Use enum class for flags

flags.h

// Usage:
// collision::Mask m = collision::Mask::JumpThrough | collision::Mask::Solid;
//
//	if ( (m & collision::Mask::Solid) != 0)
//	{
//		....
//	}
//

namespace collision
{
	enum class Mask : int
	{
		None = 0,
		Solid = 1 << 0,
		JumpThrough = 1 << 2
	};
}


inline collision::Mask operator|(collision::Mask lhs, collision::Mask rhs)
{
	return static_cast<collision::Mask>(static_cast<std::underlying_type<collision::Mask>::type>(lhs) | static_cast<std::underlying_type<collision::Mask>::type>(rhs));
}

inline collision::Mask operator&(collision::Mask lhs, collision::Mask rhs)
{
	return static_cast<collision::Mask>(static_cast<std::underlying_type<collision::Mask>::type>(lhs) & static_cast<std::underlying_type<collision::Mask>::type>(rhs));
}

inline bool operator!=(collision::Mask lhs, std::underlying_type<collision::Mask>::type rhs)
{
	return static_cast<std::underlying_type<collision::Mask>::type>(lhs) != rhs;
}