Solved: 32 - Constexpr and Nullptr

modules/09_cpp11/include/constexpr_nullptr.hpp

@@ -7,7 +7,7 @@ namespace cpp11 {
 enum class Color { Red, Green, Blue };
 
 [[nodiscard]] auto to_index(Color color) -> int;
-[[nodiscard]] auto square(int value) -> int;
+[[nodiscard]] constexpr auto square(const int value) -> int { return value * value; }
 [[nodiscard]] auto find_null(int* ptr) -> int*;
 
 }  // namespace cpp11