From 87c427b5dfdcf8c84a81d07e454bf78b431489ee Mon Sep 17 00:00:00 2001
From: Peter Dimov <pdimov@pdimov.com>
Date: Thu, 22 Jun 2017 19:27:55 +0300
Subject: [PATCH] Rework the equivalence logic in terms of the corresponding
 downstream `equivalent`

---
 include/boost/system/error_code.hpp | 37 ++++++++++++++++++++---------
 1 file changed, 26 insertions(+), 11 deletions(-)

diff --git a/include/boost/system/error_code.hpp b/include/boost/system/error_code.hpp
index dd585d7..5d98301 100644
--- a/include/boost/system/error_code.hpp
+++ b/include/boost/system/error_code.hpp
@@ -618,45 +618,60 @@ namespace boost
     inline bool error_category::std_category::equivalent( int code,
       const std::error_condition & condition ) const BOOST_NOEXCEPT
     {
-      if( default_error_condition( code ) == condition )
+      if( condition.category() == *this )
       {
-        return true;
+        boost::system::error_condition bn( condition.value(), *pc_ );
+        return pc_->equivalent( code, bn );
       }
       else if( condition.category() == std::generic_category()
         || condition.category() == boost::system::generic_category() )
       {
-        boost::system::error_code bc( code, *pc_ );
         boost::system::error_condition bn( condition.value(),
           boost::system::generic_category() );
 
-        return bc == bn;
+        return pc_->equivalent( code, bn );
       }
 #ifndef BOOST_NO_RTTI
       else if( std_category const* pc2 = dynamic_cast< std_category const* >(
         &condition.category() ) )
       {
-        boost::system::error_code bc( code, *pc_ );
         boost::system::error_condition bn( condition.value(), *pc2->pc_ );
-
-        return bc == bn;
+        return pc_->equivalent( code, bn );
       }
 #endif
       else
       {
-        return false;
+        return default_error_condition( code ) == condition;
       }
     }
 
     inline bool error_category::std_category::equivalent( const std::error_code & code,
       int condition ) const BOOST_NOEXCEPT
     {
-      if( *this == code.category() && code.value() == condition )
+      if( code.category() == *this )
       {
-        return true;
+        boost::system::error_code bc( code.value(), *pc_ );
+        return pc_->equivalent( bc, condition );
       }
+      else if( code.category() == std::generic_category()
+        || code.category() == boost::system::generic_category() )
+      {
+        boost::system::error_code bc( code.value(),
+          boost::system::generic_category() );
+
+        return pc_->equivalent( bc, condition );
+      }
+#ifndef BOOST_NO_RTTI
+      else if( std_category const* pc2 = dynamic_cast< std_category const* >(
+        &code.category() ) )
+      {
+        boost::system::error_code bc( code.value(), *pc2->pc_ );
+        return pc_->equivalent( bc, condition );
+      }
+#endif
       else if( *pc_ == boost::system::generic_category() )
       {
-        return code == std::error_condition( condition, std::generic_category() );
+        return std::generic_category().equivalent( code, condition );
       }
       else
       {