From e97bcb4c566fe6e22db64059d56b79e1162be8fa Mon Sep 17 00:00:00 2001
From: Emil Dotchevski <emil@revergestudios.com>
Date: Sat, 31 Aug 2013 23:24:40 +0000
Subject: [PATCH] N3757

[SVN r85538]
---
 include/boost/exception/N3757.hpp     | 46 ++++++++++++++++++
 include/boost/exception/exception.hpp |  6 +++
 test/Jamfile.v2                       |  3 +-
 test/N3757_test.cpp                   | 67 +++++++++++++++++++++++++++
 4 files changed, 121 insertions(+), 1 deletion(-)
 create mode 100644 include/boost/exception/N3757.hpp
 create mode 100644 test/N3757_test.cpp

diff --git a/include/boost/exception/N3757.hpp b/include/boost/exception/N3757.hpp
new file mode 100644
index 0000000..23b0606
--- /dev/null
+++ b/include/boost/exception/N3757.hpp
@@ -0,0 +1,46 @@
+//Copyright (c) 2006-2013 Emil Dotchevski and Reverge Studios, Inc.
+
+//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 UUID_9011016A11A711E3B46CD9FA6088709B
+#define UUID_9011016A11A711E3B46CD9FA6088709B
+#if (__GNUC__*100+__GNUC_MINOR__>301) && !defined(BOOST_EXCEPTION_ENABLE_WARNINGS)
+#pragma GCC system_header
+#endif
+#if defined(_MSC_VER) && !defined(BOOST_EXCEPTION_ENABLE_WARNINGS)
+#pragma warning(push,1)
+#endif
+
+#include <boost/exception/info.hpp>
+#include <boost/exception/get_error_info.hpp>
+
+namespace
+boost
+    {
+    //Here we're using the boost::error_info machinery to store the info in the exception
+    //object. Within the context of N3757, this is strictly an implementation detail.
+
+    template <class Tag>
+    inline
+    void
+    exception::
+    set( typename Tag::type const & v )
+        {
+        exception_detail::set_info(*this,error_info<Tag,typename Tag::type>(v));
+        }
+
+    template <class Tag>
+    inline
+    typename Tag::type const *
+    exception::
+    get() const
+        {
+        return get_error_info<error_info<Tag,typename Tag::type> >(*this);
+        }
+    }
+
+#if defined(_MSC_VER) && !defined(BOOST_EXCEPTION_ENABLE_WARNINGS)
+#pragma warning(pop)
+#endif
+#endif
diff --git a/include/boost/exception/exception.hpp b/include/boost/exception/exception.hpp
index 31d4317..d762cf8 100644
--- a/include/boost/exception/exception.hpp
+++ b/include/boost/exception/exception.hpp
@@ -207,6 +207,12 @@ boost
     class
     exception
         {
+        //<N3757>
+        public:
+        template <class Tag> void set( typename Tag::type const & );
+        template <class Tag> typename Tag::type const * get() const;
+        //</N3757>
+
         protected:
 
         exception():
diff --git a/test/Jamfile.v2 b/test/Jamfile.v2
index 6195a70..d2dfcd6 100644
--- a/test/Jamfile.v2
+++ b/test/Jamfile.v2
@@ -1,6 +1,6 @@
 # Boost Exception Library test Jamfile
 #
-# Copyright (c) 2006-2009 Emil Dotchevski and Reverge Studios, Inc.
+# Copyright (c) 2006-2013 Emil Dotchevski and Reverge Studios, Inc.
 #
 # 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)
@@ -42,6 +42,7 @@ run no_exceptions_test.cpp : : : <exception-handling>off ;
 run errinfos_test.cpp ;
 run exception_ptr_test.cpp/<define>BOOST_ENABLE_NON_INTRUSIVE_EXCEPTION_PTR ../../thread/src/tss_null.cpp /boost/exception /boost//thread : : : <threading>multi : non_intrusive_exception_ptr_test ;
 run exception_ptr_test.cpp ../../thread/src/tss_null.cpp /boost//thread : : : <threading>multi ;
+run N3757_test.cpp ;
 
 compile-fail exception_fail.cpp ;
 compile-fail throw_exception_fail.cpp ;
diff --git a/test/N3757_test.cpp b/test/N3757_test.cpp
new file mode 100644
index 0000000..caa93ba
--- /dev/null
+++ b/test/N3757_test.cpp
@@ -0,0 +1,67 @@
+//Copyright (c) 2006-2013 Emil Dotchevski and Reverge Studios, Inc.
+
+//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)
+
+//This file tests the N3757 syntax for adding error info to std::exception, which is
+//different from the syntax used by Boost Exception.
+
+#include <boost/exception/N3757.hpp>
+#include <boost/exception/diagnostic_information.hpp>
+#include <boost/detail/lightweight_test.hpp>
+#include <ostream>
+
+struct tag1 { typedef int type; };
+struct tag2 { typedef std::string type; };
+struct tag3 { typedef int type; };
+
+struct my_error_code { int ec; my_error_code(int ec):ec(ec){ } };
+struct tag_error_code { typedef my_error_code type; };
+
+bool my_error_code_to_string_called=false;
+
+std::ostream &
+operator<<( std::ostream & s, my_error_code const & x )
+{
+    my_error_code_to_string_called=true;
+    return s << "my_error_code(" << x.ec << ')';
+}
+
+struct my_exception: virtual std::exception, virtual boost::exception { };
+
+int
+main()
+    {
+    try
+        {
+        throw my_exception();
+        }
+    catch(
+	boost::exception & e )
+        {
+        e.set<tag1>(42);
+        e.set<tag2>("42");
+        e.set<tag_error_code>(42); //Implicit conversion
+        try
+            {
+            throw;
+            }
+        catch(
+        my_exception & e )
+            {
+            BOOST_TEST(e.get<tag1>() && *e.get<tag1>()==42);
+            BOOST_TEST(e.get<tag2>() && *e.get<tag2>()=="42");
+            BOOST_TEST(!e.get<tag3>());
+            BOOST_TEST(e.get<tag_error_code>() && e.get<tag_error_code>()->ec==42);
+
+            //Below we're verifying that an error code wrapped in a user-defined type
+            //invokes the correct op<< to convert the error code to string.
+            //Note that N3757 diagnostic_information uses different syntax, it is a
+            //member of of std::exception.
+            std::string di=boost::diagnostic_information(e);
+            BOOST_TEST(!di.empty());
+            BOOST_TEST(my_error_code_to_string_called);
+            }
+        }
+    return boost::report_errors();
+    }