GCC 4.5 compatibility: GCC badly optimizes Matrix4::rotation*().

Redone in a way that the unit test passes.

src/Math/Matrix.h

@@ -248,6 +248,9 @@ template<size_t size, class T> class Matrix {
             return Matrix<size, T>(first, next...);
         }
 
+    #ifdef MAGNUM_GCC45_COMPATIBILITY
+    protected:
+    #endif
         /* Used internally instead of [][], because GCC does some heavy
            optimalization in release mode which breaks it */
         inline T& operator()(size_t col, size_t row) {
@@ -257,6 +260,9 @@ template<size_t size, class T> class Matrix {
             return _data[col*size+row];
         }
 
+    #ifdef MAGNUM_GCC45_COMPATIBILITY
+    private:
+    #endif
         T _data[size*size];
 };
 

src/Math/Matrix4.h

@@ -120,18 +120,31 @@ template<class T> class Matrix4: public Matrix<4, T> {
 
         /** @brief Rotation and scaling part of the matrix */
         inline Matrix3<T> rotationScaling() const {
+            #ifndef MAGNUM_GCC45_COMPATIBILITY /* GCC 4.5 badly optimizes this */
             return Matrix3<T>::from(
                 (*this)[0].xyz(),
                 (*this)[1].xyz(),
                 (*this)[2].xyz());
+            #else
+            return Matrix3<T>(
+                (*this)(0, 0), (*this)(0, 1), (*this)(0, 2),
+                (*this)(1, 0), (*this)(1, 1), (*this)(1, 2),
+                (*this)(2, 0), (*this)(2, 1), (*this)(2, 2));
+            #endif
         }
 
         /** @brief Rotation part of the matrix */
         inline Matrix3<T> rotation() const {
             return Matrix3<T>::from(
+                #ifndef MAGNUM_GCC45_COMPATIBILITY /* GCC 4.5 badly optimizes this */
                 (*this)[0].xyz().normalized(),
                 (*this)[1].xyz().normalized(),
                 (*this)[2].xyz().normalized());
+                #else
+                Vector3<T>((*this)(0, 0), (*this)(0, 1), (*this)(0, 2)).normalized(),
+                Vector3<T>((*this)(1, 0), (*this)(1, 1), (*this)(1, 2)).normalized(),
+                Vector3<T>((*this)(2, 0), (*this)(2, 1), (*this)(2, 2)).normalized());
+                #endif
         }
 
         MAGNUM_MATRIX_SUBCLASS_IMPLEMENTATION(Matrix4, Vector4, 4)