-    {
-        return get_if<0>(&v_);
-    }
-
-    T const* operator->() const noexcept
-    {
-        return get_if<0>(&v_);
-    }
-
-    T& operator*() & noexcept
-    {
-        T* p = get_if<0>(&v_);
-
-        assert( p != 0 );
-
-        return *p;
-    }
-
-    T const& operator*() const & noexcept
-    {
-        T const* p = get_if<0>(&v_);
-
-        assert( p != 0 );
-
-        return *p;
-    }
-
-    T&& operator*() && noexcept
-    {
-        return std::move(**this);
-    }
-
-    T const&& operator*() const && noexcept
-    {
-        return std::move(**this);
-    }
-
-    // error access
-
-    /*constexpr*/ std::error_code error() const noexcept
-    {
-        if( has_error() )
-        {
-            return *get_if<1>(&v_);
-        }
-        else
-        {
-            return std::error_code();
-        }
-    }
-
-    // exception access
-
-    std::exception_ptr exception() const noexcept
-    {
-        if( has_exception() )
-        {
-            return *get_if<2>(&v_);
-        }
-        else if( has_value() )
-        {
-            return std::exception_ptr();
-        }
-        else
-        {
-            return std::make_exception_ptr( std::system_error( *get_if<1>(&v_) ) );
-        }
-    }
-
-    // setters
-
-    void set_value( T const& t ) noexcept( std::is_nothrow_copy_constructible<T>::value )
-    {
-        v_.emplace<0>( t );
-    }
-
-    void set_value( T&& t ) noexcept( std::is_nothrow_move_constructible<T>::value )
-    {
-        v_.emplace<0>( std::move( t ) );
-    }
-
-    void set_error( std::error_code const & e ) noexcept
-    {
-        v_.emplace<1>( e );
-    }
-
-    void set_exception( std::exception_ptr const & x ) noexcept
-    {
-        v_.emplace<2>( x );
-    }
-
-    // swap
-
-    void swap( outcome& r ) noexcept( noexcept( v_.swap( r.v_ ) ) )
-    {
-        v_.swap( r.v_ );
-    }
-};
-
-} // namespace variant2
-} // namespace boost
-
-#endif // #ifndef BOOST_VARIANT2_OUTCOME_HPP_INCLUDED

include/boost/variant2/result.hpp

@@ -1,226 +0,0 @@
-#ifndef BOOST_VARIANT2_RESULT_HPP_INCLUDED
-#define BOOST_VARIANT2_RESULT_HPP_INCLUDED
-
-//  Copyright 2017 Peter Dimov.
-//
-//  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
-
-#ifndef BOOST_VARIANT2_VARIANT_HPP_INCLUDED
-#include <boost/variant2/variant.hpp>
-#endif
-#include <system_error>
-#include <type_traits>
-#include <cassert>
-
-//
-
-namespace boost
-{
-namespace variant2
-{
-
-enum class result_errc
-{
-    not_initialized
-};
-
-class result_error_category: public std::error_category
-{
-public:
-
-    virtual const char * name() const noexcept
-    {
-        return "boost::variant2::result";
-    }
-
-    virtual std::string message( int e ) const
-    {
-        switch( e )
-        {
-        case (int)result_errc::not_initialized:
-
-            return "result<> not initialized";
-
-        default:
-
-            return "unknown result<> error";
-        }
-    }
-
-    static result_error_category const & instance()
-    {
-        static result_error_category cat;
-        return cat;
-    }
-};
-
-std::error_code make_error_code( result_errc e )
-{
-    return std::error_code( static_cast<int>( e ), result_error_category::instance() );
-}
-
-template<class T> class result
-{
-private:
-
-    variant<T, std::error_code> v_;
-
-public:
-
-    // constructors
-
-    constexpr result() noexcept: v_( make_error_code( result_errc::not_initialized ) )
-    {
-    }
-
-    constexpr result( T const& t ): v_( t )
-    {
-    }
-
-    constexpr result( T&& t ): v_( std::move(t) )
-    {
-    }
-
-    constexpr result( std::error_code const & ec ) noexcept: v_( ec )
-    {
-    }
-
-    // queries
-
-    constexpr bool has_value() const noexcept
-    {
-        return v_.index() == 0;
-    }
-
-    constexpr bool has_error() const noexcept
-    {
-        return v_.index() == 1;
-    }
-
-    constexpr explicit operator bool() const noexcept
-    {
-        return v_.index() == 0;
-    }
-
-    // checked value access
-
-    constexpr T& value() &
-    {
-        if( has_value() )
-        {
-            return *get_if<0>(&v_);
-        }
-        else
-        {
-            throw std::system_error( *get_if<1>(&v_) );
-        }
-    }
-
-    constexpr T const& value() const&
-    {
-        if( has_value() )
-        {
-            return *get_if<0>(&v_);
-        }
-        else
-        {
-            throw std::system_error( *get_if<1>(&v_) );
-        }
-    }
-
-    constexpr T&& value() &&
-    {
-        return std::move( value() );
-    }
-
-    constexpr T const&& value() const&&
-    {
-        return std::move( value() );
-    }
-
-    // unchecked value access
-
-    T* operator->() noexcept
-    {
-        return get_if<0>(&v_);
-    }
-
-    T const* operator->() const noexcept
-    {
-        return get_if<0>(&v_);
-    }
-
-    T& operator*() & noexcept
-    {
-        T* p = get_if<0>(&v_);
-
-        assert( p != 0 );
-
-        return *p;
-    }
-
-    T const& operator*() const & noexcept
-    {
-        T const* p = get_if<0>(&v_);
-
-        assert( p != 0 );
-
-        return *p;
-    }
-
-    T&& operator*() && noexcept
-    {
-        return std::move(**this);
-    }
-
-    T const&& operator*() const && noexcept
-    {
-        return std::move(**this);
-    }
-
-    // error access
-
-    /*constexpr*/ std::error_code error() const noexcept
-    {
-        if( has_error() )
-        {
-            return *get_if<1>(&v_);
-        }
-        else
-        {
-            return std::error_code();
-        }
-    }
-
-    // setters
-
-    void set_value( T const& t ) noexcept( std::is_nothrow_copy_constructible<T>::value )
-    {
-        v_.emplace<0>( t );
-    }
-
-    void set_value( T&& t ) noexcept( std::is_nothrow_move_constructible<T>::value )
-    {
-        v_.emplace<0>( std::move( t ) );
-    }
-
-    void set_error( std::error_code const & e ) noexcept
-    {
-        v_.emplace<1>( e );
-    }
-
-    // swap
-
-    void swap( result& r ) noexcept( noexcept( v_.swap( r.v_ ) ) )
-    {
-        v_.swap( r.v_ );
-    }
-};
-
-} // namespace variant2
-} // namespace boost
-
-#endif // #ifndef BOOST_VARIANT2_RESULT_HPP_INCLUDED

include/boost/variant2/variant.hpp

@@ -1,7 +1,7 @@
 #ifndef BOOST_VARIANT2_VARIANT_HPP_INCLUDED
 #define BOOST_VARIANT2_VARIANT_HPP_INCLUDED
 
-// Copyright 2017, 2018 Peter Dimov.
+// Copyright 2017-2019 Peter Dimov.
 //
 // Distributed under the Boost Software License, Version 1.0.
 //
@@ -224,8 +224,16 @@ template<std::size_t I, class... T> struct variant_alternative<I, variant<T...>
 namespace detail
 {
 
+#if defined( BOOST_MP11_VERSION ) && BOOST_MP11_VERSION >= 107000
+
 template<class I, class T, class Q> using var_alt_impl = mp11::mp_invoke_q<Q, variant_alternative_t<I::value, T>>;
 
+#else
+
+template<class I, class T, class Q> using var_alt_impl = mp11::mp_invoke<Q, variant_alternative_t<I::value, T>>;
+
+#endif
+
 } // namespace detail
 
 template<std::size_t I, class T> struct variant_alternative
@@ -258,6 +266,10 @@ template<std::size_t I, class... T> struct variant_alternative<I, variant<T...>>
 
 #endif
 
+// variant_npos
+
+constexpr std::size_t variant_npos = ~static_cast<std::size_t>( 0 );
+
 // holds_alternative
 
 template<class U, class... T> constexpr bool holds_alternative( variant<T...> const& v ) noexcept
@@ -312,6 +324,37 @@ template<std::size_t I, class... T> constexpr variant_alternative_t<I, variant<T
 #endif
 }
 
+// detail::unsafe_get (for visit)
+
+namespace detail
+{
+
+template<std::size_t I, class... T> constexpr variant_alternative_t<I, variant<T...>>& unsafe_get(variant<T...>& v)
+{
+    static_assert( I < sizeof...(T), "Index out of bounds" );
+    return v._get_impl( mp11::mp_size_t<I>() );
+}
+
+template<std::size_t I, class... T> constexpr variant_alternative_t<I, variant<T...>>&& unsafe_get(variant<T...>&& v)
+{
+    static_assert( I < sizeof...(T), "Index out of bounds" );
+    return std::move( v._get_impl( mp11::mp_size_t<I>() ) );
+}
+
+template<std::size_t I, class... T> constexpr variant_alternative_t<I, variant<T...>> const& unsafe_get(variant<T...> const& v)
+{
+    static_assert( I < sizeof...(T), "Index out of bounds" );
+    return v._get_impl( mp11::mp_size_t<I>() );
+}
+
+template<std::size_t I, class... T> constexpr variant_alternative_t<I, variant<T...>> const&& unsafe_get(variant<T...> const&& v)
+{
+    static_assert( I < sizeof...(T), "Index out of bounds" );
+    return std::move( v._get_impl( mp11::mp_size_t<I>() ) );
+}
+
+} // namespace detail
+
 // get (type)
 
 template<class U, class... T> constexpr U& get(variant<T...>& v)
@@ -577,6 +620,13 @@ template<class... T> struct variant_base_impl<true, true, T...>
     {
     }
 
+    // requires: ix_ == 0
+    template<class I, class... A> void _replace( I, A&&... a )
+    {
+        ::new( &st1_ ) variant_storage<none, T...>( mp11::mp_size_t<I::value + 1>(), std::forward<A>(a)... );
+        ix_ = I::value + 1;
+    }
+
     constexpr std::size_t index() const noexcept
     {
         return ix_ - 1;
@@ -669,6 +719,13 @@ template<class... T> struct variant_base_impl<true, false, T...>
     {
     }
 
+    // requires: ix_ == 0
+    template<class I, class... A> void _replace( I, A&&... a )
+    {
+        ::new( &st1_ ) variant_storage<none, T...>( mp11::mp_size_t<I::value + 1>(), std::forward<A>(a)... );
+        ix_ = I::value + 1;
+    }
+
     constexpr std::size_t index() const noexcept
     {
         return ix_ >= 0? ix_ - 1: -ix_ - 1;
@@ -724,6 +781,13 @@ template<class... T> struct variant_base_impl<false, true, T...>
     {
     }
 
+    // requires: ix_ == 0
+    template<class I, class... A> void _replace( I, A&&... a )
+    {
+        ::new( &st1_ ) variant_storage<none, T...>( mp11::mp_size_t<I::value + 1>(), std::forward<A>(a)... );
+        ix_ = I::value + 1;
+    }
+
     //[&]( auto I ){
     //    using U = mp_at_c<mp_list<none, T...>, I>;
     //    st1_.get( I ).~U();
@@ -838,6 +902,13 @@ template<class... T> struct variant_base_impl<false, false, T...>
     {
     }
 
+    // requires: ix_ == 0
+    template<class I, class... A> void _replace( I, A&&... a )
+    {
+        ::new( &st1_ ) variant_storage<none, T...>( mp11::mp_size_t<I::value + 1>(), std::forward<A>(a)... );
+        ix_ = I::value + 1;
+    }
+
     //[&]( auto I ){
     //    using U = mp_at_c<mp_list<none, T...>, I>;
     //    st1_.get( I ).~U();
@@ -1059,7 +1130,7 @@ private:
 
         template<class I> void operator()( I i ) const
         {
-            ::new( static_cast<void*>( this_ ) ) variant_base( i, r._get_impl( i ) );
+            this_->_replace( i, r._get_impl( i ) );
         }
     };
 
@@ -1092,7 +1163,7 @@ private:
 
         template<class I> void operator()( I i ) const
         {
-            ::new( static_cast<void*>( this_ ) ) variant_base( i, std::move( r._get_impl( i ) ) );
+            this_->_replace( i, std::move( r._get_impl( i ) ) );
         }
     };
 
@@ -1142,7 +1213,7 @@ public:
 
     // assignment
     template<class E1 = void,
-        class E2 = mp11::mp_if<mp11::mp_all<std::is_trivially_destructible<T>..., detail::is_trivially_copy_assignable<T>...>, E1>
+        class E2 = mp11::mp_if<mp11::mp_all<std::is_trivially_destructible<T>..., detail::is_trivially_copy_constructible<T>..., detail::is_trivially_copy_assignable<T>...>, E1>
     >
     BOOST_CXX14_CONSTEXPR variant& operator=( variant const & r ) noexcept
     {
@@ -1173,7 +1244,7 @@ private:
 public:
 
     template<class E1 = void,
-        class E2 = mp11::mp_if<mp11::mp_not<mp11::mp_all<std::is_trivially_destructible<T>..., detail::is_trivially_copy_assignable<T>...>>, E1>,
+        class E2 = mp11::mp_if<mp11::mp_not<mp11::mp_all<std::is_trivially_destructible<T>..., detail::is_trivially_copy_constructible<T>..., detail::is_trivially_copy_assignable<T>...>>, E1>,
         class E3 = mp11::mp_if<mp11::mp_all<std::is_copy_constructible<T>..., std::is_copy_assignable<T>...>, E1>
     >
     BOOST_CXX14_CONSTEXPR variant& operator=( variant const & r )
@@ -1184,7 +1255,7 @@ public:
     }
 
     template<class E1 = void,
-        class E2 = mp11::mp_if<mp11::mp_all<std::is_trivially_destructible<T>..., detail::is_trivially_move_assignable<T>...>, E1>
+        class E2 = mp11::mp_if<mp11::mp_all<std::is_trivially_destructible<T>..., detail::is_trivially_move_constructible<T>..., detail::is_trivially_move_assignable<T>...>, E1>
     >
     BOOST_CXX14_CONSTEXPR variant& operator=( variant && r ) noexcept
     {
@@ -1215,7 +1286,7 @@ private:
 public:
 
     template<class E1 = void,
-        class E2 = mp11::mp_if<mp11::mp_not<mp11::mp_all<std::is_trivially_destructible<T>..., detail::is_trivially_move_assignable<T>...>>, E1>,
+        class E2 = mp11::mp_if<mp11::mp_not<mp11::mp_all<std::is_trivially_destructible<T>..., detail::is_trivially_move_constructible<T>..., detail::is_trivially_move_assignable<T>...>>, E1>,
         class E3 = mp11::mp_if<mp11::mp_all<std::is_move_constructible<T>..., std::is_move_assignable<T>...>, E1>
     >
     variant& operator=( variant && r )
@@ -1283,6 +1354,11 @@ public:
 
     // value status
 
+    constexpr bool valueless_by_exception() const noexcept
+    {
+        return false;
+    }
+
     using variant_base::index;
 
     // swap
@@ -1338,7 +1414,7 @@ private:
         template<class I> void operator()( I i ) const
         {
             using J = mp11::mp_find<mp11::mp_list<T...>, mp11::mp_at<mp11::mp_list<U...>, I>>;
-            ::new( static_cast<void*>(this_) ) variant_base( J{}, r._get_impl( i ) );
+            this_->_replace( J{}, r._get_impl( i ) );
         }
     };
 
@@ -1362,7 +1438,7 @@ private:
         template<class I> void operator()( I i ) const
         {
             using J = mp11::mp_find<mp11::mp_list<T...>, mp11::mp_at<mp11::mp_list<U...>, I>>;
-            ::new( static_cast<void*>(this_) ) variant_base( J{}, std::move( r._get_impl( i ) ) );
+            this_->_replace( J{}, std::move( r._get_impl( i ) ) );
         }
     };
 
@@ -1495,7 +1571,7 @@ template<class... T> struct eq_L
     variant<T...> const & v;
     variant<T...> const & w;
 
-    template<class I> bool operator()( I i ) const
+    template<class I> constexpr bool operator()( I i ) const
     {
         return v._get_impl( i ) == w._get_impl( i );
     }
@@ -1516,7 +1592,7 @@ template<class... T> struct ne_L
     variant<T...> const & v;
     variant<T...> const & w;
 
-    template<class I> bool operator()( I i ) const
+    template<class I> constexpr bool operator()( I i ) const
     {
         return v._get_impl( i ) != w._get_impl( i );
     }
@@ -1537,7 +1613,7 @@ template<class... T> struct lt_L
     variant<T...> const & v;
     variant<T...> const & w;
 
-    template<class I> bool operator()( I i ) const
+    template<class I> constexpr bool operator()( I i ) const
     {
         return v._get_impl( i ) < w._get_impl( i );
     }
@@ -1563,7 +1639,7 @@ template<class... T> struct le_L
     variant<T...> const & v;
     variant<T...> const & w;
 
-    template<class I> bool operator()( I i ) const
+    template<class I> constexpr bool operator()( I i ) const
     {
         return v._get_impl( i ) <= w._get_impl( i );
     }
@@ -1589,32 +1665,32 @@ template<class T> using remove_cv_ref_t = typename std::remove_cv<typename std::
 
 template<class T, class U> struct copy_cv_ref
 {
-	using type = T;
+    using type = T;
 };
 
 template<class T, class U> struct copy_cv_ref<T, U const>
 {
-	using type = T const;
+    using type = T const;
 };
 
 template<class T, class U> struct copy_cv_ref<T, U volatile>
 {
-	using type = T volatile;
+    using type = T volatile;
 };
 
 template<class T, class U> struct copy_cv_ref<T, U const volatile>
 {
-	using type = T const volatile;
+    using type = T const volatile;
 };
 
 template<class T, class U> struct copy_cv_ref<T, U&>
 {
-	using type = typename copy_cv_ref<T, U>::type&;
+    using type = typename copy_cv_ref<T, U>::type&;
 };
 
 template<class T, class U> struct copy_cv_ref<T, U&&>
 {
-	using type = typename copy_cv_ref<T, U>::type&&;
+    using type = typename copy_cv_ref<T, U>::type&&;
 };
 
 template<class T, class U> using copy_cv_ref_t = typename copy_cv_ref<T, U>::type;
@@ -1647,7 +1723,7 @@ template<class F, class V1> struct visit_L1
 
     template<class I> auto operator()( I ) const -> Vret<F, V1>
     {
-        return std::forward<F>(f)( get<I::value>( std::forward<V1>(v1) ) );
+        return std::forward<F>(f)( unsafe_get<I::value>( std::forward<V1>(v1) ) );
     }
 };
 
@@ -1688,7 +1764,7 @@ template<class F, class V1, class V2> struct visit_L2
 
     template<class I> auto operator()( I ) const -> Vret<F, V1, V2>
     {
-        auto f2 = bind_front( std::forward<F>(f), get<I::value>( std::forward<V1>(v1) ) );
+        auto f2 = bind_front( std::forward<F>(f), unsafe_get<I::value>( std::forward<V1>(v1) ) );
         return visit( f2, std::forward<V2>(v2) );
     }
 };
@@ -1713,7 +1789,7 @@ template<class F, class V1, class V2, class V3> struct visit_L3
 
     template<class I> auto operator()( I ) const -> Vret<F, V1, V2, V3>
     {
-        auto f2 = bind_front( std::forward<F>(f), get<I::value>( std::forward<V1>(v1) ) );
+        auto f2 = bind_front( std::forward<F>(f), unsafe_get<I::value>( std::forward<V1>(v1) ) );
         return visit( f2, std::forward<V2>(v2), std::forward<V3>(v3) );
     }
 };
@@ -1739,7 +1815,7 @@ template<class F, class V1, class V2, class V3, class V4> struct visit_L4
 
     template<class I> auto operator()( I ) const -> Vret<F, V1, V2, V3, V4>
     {
-        auto f2 = bind_front( std::forward<F>(f), get<I::value>( std::forward<V1>(v1) ) );
+        auto f2 = bind_front( std::forward<F>(f), unsafe_get<I::value>( std::forward<V1>(v1) ) );
         return visit( f2, std::forward<V2>(v2), std::forward<V3>(v3), std::forward<V4>(v4) );
     }
 };
@@ -1757,7 +1833,7 @@ template<class F, class V1, class V2, class... V> constexpr auto visit( F&& f, V
 {
     return mp11::mp_with_index<variant_size<V1>>( v1.index(), [&]( auto I ){
 
-        auto f2 = [&]( auto&&... a ){ return std::forward<F>(f)( get<I.value>( std::forward<V1>(v1) ), std::forward<decltype(a)>(a)... ); };
+        auto f2 = [&]( auto&&... a ){ return std::forward<F>(f)( detail::unsafe_get<I.value>( std::forward<V1>(v1) ), std::forward<decltype(a)>(a)... ); };
         return visit( f2, std::forward<V2>(v2), std::forward<V>(v)... );
 
     });

index.html

@@ -0,0 +1,15 @@
+<html>
+<head>
+<meta http-equiv="refresh" content="0; URL=doc/html/variant2.html">
+</head>
+<body>
+Automatic redirection failed, please go to
+<a href="doc/html/mp11.html">doc/html/variant2.html</a>.
+</body>
+</html>
+<!--
+  Copyright Beman Dawes, 2001
+  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
+-->

test/Jamfile

@@ -1,6 +1,6 @@
 #  Boost.Variant2 Library Test Jamfile
 #
-#  Copyright 2015-2017 Peter Dimov
+#  Copyright 2015-2019 Peter Dimov
 #
 #  Distributed under the Boost Software License, Version 1.0.
 #  See accompanying file LICENSE_1_0.txt or copy at
@@ -9,7 +9,19 @@
 import testing ;
 import ../../config/checks/config : requires ;
 
-project : requirements [ requires cxx11_variadic_templates cxx11_template_aliases cxx11_decltype cxx11_constexpr ] ;
+project
+  : default-build
+
+    <warnings>all
+
+  : requirements
+
+    [ requires cxx11_variadic_templates cxx11_template_aliases cxx11_decltype cxx11_constexpr ]
+
+    <toolset>msvc:<warnings-as-errors>on
+    <toolset>gcc:<warnings-as-errors>on
+    <toolset>clang:<warnings-as-errors>on
+  ;
 
 run variant_size.cpp ;
 run variant_alternative.cpp ;
@@ -57,10 +69,23 @@ run variant_emplace_type.cpp ;
 compile variant_emplace_type_cx.cpp : [ requires cxx14_constexpr ] ;
 
 run variant_swap.cpp ;
+
 run variant_eq_ne.cpp ;
+compile variant_eq_ne_cx.cpp : [ requires cxx14_constexpr ] ;
+
+run variant_lt_gt.cpp ;
+compile variant_lt_gt_cx.cpp : [ requires cxx14_constexpr ] ;
+
 run variant_destroy.cpp ;
 run variant_visit.cpp ;
-run variant_lt_gt.cpp ;
+
 run variant_convert_construct.cpp ;
 run variant_subset.cpp ;
 run variant_valueless.cpp ;
+
+run variant_copy_construct_throw.cpp ;
+run variant_move_construct_throw.cpp ;
+run variant_convert_construct_throw.cpp ;
+
+run variant_copy_assign_throw.cpp ;
+run variant_move_assign_throw.cpp ;

test/variant_convert_construct_throw.cpp

@@ -0,0 +1,95 @@
+
+// Copyright 2019 Peter Dimov
+//
+// 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
+
+#if defined(_MSC_VER)
+# pragma warning( disable: 4702 ) // unreachable code
+#endif
+
+#include <boost/variant2/variant.hpp>
+#include <boost/core/lightweight_test.hpp>
+#include <stdexcept>
+
+using namespace boost::variant2;
+
+struct X
+{
+    static int instances;
+
+    X()
+    {
+        ++instances;
+    }
+
+    X( X const& )
+    {
+        throw std::runtime_error( "X(X const&)" );
+    }
+
+    ~X()
+    {
+        --instances;
+    }
+};
+
+int X::instances = 0;
+
+void test_copy()
+{
+    X::instances = 0;
+
+    {
+        variant<X> v1;
+
+        BOOST_TEST_EQ( X::instances, 1 );
+
+        try
+        {
+            variant<X, int, float> v2( v1 );
+            BOOST_TEST_EQ( X::instances, 2 );
+        }
+        catch( std::exception const& )
+        {
+        }
+
+        BOOST_TEST_EQ( X::instances, 1 );
+    }
+
+    BOOST_TEST_EQ( X::instances, 0 );
+}
+
+void test_move()
+{
+    X::instances = 0;
+
+    {
+        variant<X> v1;
+
+        BOOST_TEST_EQ( X::instances, 1 );
+
+        try
+        {
+            variant<X, int, float> v2( std::move( v1 ) );
+            BOOST_TEST_EQ( X::instances, 2 );
+        }
+        catch( std::exception const& )
+        {
+        }
+
+        BOOST_TEST_EQ( X::instances, 1 );
+    }
+
+    BOOST_TEST_EQ( X::instances, 0 );
+}
+
+int main()
+{
+    test_copy();
+    test_move();
+
+    return boost::report_errors();
+}

test/variant_copy_assign_throw.cpp

@@ -0,0 +1,55 @@
+
+// Copyright 2019 Peter Dimov
+//
+// 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
+
+#if defined(_MSC_VER)
+# pragma warning( disable: 4702 ) // unreachable code
+#endif
+
+#include <boost/variant2/variant.hpp>
+#include <boost/core/lightweight_test.hpp>
+#include <stdexcept>
+
+using namespace boost::variant2;
+
+struct Y1
+{
+    Y1() noexcept {} // =default fails on msvc-14.0
+
+    Y1(Y1 const&)
+    {
+        throw std::runtime_error( "Y1(Y1 const&)" );
+    }
+
+    Y1& operator=(Y1 const&) = default;
+};
+
+struct Y2
+{
+    Y2() noexcept {}
+
+    Y2(Y2 const&)
+    {
+        throw std::runtime_error( "Y2(Y2 const&)" );
+    }
+
+    Y2& operator=(Y2 const&) = default;
+};
+
+void test()
+{
+    variant<Y1, Y2> v1( in_place_type_t<Y1>{} );
+    variant<Y1, Y2> v2( in_place_type_t<Y2>{} );
+
+    BOOST_TEST_THROWS( v1 = v2, std::runtime_error )
+}
+
+int main()
+{
+    test();
+    return boost::report_errors();
+}

test/variant_copy_construct.cpp

@@ -68,6 +68,16 @@ int main()
     test( variant<int, float>(1) );
     test( variant<int, float>(3.14f) );
 
+    test( variant<int const, float const>() );
+    test( variant<int const, float const>(1) );
+    test( variant<int const, float const>(3.14f) );
+
+    test( variant<std::string>() );
+    test( variant<std::string>("test") );
+
+    test( variant<std::string const>() );
+    test( variant<std::string const>("test") );
+
     test( variant<int, float, std::string>() );
     test( variant<int, float, std::string>(1) );
     test( variant<int, float, std::string>(3.14f) );
@@ -84,6 +94,8 @@ int main()
 
     test( variant<std::string, std::string, float>() );
 
+    test( variant<X1 const>() );
+
     test( variant<X1, X2>() );
     test( variant<X1, X2, int>() );
     test( variant<X1, X2, X2>() );

test/variant_copy_construct_throw.cpp

@@ -0,0 +1,69 @@
+
+// Copyright 2019 Peter Dimov
+//
+// 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
+
+#if defined(_MSC_VER)
+# pragma warning( disable: 4702 ) // unreachable code
+#endif
+
+#include <boost/variant2/variant.hpp>
+#include <boost/core/lightweight_test.hpp>
+#include <stdexcept>
+
+using namespace boost::variant2;
+
+struct X
+{
+    static int instances;
+
+    X()
+    {
+        ++instances;
+    }
+
+    X( X const& )
+    {
+        throw std::runtime_error( "X(X const&)" );
+    }
+
+    ~X()
+    {
+        --instances;
+    }
+};
+
+int X::instances = 0;
+
+void test()
+{
+    X::instances = 0;
+
+    {
+        variant<X> v1;
+
+        BOOST_TEST_EQ( X::instances, 1 );
+
+        try
+        {
+            variant<X> v2( v1 );
+            BOOST_TEST_EQ( X::instances, 2 );
+        }
+        catch( std::exception const& )
+        {
+        }
+
+        BOOST_TEST_EQ( X::instances, 1 );
+    }
+
+    BOOST_TEST_EQ( X::instances, 0 );
+}
+
+int main()
+{
+    test();
+    return boost::report_errors();
+}

test/variant_eq_ne_cx.cpp

@@ -0,0 +1,98 @@
+
+// Copyright 2017, 2019 Peter Dimov
+//
+// 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/variant2/variant.hpp>
+using namespace boost::variant2;
+
+#if !defined(BOOST_MP11_HAS_CXX14_CONSTEXPR)
+
+#include <boost/config/pragma_message.hpp>
+
+BOOST_PRAGMA_MESSAGE("Skipping constexpr op==, op!= test because BOOST_MP11_HAS_CXX14_CONSTEXPR is not defined")
+
+int main() {}
+
+#else
+
+struct X
+{
+};
+
+inline constexpr bool operator==( X const&, X const& ) { return false; }
+inline constexpr bool operator!=( X const&, X const& ) { return false; }
+
+#define STATIC_ASSERT(...) static_assert(__VA_ARGS__, #__VA_ARGS__)
+
+int main()
+{
+    {
+        constexpr variant<int> v1, v2, v3( 1 ), v4( 1 );
+
+        STATIC_ASSERT( v1 == v2 );
+        STATIC_ASSERT( !(v1 != v2) );
+
+        STATIC_ASSERT( v1 != v3 );
+        STATIC_ASSERT( !(v1 == v3) );
+
+        STATIC_ASSERT( v3 == v4 );
+        STATIC_ASSERT( !(v3 != v4) );
+    }
+
+    {
+        constexpr variant<int, float> v1, v2, v3( 1 ), v4( 1 ), v5( 3.14f ), v6( 3.14f );
+
+        STATIC_ASSERT( v1 == v2 );
+        STATIC_ASSERT( !(v1 != v2) );
+
+        STATIC_ASSERT( v1 != v3 );
+        STATIC_ASSERT( !(v1 == v3) );
+
+        STATIC_ASSERT( v3 == v4 );
+        STATIC_ASSERT( !(v3 != v4) );
+
+        STATIC_ASSERT( v1 != v5 );
+        STATIC_ASSERT( !(v1 == v5) );
+
+        STATIC_ASSERT( v3 != v5 );
+        STATIC_ASSERT( !(v3 == v5) );
+
+        STATIC_ASSERT( v5 == v6 );
+        STATIC_ASSERT( !(v5 != v6) );
+    }
+
+    {
+        constexpr variant<int, int, float> v1, v2, v3( in_place_index_t<1>{} ), v4( in_place_index_t<1>{} ), v5( 3.14f ), v6( 3.14f );
+
+        STATIC_ASSERT( v1 == v2 );
+        STATIC_ASSERT( !(v1 != v2) );
+
+        STATIC_ASSERT( v1 != v3 );
+        STATIC_ASSERT( !(v1 == v3) );
+
+        STATIC_ASSERT( v3 == v4 );
+        STATIC_ASSERT( !(v3 != v4) );
+
+        STATIC_ASSERT( v1 != v5 );
+        STATIC_ASSERT( !(v1 == v5) );
+
+        STATIC_ASSERT( v3 != v5 );
+        STATIC_ASSERT( !(v3 == v5) );
+
+        STATIC_ASSERT( v5 == v6 );
+        STATIC_ASSERT( !(v5 != v6) );
+    }
+
+    {
+        constexpr variant<X> v1, v2;
+
+        STATIC_ASSERT( !(v1 == v2) );
+        STATIC_ASSERT( !(v1 != v2) );
+    }
+}
+
+#endif

test/variant_lt_gt_cx.cpp

@@ -0,0 +1,91 @@
+
+// Copyright 2017, 2019 Peter Dimov
+//
+// 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/variant2/variant.hpp>
+using namespace boost::variant2;
+
+#if !defined(BOOST_MP11_HAS_CXX14_CONSTEXPR)
+
+#include <boost/config/pragma_message.hpp>
+
+BOOST_PRAGMA_MESSAGE("Skipping constexpr op<, op<= test because BOOST_MP11_HAS_CXX14_CONSTEXPR is not defined")
+
+int main() {}
+
+#else
+
+struct X
+{
+};
+
+inline constexpr bool operator<( X const&, X const& ) { return false; }
+inline constexpr bool operator>( X const&, X const& ) { return false; }
+inline constexpr bool operator<=( X const&, X const& ) { return false; }
+inline constexpr bool operator>=( X const&, X const& ) { return false; }
+
+#define STATIC_ASSERT(...) static_assert(__VA_ARGS__, #__VA_ARGS__)
+
+#define TEST_EQ( v1, v2 ) \
+    STATIC_ASSERT( !(v1 < v2) ); \
+    STATIC_ASSERT( !(v1 > v2) ); \
+    STATIC_ASSERT( v1 <= v2 ); \
+    STATIC_ASSERT( v1 >= v2 );
+
+#define TEST_LE( v1, v3 ) \
+    STATIC_ASSERT( v1 < v3 ); \
+    STATIC_ASSERT( v3 > v1 ); \
+    STATIC_ASSERT( !(v1 > v3) ); \
+    STATIC_ASSERT( !(v3 < v1) ); \
+    STATIC_ASSERT( v1 <= v3 ); \
+    STATIC_ASSERT( v3 >= v1 ); \
+    STATIC_ASSERT( !(v1 >= v3) ); \
+    STATIC_ASSERT( !(v3 <= v1) );
+
+int main()
+{
+    {
+        constexpr variant<int> v1, v2, v3( 1 ), v4( 1 );
+
+        TEST_EQ( v1, v2 )
+        TEST_LE( v1, v3 )
+        TEST_EQ( v3, v4 )
+    }
+
+    {
+        constexpr variant<int, float> v1, v2, v3( 1 ), v4( 1 ), v5( 3.14f ), v6( 3.14f );
+
+        TEST_EQ( v1, v2 )
+        TEST_LE( v1, v3 )
+        TEST_EQ( v3, v4 )
+        TEST_LE( v1, v5 )
+        TEST_LE( v3, v5 )
+        TEST_EQ( v5, v6 )
+    }
+
+    {
+        constexpr variant<int, int, float> v1, v2, v3( in_place_index_t<1>{} ), v4( in_place_index_t<1>{} ), v5( 3.14f ), v6( 3.14f );
+
+        TEST_EQ( v1, v2 )
+        TEST_LE( v1, v3 )
+        TEST_EQ( v3, v4 )
+        TEST_LE( v1, v5 )
+        TEST_LE( v3, v5 )
+        TEST_EQ( v5, v6 )
+    }
+
+    {
+        constexpr variant<X> v1, v2;
+
+        STATIC_ASSERT( !(v1 < v2) );
+        STATIC_ASSERT( !(v1 > v2) );
+        STATIC_ASSERT( !(v1 <= v2) );
+        STATIC_ASSERT( !(v1 >= v2) );
+    }
+}
+
+#endif

test/variant_move_assign_throw.cpp

@@ -0,0 +1,55 @@
+
+// Copyright 2019 Peter Dimov
+//
+// 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
+
+#if defined(_MSC_VER)
+# pragma warning( disable: 4702 ) // unreachable code
+#endif
+
+#include <boost/variant2/variant.hpp>
+#include <boost/core/lightweight_test.hpp>
+#include <stdexcept>
+
+using namespace boost::variant2;
+
+struct Y1
+{
+    Y1() noexcept {} // =default fails on msvc-14.0
+
+    Y1(Y1&&)
+    {
+        throw std::runtime_error( "Y1(Y1&&)" );
+    }
+
+    Y1& operator=(Y1&&) = default;
+};
+
+struct Y2
+{
+    Y2() noexcept {}
+
+    Y2(Y2&&)
+    {
+        throw std::runtime_error( "Y2(Y2&&)" );
+    }
+
+    Y2& operator=(Y2&&) = default;
+};
+
+void test()
+{
+    variant<Y1, Y2> v1( in_place_type_t<Y1>{} );
+    variant<Y1, Y2> v2( in_place_type_t<Y2>{} );
+
+    BOOST_TEST_THROWS( v1 = std::move( v2 ), std::runtime_error )
+}
+
+int main()
+{
+    test();
+    return boost::report_errors();
+}

test/variant_move_construct.cpp

@@ -69,6 +69,16 @@ int main()
     test( variant<int, float>(1) );
     test( variant<int, float>(3.14f) );
 
+    test( variant<int const, float const>() );
+    test( variant<int const, float const>(1) );
+    test( variant<int const, float const>(3.14f) );
+
+    test( variant<std::string>() );
+    test( variant<std::string>("test") );
+
+    test( variant<std::string const>() );
+    test( variant<std::string const>("test") );
+
     test( variant<int, float, std::string>() );
     test( variant<int, float, std::string>(1) );
     test( variant<int, float, std::string>(3.14f) );
@@ -85,6 +95,8 @@ int main()
 
     test( variant<std::string, std::string, float>() );
 
+    test( variant<X1 const>() );
+
     test( variant<X1, X2>() );
     test( variant<X1, X2, int>() );
     test( variant<X1, X2, X2>() );

test/variant_move_construct_throw.cpp

@@ -0,0 +1,69 @@
+
+// Copyright 2019 Peter Dimov
+//
+// 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
+
+#if defined(_MSC_VER)
+# pragma warning( disable: 4702 ) // unreachable code
+#endif
+
+#include <boost/variant2/variant.hpp>
+#include <boost/core/lightweight_test.hpp>
+#include <stdexcept>
+
+using namespace boost::variant2;
+
+struct X
+{
+    static int instances;
+
+    X()
+    {
+        ++instances;
+    }
+
+    X( X const& )
+    {
+        throw std::runtime_error( "X(X const&)" );
+    }
+
+    ~X()
+    {
+        --instances;
+    }
+};
+
+int X::instances = 0;
+
+void test()
+{
+    X::instances = 0;
+
+    {
+        variant<X> v1;
+
+        BOOST_TEST_EQ( X::instances, 1 );
+
+        try
+        {
+            variant<X> v2( std::move( v1 ) );
+            BOOST_TEST_EQ( X::instances, 2 );
+        }
+        catch( std::exception const& )
+        {
+        }
+
+        BOOST_TEST_EQ( X::instances, 1 );
+    }
+
+    BOOST_TEST_EQ( X::instances, 0 );
+}
+
+int main()
+{
+    test();
+    return boost::report_errors();
+}

test/variant_subset.cpp

@@ -6,6 +6,10 @@
 // See accompanying file LICENSE_1_0.txt or copy at
 // http://www.boost.org/LICENSE_1_0.txt
 
+#if defined(_MSC_VER)
+# pragma warning( disable: 4702 ) // unreachable code
+#endif
+
 #include <boost/variant2/variant.hpp>
 #include <boost/core/lightweight_test.hpp>
 #include <boost/core/lightweight_test_trait.hpp>

test/variant_valueless.cpp

@@ -6,6 +6,10 @@
 // See accompanying file LICENSE_1_0.txt or copy at
 // http://www.boost.org/LICENSE_1_0.txt
 
+#if defined(_MSC_VER)
+# pragma warning( disable: 4702 ) // unreachable code
+#endif
+
 #include <boost/variant2/variant.hpp>
 #include <boost/core/lightweight_test.hpp>
 #include <type_traits>