GCC 4.6 compatibility: no delegating ctr in Math::RectangularMatrix.

src/Math/RectangularMatrix.h

@@ -112,7 +112,13 @@ template<std::size_t cols, std::size_t rows, class T> class RectangularMatrix {
          * // integral == {1, 2, -15, 7}
          * @endcode
          */
+        #ifndef CORRADE_GCC46_COMPATIBILITY
         template<class U> inline constexpr explicit RectangularMatrix(const RectangularMatrix<cols, rows, U>& other): RectangularMatrix(typename Implementation::GenerateSequence<cols>::Type(), other) {}
+        #else
+        template<class U> inline explicit RectangularMatrix(const RectangularMatrix<cols, rows, U>& other) {
+            *this = RectangularMatrix(typename Implementation::GenerateSequence<cols>::Type(), other);
+        }
+        #endif
 
         /** @brief Copy constructor */
         inline constexpr RectangularMatrix(const RectangularMatrix<cols, rows, T>&) = default;

src/Math/Test/RectangularMatrixTest.cpp

@@ -193,13 +193,15 @@ void RectangularMatrixTest::constExpressions() {
                                  Vector4(4.5f,  4.0f, 7.0f, 3.0f),
                                  Vector4(7.0f, -1.7f, 8.0f, 0.0f)));
 
-    /* Conversion constructor */
+    /* Conversion constructor, not constexpr under GCC < 4.7 */
+    #ifndef CORRADE_GCC46_COMPATIBILITY
     typedef RectangularMatrix<3, 4, Int> Matrix3x4i;
     typedef Vector<4, Int> Vector4i;
     constexpr Matrix3x4i c(b);
     CORRADE_COMPARE(c, Matrix3x4i(Vector4i(3,  5, 8, 4),
                                   Vector4i(4,  4, 7, 3),
                                   Vector4i(7, -1, 8, 0)));
+    #endif
 
     /* Copy constructor */
     constexpr Matrix3x4 d(b);