clarify overloading int with Style

Author: victor-mlai

README.md

@@ -375,11 +375,15 @@ we will define static variables for each enum entry.
 * Inspired by the [memory_order change in the standard](https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/p0439r0.html)
 
 * If the enum was used as bit flags, define bitwise operators as well.
+And if there were methods that recieved the unscoped enum as `int`,
+overload them to receive the scoped enum now (since the bitwise operators return the scoped enum,
+if they were to return an `int`, users will not be able to chain more than 2 of them: e.g.
+`Print(STYLE_BOLD | STYLE_ITALLIC | STYLE_STRIKE_THROUGH) // operator|(Style, int) is not overloaded`).
 
 ```cpp
 // Add `friend` if the enum lies inside a `struct`
 [friend] inline Style operator|(Style lhs, Style rhs) {
-    return Style{static_cast<int>(lhs) | static_cast<int>(rhs)};
+    return static_cast<Style>(static_cast<int>(lhs) | static_cast<int>(rhs));
 }
 ```
 

some_unstable_lib/include/ChangeToEnumClass.hpp

@@ -1,4 +1,6 @@
 #pragma once
+#include <string>       // string_view
+#include <type_traits>  // underlying_type_t
 
 struct Text {
 #ifndef BC_API_CHANGED
@@ -24,7 +26,13 @@ struct Text {
     // If the enum was used as bit flags, define bitwise operators as well.
     friend inline Style operator|(Style lhs, Style rhs) {
         using ut = std::underlying_type_t<Style>;
-        return Style{static_cast<ut>(lhs) | static_cast<ut>(rhs)};
+        return static_cast<Style>(static_cast<ut>(lhs) | static_cast<ut>(rhs));
     }
 #endif
 };
+
+// If you have methods that received Style as int, overload them to receive Style
+void Print(std::string_view /*text*/, int /*style*/) {}
+#ifdef BC_API_CHANGED
+void Print(std::string_view /*text*/, Text::Style /*style*/) {}
+#endif

tests/ChangeToEnumClassTest.cpp

@@ -1,13 +1,12 @@
-#include <string>
 #include "ChangeToEnumClass.hpp"
 #include "gtest/gtest.h"
 
-void Print(std::string_view /*text*/, Text::Style /*style*/) {}
-
 TEST(ChangeToEnumClass, Basic) {
-    Print("test", {});
+    Print("test", 0);
     Print("test", Text::STYLE_BOLD);
     Print("test", Text::STYLE_BOLD | Text::Style::STYLE_ITALLIC);
     Print("test", Text::Style::STYLE_BOLD | Text::STYLE_ITALLIC);
-    Print("test", Text::Style::STYLE_BOLD | Text::Style::STYLE_ITALLIC);
+    Print("test", Text::STYLE_BOLD | Text::STYLE_ITALLIC | Text::STYLE_STRIKE_THROUGH);
+    Print("test",
+          Text::Style::STYLE_BOLD | Text::Style::STYLE_ITALLIC | Text::Style::STYLE_STRIKE_THROUGH);
 }