Use BOOST_INLINE_CONSTEXPR for placeholders if inline variables are supported

include/boost/bind/placeholders.hpp

@@ -41,6 +41,18 @@ inline boost::arg<7> _7() { return boost::arg<7>(); }
 inline boost::arg<8> _8() { return boost::arg<8>(); }
 inline boost::arg<9> _9() { return boost::arg<9>(); }
 
+#elif !defined(BOOST_NO_CXX17_INLINE_VARIABLES)
+
+BOOST_INLINE_CONSTEXPR boost::arg<1> _1;
+BOOST_INLINE_CONSTEXPR boost::arg<2> _2;
+BOOST_INLINE_CONSTEXPR boost::arg<3> _3;
+BOOST_INLINE_CONSTEXPR boost::arg<4> _4;
+BOOST_INLINE_CONSTEXPR boost::arg<5> _5;
+BOOST_INLINE_CONSTEXPR boost::arg<6> _6;
+BOOST_INLINE_CONSTEXPR boost::arg<7> _7;
+BOOST_INLINE_CONSTEXPR boost::arg<8> _8;
+BOOST_INLINE_CONSTEXPR boost::arg<9> _9;
+
 #else
 
 BOOST_STATIC_CONSTEXPR boost::arg<1> _1;

include/boost/bind/protect.hpp

@@ -2,10 +2,10 @@
 #define BOOST_BIND_PROTECT_HPP_INCLUDED
 
 //
-//  protect.hpp
+// protect.hpp
 //
-//  Copyright (c) 2002 Peter Dimov and Multi Media Ltd.
-//  Copyright (c) 2009 Steven Watanabe
+// Copyright 2002, 2020 Peter Dimov
+// Copyright 2009 Steven Watanabe
 //
 // Distributed under the Boost Software License, Version 1.0. (See
 // accompanying file LICENSE_1_0.txt or copy at
@@ -13,7 +13,8 @@
 //
 
 #include <boost/config.hpp>
-#include <boost/detail/workaround.hpp>
+#include <boost/config/workaround.hpp>
+#include <utility>
 
 namespace boost
 {
@@ -21,8 +22,53 @@ namespace boost
 namespace _bi
 {
 
+#if !defined(BOOST_NO_CXX11_VARIADIC_TEMPLATES) && !defined(BOOST_NO_CXX11_RVALUE_REFERENCES) && !defined(BOOST_NO_CXX11_DECLTYPE)
+
+template<class T> struct protect_make_void
+{
+    typedef void type;
+};
+
+template<class F, class E = void> struct protect_result_type
+{
+};
+
+template<class F> struct protect_result_type< F, typename protect_make_void<typename F::result_type>::type >
+{
+    typedef typename F::result_type result_type;
+};
+
+template<class F> class protected_bind_t: public protect_result_type<F>
+{
+private:
+
+    F f_;
+
+public:
+
+    explicit protected_bind_t( F f ): f_( f )
+    {
+    }
+
+    template<class... A> auto operator()( A&&... a ) -> decltype( f_( std::forward<A>(a)... ) )
+    {
+        return f_( std::forward<A>(a)... );
+    }
+
+    template<class... A> auto operator()( A&&... a ) const -> decltype( f_( std::forward<A>(a)... ) )
+    {
+        return f_( std::forward<A>(a)... );
+    }
+};
+
+#else
+
 template<class F> class protected_bind_t
 {
+private:
+
+    F f_;
+
 public:
 
     typedef typename F::result_type result_type;
@@ -286,12 +332,10 @@ public:
     }
 
 #endif
-
-private:
-
-    F f_;
 };
 
+#endif
+
 } // namespace _bi
 
 template<class F> _bi::protected_bind_t<F> protect(F f)

test/Jamfile.v2

@@ -75,3 +75,5 @@ run bind_noexcept_mf_test.cpp ;
 run global_placeholders.cpp ;
 run mem_fn_noexcept_test.cpp ;
 run bind_cpp20_test.cpp ;
+run protect_test2.cpp ;
+run protect_cpp20_test.cpp ;

test/protect_cpp20_test.cpp

@@ -0,0 +1,42 @@
+// Copyright 2020 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt)
+
+#include <boost/bind/protect.hpp>
+#include <boost/core/lightweight_test.hpp>
+#include <boost/config.hpp>
+#include <boost/config/workaround.hpp>
+#include <functional>
+
+//
+
+int main()
+{
+    BOOST_TEST_EQ( boost::protect( std::plus<int>() )( 1, 2 ), 3 );
+    BOOST_TEST_EQ( boost::protect( std::minus<int>() )( 1, 2 ), -1 );
+    BOOST_TEST_EQ( boost::protect( std::multiplies<int>() )( 1, 2 ), 2 );
+    BOOST_TEST_EQ( boost::protect( std::divides<int>() )( 1, 2 ), 0 );
+    BOOST_TEST_EQ( boost::protect( std::modulus<int>() )( 1, 2 ), 1 );
+    BOOST_TEST_EQ( boost::protect( std::negate<int>() )( 1 ), -1 );
+
+    BOOST_TEST_EQ( boost::protect( std::equal_to<int>() )( 1, 2 ), false );
+    BOOST_TEST_EQ( boost::protect( std::not_equal_to<int>() )( 1, 2 ), true );
+    BOOST_TEST_EQ( boost::protect( std::greater<int>() )( 1, 2 ), false );
+    BOOST_TEST_EQ( boost::protect( std::less<int>() )( 1, 2 ), true );
+    BOOST_TEST_EQ( boost::protect( std::greater_equal<int>() )( 1, 2 ), false );
+    BOOST_TEST_EQ( boost::protect( std::less_equal<int>() )( 1, 2 ), true );
+
+    BOOST_TEST_EQ( boost::protect( std::logical_and<int>() )( 1, 2 ), true );
+    BOOST_TEST_EQ( boost::protect( std::logical_or<int>() )( 1, 2 ), true );
+    BOOST_TEST_EQ( boost::protect( std::logical_not<int>() )( 1 ), false );
+
+#if !BOOST_WORKAROUND(BOOST_MSVC, < 1600)
+
+    BOOST_TEST_EQ( boost::protect( std::bit_and<int>() )( 1, 2 ), 0 );
+    BOOST_TEST_EQ( boost::protect( std::bit_or<int>() )( 1, 2 ), 3 );
+    BOOST_TEST_EQ( boost::protect( std::bit_xor<int>() )( 1, 2 ), 3 );
+
+#endif
+
+    return boost::report_errors();
+}

test/protect_test2.cpp

@@ -0,0 +1,46 @@
+// protect_test2.cpp
+//
+// Copyright 2020 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/bind/protect.hpp>
+#include <boost/core/lightweight_test_trait.hpp>
+#include <boost/core/is_same.hpp>
+
+template<class T, class F> void test( F )
+{
+    BOOST_TEST_TRAIT_TRUE((boost::core::is_same<typename T::result_type, typename F::result_type>));
+}
+
+struct X
+{
+    struct result_type {};
+};
+
+struct Y
+{
+};
+
+template<class T, class U> struct inherit: T, U
+{
+};
+
+template<class F> void test2( F )
+{
+    // test that F doesn't have ::result_type
+    BOOST_TEST_TRAIT_TRUE((boost::core::is_same<typename inherit<F, X>::result_type, typename X::result_type>));
+}
+
+int main()
+{
+    test<X>( boost::protect( X() ) );
+
+#if !defined(BOOST_NO_CXX11_VARIADIC_TEMPLATES) && !defined(BOOST_NO_CXX11_RVALUE_REFERENCES) && !defined(BOOST_NO_CXX11_DECLTYPE)
+
+    test2( boost::protect( Y() ) );
+
+#endif
+
+    return boost::report_errors();
+}