Add private error_code::equals, use it in error_category::equivalent

doc/system/reference.adoc

@@ -725,7 +725,7 @@ constexpr void assign( int val, const error_category & cat ) noexcept;
 [none]
 * {blank}
 +
-Effects: :: `*this = error_code( val, cat );`.
+Effects: :: `*this = error_code( val, cat )`.
 
 ```
 void assign( int val, const error_category & cat,
@@ -734,7 +734,7 @@ void assign( int val, const error_category & cat,
 [none]
 * {blank}
 +
-Effects: :: `*this = error_code( val, cat, loc );`.
+Effects: :: `*this = error_code( val, cat, loc )`.
 
 ```
 template<typename ErrorCodeEnum>
@@ -753,7 +753,7 @@ constexpr void clear() noexcept;
 * {blank}
 +
 Effects: ::
-  `*this = error_code();`.
+  `*this = error_code()`.
 
 #### Observers
 
@@ -1700,8 +1700,8 @@ template<class Ch, class Tr, class T, class E>
 * {blank}
 +
 Effects: ::
-  - If `*this` holds a value `t`, `os << "value:" << t;`.
-  - If `*this` holds an error `e`, `os << "error:" << e;`.
+  - If `*this` holds a value `t`, `os << "value:" << t`.
+  - If `*this` holds an error `e`, `os << "error:" << e`.
 Returns: ::
   `os`.
 
@@ -1943,8 +1943,8 @@ template<class Ch, class Tr, class E>
 * {blank}
 +
 Effects: ::
-  - If `*this` holds a value, `os << "value:void";`.
-  - If `*this` holds an error `e`, `os << "error:" << e;`.
+  - If `*this` holds a value, `os << "value:void"`.
+  - If `*this` holds an error `e`, `os << "error:" << e`.
 Returns: ::
   `os`.
 

include/boost/system/detail/error_category.hpp

@@ -55,6 +55,9 @@ 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)
 public:
 

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

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.
 

include/boost/system/detail/error_condition.hpp

@@ -47,6 +47,13 @@ private:
     int val_;
     error_category const * cat_;
 
+private:
+
+    boost::ulong_long_type cat_id() const BOOST_NOEXCEPT
+    {
+        return cat_? cat_->id_: detail::generic_category_id;
+    }
+
 public:
 
     // constructors:
@@ -180,7 +187,22 @@ public:
 
     BOOST_SYSTEM_CONSTEXPR inline friend bool operator==( const error_condition & lhs, const error_condition & rhs ) BOOST_NOEXCEPT
     {
-        return lhs.val_ == rhs.val_ && lhs.category() == rhs.category();
+        if( lhs.val_ != rhs.val_ )
+        {
+            return false;
+        }
+        else if( lhs.cat_ == 0 )
+        {
+            return rhs.cat_id() == detail::generic_category_id;
+        }
+        else if( rhs.cat_ == 0 )
+        {
+            return lhs.cat_id() == detail::generic_category_id;
+        }
+        else
+        {
+            return *lhs.cat_ == *rhs.cat_;
+        }
     }
 
     BOOST_SYSTEM_CONSTEXPR inline friend bool operator<( const error_condition & lhs, const error_condition & rhs ) BOOST_NOEXCEPT