Define operator!= in terms of operator== (gbdev#1659)

include/gfx/rgba.hpp

@@ -36,8 +36,9 @@ struct Rgba {
 		auto shl = [](uint8_t val, unsigned shift) { return static_cast<uint32_t>(val) << shift; };
 		return shl(red, 24) | shl(green, 16) | shl(blue, 8) | shl(alpha, 0);
 	}
+
 	bool operator==(Rgba const &rhs) const { return toCSS() == rhs.toCSS(); }
-	bool operator!=(Rgba const &rhs) const { return toCSS() != rhs.toCSS(); }
+	bool operator!=(Rgba const &rhs) const { return !operator==(rhs); }
 
 	// CGB colors are RGB555, so we use bit 15 to signify that the color is transparent instead
 	// Since the rest of the bits don't matter then, we return 0x8000 exactly.

include/itertools.hpp

@@ -25,7 +25,7 @@ class EnumSeq {
 		auto operator*() const { return _value; }
 
 		bool operator==(Iterator const &rhs) const { return _value == rhs._value; }
-		bool operator!=(Iterator const &rhs) const { return _value != rhs._value; }
+		bool operator!=(Iterator const &rhs) const { return !operator==(rhs); }
 	};
 
 public:
@@ -59,10 +59,7 @@ class ZipIterator {
 	bool operator==(ZipIterator const &rhs) const {
 		return std::get<0>(_iters) == std::get<0>(rhs._iters);
 	}
-
-	bool operator!=(ZipIterator const &rhs) const {
-		return std::get<0>(_iters) != std::get<0>(rhs._iters);
-	}
+	bool operator!=(ZipIterator const &rhs) const { return !operator==(rhs); }
 };
 
 template<typename... Ts>

src/gfx/pal_packing.cpp

@@ -86,8 +86,9 @@ class AssignedProtos {
 	public:
 		Iter() = default;
 
-		bool operator==(Iter const &other) const { return _iter == other._iter; }
-		bool operator!=(Iter const &other) const { return !(*this == other); }
+		bool operator==(Iter const &rhs) const { return _iter == rhs._iter; }
+		bool operator!=(Iter const &rhs) const { return !operator==(rhs); }
+
 		Iter &operator++() {
 			++_iter;
 			skipEmpty();
@@ -98,6 +99,7 @@ class AssignedProtos {
 			++(*this);
 			return it;
 		}
+
 		reference operator*() const {
 			assume((*_iter).has_value());
 			return **_iter;

src/gfx/process.cpp

@@ -466,7 +466,7 @@ class Png {
 			}
 
 			bool operator==(Iterator const &rhs) const { return coords() == rhs.coords(); }
-			bool operator!=(Iterator const &rhs) const { return coords() != rhs.coords(); }
+			bool operator!=(Iterator const &rhs) const { return !operator==(rhs); }
 		};
 
 	public: