From c02cd2b0042bc8ab3827e36a0faf04bff325d024 Mon Sep 17 00:00:00 2001
From: Peter Dimov <pdimov@gmail.com>
Date: Sun, 19 Sep 2021 05:24:08 +0300
Subject: [PATCH] Add private error_code::equals, use it in
 error_category::equivalent

---
 .../boost/system/detail/error_category.hpp    |  2 ++
 .../system/detail/error_category_impl.hpp     |  2 +-
 include/boost/system/detail/error_code.hpp    | 24 +++++++++++++++++++
 3 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/include/boost/system/detail/error_category.hpp b/include/boost/system/detail/error_category.hpp
index 693f75f..092fe7a 100644
--- a/include/boost/system/detail/error_category.hpp
+++ b/include/boost/system/detail/error_category.hpp
@@ -54,6 +54,8 @@ private:
 
     friend std::size_t hash_value( error_code const & ec );
     friend BOOST_SYSTEM_CONSTEXPR bool detail::failed_impl( int ev, error_category const & cat );
+
+    friend class error_code;
     friend class error_condition;
 
 #if !defined(BOOST_NO_CXX11_DELETED_FUNCTIONS)
diff --git a/include/boost/system/detail/error_category_impl.hpp b/include/boost/system/detail/error_category_impl.hpp
index 66f2f60..7052d18 100644
--- a/include/boost/system/detail/error_category_impl.hpp
+++ b/include/boost/system/detail/error_category_impl.hpp
@@ -38,7 +38,7 @@ inline bool error_category::equivalent( int code, const error_condition & condit
 
 inline bool error_category::equivalent( const error_code & code, int condition ) const BOOST_NOEXCEPT
 {
-    return *this == code.category() && code.value() == condition;
+    return code.equals( condition, *this );
 }
 
 inline char const * error_category::message( int ev, char * buffer, std::size_t len ) const BOOST_NOEXCEPT
diff --git a/include/boost/system/detail/error_code.hpp b/include/boost/system/detail/error_code.hpp
index 68c73c5..0984be7 100644
--- a/include/boost/system/detail/error_code.hpp
+++ b/include/boost/system/detail/error_code.hpp
@@ -285,6 +285,30 @@ public:
 
     // relationals:
 
+private:
+
+    // private equality for use in error_category::equivalent
+
+    friend class error_category;
+
+    BOOST_SYSTEM_CONSTEXPR bool equals( int val, error_category const& cat ) const BOOST_NOEXCEPT
+    {
+        if( lc_flags_ == 0 )
+        {
+            return val == 0 && cat.id_ == detail::system_category_id;
+        }
+        else if( lc_flags_ == 1 )
+        {
+            return cat.id_ == detail::interop_category_id && val == value();
+        }
+        else
+        {
+            return val == d1_.val_ && cat == *d1_.cat_;
+        }
+    }
+
+public:
+
     //  the more symmetrical non-member syntax allows enum
     //  conversions work for both rhs and lhs.