Math: properly testing all constexpr methods in Vector.

Fixed conversion constructor, as pointer chasings are not allowed in
constexpr functions.

src/Math/Test/VectorTest.cpp

@@ -33,6 +33,8 @@ class VectorTest: public Corrade::TestSuite::Tester {
         void constructConversion();
         void data();
 
+        void constExpressions();
+
         void negative();
         void addSubtract();
         void multiplyDivide();
@@ -73,6 +75,8 @@ VectorTest::VectorTest() {
              &VectorTest::constructConversion,
              &VectorTest::data,
 
+             &VectorTest::constExpressions,
+
              &VectorTest::negative,
              &VectorTest::addSubtract,
              &VectorTest::multiplyDivide,
@@ -141,6 +145,34 @@ void VectorTest::data() {
     CORRADE_COMPARE(vector, Vector4(4.0f, 5.0f, 1.0f, 1.5f));
 }
 
+void VectorTest::constExpressions() {
+    /* Default constructor */
+    constexpr Vector4 a;
+    CORRADE_COMPARE(a, Vector4(0.0f, 0.0f, 0.0f, 0.0f));
+
+    /* Value constructor */
+    constexpr Vector4 b(1.0f, 3.5f, 4.0f, -2.7f);
+    CORRADE_COMPARE(b, Vector4(1.0f, 3.5f, 4.0f, -2.7f));
+
+    /* One-value constructor */
+    constexpr Vector4 c(7.0f);
+    CORRADE_COMPARE(c, Vector4(7.0f, 7.0f, 7.0f, 7.0f));
+
+    /* Conversion constructor */
+    constexpr Vector4i d(b);
+    CORRADE_COMPARE(d, Vector4i(1, 3, 4, -2));
+
+    /* Copy constructor */
+    constexpr Vector4 e(b);
+    CORRADE_COMPARE(e, Vector4(1.0f, 3.5f, 4.0f, -2.7f));
+
+    /* Data access, pointer chasings, i.e. *(b.data()[3]), are not possible */
+    constexpr float f = b[3];
+    constexpr float g = *b.data();
+    CORRADE_COMPARE(f, -2.7f);
+    CORRADE_COMPARE(g, 1.0f);
+}
+
 void VectorTest::compare() {
     CORRADE_VERIFY(Vector4(1.0f, -3.5f, 5.0f, -10.0f) == Vector4(1.0f + MathTypeTraits<float>::epsilon()/2, -3.5f, 5.0f, -10.0f));
     CORRADE_VERIFY(Vector4(1.0f, -1.0f, 5.0f, -10.0f) != Vector4(1.0f, -1.0f + MathTypeTraits<float>::epsilon()*2, 5.0f, -10.0f));

src/Math/Vector.h

@@ -513,7 +513,7 @@ template<std::size_t size, class T> class Vector {
 
     private:
         /* Implementation for Vector<size, T>::Vector(const Vector<size, U>&) */
-        template<class U, std::size_t ...sequence> inline constexpr explicit Vector(Implementation::Sequence<sequence...>, const Vector<sizeof...(sequence), U>& vector): _data{T(vector.data()[sequence])...} {}
+        template<class U, std::size_t ...sequence> inline constexpr explicit Vector(Implementation::Sequence<sequence...>, const Vector<sizeof...(sequence), U>& vector): _data{T(vector._data[sequence])...} {}
 
         /* Implementation for Vector<size, T>::Vector(U) */
         template<std::size_t ...sequence> inline constexpr explicit Vector(Implementation::Sequence<sequence...>, T value): _data{Implementation::repeat(value, sequence)...} {}