Fix to only exclude hash<nonstd::monostate>, not hash<nonstd::variant> when variant_CONFIG_MONOSTATE is defined

Note: currently one cannot (yet) do `-Dvariant_CONFIG_MONOSTATE=nonstd::monostate` to get the default behaviour.
Same holds for `-Dvariant_CONFIG_BAD_VARIANT_ACCESS=nonstd::bad_variant_access`.

Author: martinmoene

include/nonstd/variant.hpp

@@ -1213,8 +1213,11 @@ class variant;
 // 19.7.8 Class monostate
 
 #ifdef variant_CONFIG_MONOSTATE
+
 using variant_CONFIG_MONOSTATE;
+
 #else
+
 class monostate{};
 
 // 19.7.9 monostate relational operators
@@ -1224,7 +1227,8 @@ inline variant_constexpr bool operator<=( monostate, monostate ) variant_noexcep
 inline variant_constexpr bool operator>=( monostate, monostate ) variant_noexcept { return true;  }
 inline variant_constexpr bool operator==( monostate, monostate ) variant_noexcept { return true;  }
 inline variant_constexpr bool operator!=( monostate, monostate ) variant_noexcept { return false; }
-#endif
+
+#endif // variant_CONFIG_MONOSTATE
 
 // 19.7.4 variant helper classes
 
@@ -1298,7 +1302,7 @@ class variant_nodiscard bad_variant_access : public std::exception
         return "bad variant access";
     }
 };
-#endif
+#endif // variant_CONFIG_BAD_VARIANT_ACCESS
 
 #endif // variant_CONFIG_NO_EXCEPTIONS
 
@@ -2705,12 +2709,14 @@ using namespace variants;
 
 } // namespace nonstd
 
-#if ! defined (variant_CONFIG_MONOSTATE) && variant_CPP11_OR_GREATER
+#if variant_CPP11_OR_GREATER
 
 // 19.7.12 Hash support
 
 namespace std {
 
+#ifndef variant_CONFIG_MONOSTATE
+
 template<>
 struct hash< nonstd::monostate >
 {
@@ -2720,6 +2726,8 @@ struct hash< nonstd::monostate >
     }
 };
 
+#endif // variant_CONFIG_MONOSTATE
+
 template< class T0, class T1, class T2, class T3, class T4, class T5, class T6, class T7, class T8, class T9, class T10, class T11, class T12, class T13, class T14, class T15 >
 struct hash< nonstd::variant<T0, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15> >
 {
@@ -2753,7 +2761,7 @@ struct hash< nonstd::variant<T0, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T
 
 } //namespace std
 
-#endif // ! defined (variant_CONFIG_MONOSTATE) && variant_CPP11_OR_GREATER
+#endif // variant_CPP11_OR_GREATER
 
 #if variant_BETWEEN( variant_COMPILER_MSVC_VER, 1300, 1900 )
 # pragma warning( pop )

template/variant.hpp

@@ -1088,8 +1088,11 @@ class variant;
 // 19.7.8 Class monostate
 
 #ifdef variant_CONFIG_MONOSTATE
+
 using variant_CONFIG_MONOSTATE;
+
 #else
+
 class monostate{};
 
 // 19.7.9 monostate relational operators
@@ -1099,6 +1102,7 @@ inline variant_constexpr bool operator<=( monostate, monostate ) variant_noexcep
 inline variant_constexpr bool operator>=( monostate, monostate ) variant_noexcept { return true;  }
 inline variant_constexpr bool operator==( monostate, monostate ) variant_noexcept { return true;  }
 inline variant_constexpr bool operator!=( monostate, monostate ) variant_noexcept { return false; }
+
 #endif // variant_CONFIG_MONOSTATE
 
 // 19.7.4 variant helper classes
@@ -2050,12 +2054,14 @@ using namespace variants;
 
 } // namespace nonstd
 
-#if ! defined (variant_CONFIG_MONOSTATE) && variant_CPP11_OR_GREATER
+#if variant_CPP11_OR_GREATER
 
 // 19.7.12 Hash support
 
 namespace std {
 
+#ifndef variant_CONFIG_MONOSTATE
+
 template<>
 struct hash< nonstd::monostate >
 {
@@ -2065,6 +2071,8 @@ struct hash< nonstd::monostate >
     }
 };
 
+#endif // variant_CONFIG_MONOSTATE
+
 template< {{TplParamsList}} >
 struct hash< nonstd::variant<{{TplArgsList}}> >
 {
@@ -2084,7 +2092,7 @@ struct hash< nonstd::variant<{{TplArgsList}}> >
 
 } //namespace std
 
-#endif // ! defined (variant_CONFIG_MONOSTATE) && variant_CPP11_OR_GREATER
+#endif // variant_CPP11_OR_GREATER
 
 #if variant_BETWEEN( variant_COMPILER_MSVC_VER, 1300, 1900 )
 # pragma warning( pop )