Add deduction guides to shared_ptr and weak_ptr. Fixes #73.

include/boost/smart_ptr/shared_ptr.hpp

@@ -1175,6 +1175,13 @@ template<class D, class T> D const * basic_get_local_deleter( D const *, shared_
 
 } // namespace detail
 
+#if defined(__cpp_deduction_guides)
+
+template<class T> shared_ptr( weak_ptr<T> ) -> shared_ptr<T>;
+template<class T, class D> shared_ptr( std::unique_ptr<T, D> ) -> shared_ptr<T>;
+
+#endif
+
 } // namespace boost
 
 #if defined( BOOST_SP_DISABLE_DEPRECATED )

include/boost/smart_ptr/weak_ptr.hpp

@@ -264,6 +264,12 @@ template<class T> void swap(weak_ptr<T> & a, weak_ptr<T> & b) BOOST_SP_NOEXCEPT
     a.swap(b);
 }
 
+#if defined(__cpp_deduction_guides)
+
+template<class T> weak_ptr( shared_ptr<T> ) -> weak_ptr<T>;
+
+#endif
+
 } // namespace boost
 
 #endif  // #ifndef BOOST_SMART_PTR_WEAK_PTR_HPP_INCLUDED

test/Jamfile

@@ -352,3 +352,7 @@ run allocate_unique_noinit_test.cpp ;
 run allocate_unique_test.cpp ;
 run allocate_unique_throws_test.cpp ;
 run allocate_unique_value_test.cpp ;
+
+run sp_guides_test.cpp ;
+run sp_guides_test2.cpp ;
+run wp_guides_test.cpp ;

test/sp_guides_test.cpp

@@ -0,0 +1,25 @@
+// Copyright 2020 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#if defined(__cpp_deduction_guides)
+
+#include <boost/shared_ptr.hpp>
+#include <boost/weak_ptr.hpp>
+
+int main()
+{
+    boost::shared_ptr<int> p1( new int );
+    boost::weak_ptr<int> p2( p1 );
+    boost::shared_ptr p3( p2 );
+}
+
+#else
+
+#include <boost/config/pragma_message.hpp>
+
+BOOST_PRAGMA_MESSAGE( "Skipping test because __cpp_deduction_guides is not defined" )
+
+int main() {}
+
+#endif

test/sp_guides_test2.cpp

@@ -0,0 +1,23 @@
+// Copyright 2020 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#if defined(__cpp_deduction_guides)
+
+#include <boost/shared_ptr.hpp>
+#include <memory>
+
+int main()
+{
+    boost::shared_ptr p2( std::unique_ptr<int>( new int ) );
+}
+
+#else
+
+#include <boost/config/pragma_message.hpp>
+
+BOOST_PRAGMA_MESSAGE( "Skipping test because __cpp_deduction_guides is not defined" )
+
+int main() {}
+
+#endif

test/wp_guides_test.cpp

@@ -0,0 +1,24 @@
+// Copyright 2020 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#if defined(__cpp_deduction_guides)
+
+#include <boost/shared_ptr.hpp>
+#include <boost/weak_ptr.hpp>
+
+int main()
+{
+    boost::shared_ptr<int> p1( new int );
+    boost::weak_ptr p2( p1 );
+}
+
+#else
+
+#include <boost/config/pragma_message.hpp>
+
+BOOST_PRAGMA_MESSAGE( "Skipping test because __cpp_deduction_guides is not defined" )
+
+int main() {}
+
+#endif