Math: Color4::{xyz,rgb}() should return Color3, not Vector3.

src/Magnum/Math/Color.h

@@ -947,9 +947,18 @@ class Color4: public Vector4<T> {
          * @see @ref fromXyz()
          */
         Vector3<FloatingPointType> toXyz() const {
-            return Implementation::toXyz<T>(Vector4<T>::rgb());
+            return Implementation::toXyz<T>(rgb());
         }
 
+        /* Overloads to remove WTF-factor from return types */
+        #ifndef DOXYGEN_GENERATING_OUTPUT
+        Color3<T>& xyz() { return Color3<T>::from(Vector4<T>::data()); }
+        constexpr const Color3<T> xyz() const { return Vector4<T>::xyz(); }
+
+        Color3<T>& rgb() { return xyz(); }
+        constexpr const Color3<T> rgb() const { return xyz(); }
+        #endif
+
         MAGNUM_VECTOR_SUBCLASS_IMPLEMENTATION(4, Color4)
 };
 

src/Magnum/Math/Test/ColorTest.cpp

@@ -79,6 +79,8 @@ struct ColorTest: Corrade::TestSuite::Tester {
     void constructCopy();
     void convert();
 
+    void data();
+
     void literals();
 
     void colors();
@@ -125,6 +127,8 @@ ColorTest::ColorTest() {
               &ColorTest::constructCopy,
               &ColorTest::convert,
 
+              &ColorTest::data,
+
               &ColorTest::literals,
 
               &ColorTest::colors,
@@ -333,6 +337,25 @@ void ColorTest::convert() {
     CORRADE_VERIFY(!(std::is_convertible<Color4, Vec4>::value));
 }
 
+void ColorTest::data() {
+    Color4 c{1.0f, 2.0f, 3.0f, 4.0f};
+    constexpr const Color4 cc{1.0f, 2.0f, 3.0f, 4.0f};
+
+    Color3 c3a = c.rgb();
+    Color3 c3b = c.xyz();
+    constexpr Color3 cc3a{cc.rgb()};
+    constexpr Color3 cc3b{cc.xyz()};
+    CORRADE_COMPARE(c3a, (Color3{1.0f, 2.0f, 3.0f}));
+    CORRADE_COMPARE(c3b, (Color3{1.0f, 2.0f, 3.0f}));
+    CORRADE_COMPARE(cc3a, (Color3{1.0f, 2.0f, 3.0f}));
+    CORRADE_COMPARE(cc3b, (Color3{1.0f, 2.0f, 3.0f}));
+
+    CORRADE_VERIFY((std::is_same<decltype(c.xyz()), Color3&>::value));
+    CORRADE_VERIFY((std::is_same<decltype(cc.xyz()), const Color3>::value));
+    CORRADE_VERIFY((std::is_same<decltype(c.rgb()), Color3&>::value));
+    CORRADE_VERIFY((std::is_same<decltype(cc.rgb()), const Color3>::value));
+}
+
 void ColorTest::literals() {
     using namespace Literals;