MSVC 2015 compatibility: issue with constexpr and delegating constructors.

src/Magnum/Array.h

@@ -76,7 +76,12 @@ template<UnsignedInt dimensions, class T> class Array {
         #ifdef DOXYGEN_GENERATING_OUTPUT
         constexpr /*implicit*/ Array(T value);
         #else
-        template<class U, class V = typename std::enable_if<std::is_same<T, U>::value && dimensions != 1, T>::type> constexpr /*implicit*/ Array(U value): Array(typename Math::Implementation::GenerateSequence<dimensions>::Type(), value) {}
+        template<class U, class V = typename std::enable_if<std::is_same<T, U>::value && dimensions != 1, T>::type>
+        #ifndef CORRADE_MSVC2015_COMPATIBILITY
+        /* Can't use delegating constructors with constexpr -- https://connect.microsoft.com/VisualStudio/feedback/details/1579279/c-constexpr-does-not-work-with-delegating-constructors */
+        constexpr
+        #endif
+        /*implicit*/ Array(U value): Array(typename Math::Implementation::GenerateSequence<dimensions>::Type(), value) {}
         #endif
 
         /** @brief Equality */

src/Magnum/Math/RectangularMatrix.h

@@ -108,7 +108,12 @@ template<std::size_t cols, std::size_t rows, class T> class RectangularMatrix {
         }
 
         /** @brief Construct zero-filled matrix */
-        constexpr /*implicit*/ RectangularMatrix(ZeroInitT = ZeroInit)
+        /** @todo Remove MSVC workaround when fixed */
+        #ifndef CORRADE_MSVC2015_COMPATIBILITY
+        /* Can't use delegating constructors with constexpr -- https://connect.microsoft.com/VisualStudio/feedback/details/1579279/c-constexpr-does-not-work-with-delegating-constructors */
+        constexpr
+        #endif
+        /*implicit*/ RectangularMatrix(ZeroInitT = ZeroInit)
             /** @todoc remove workaround when doxygen is sane */
             #ifndef DOXYGEN_GENERATING_OUTPUT
             /* MSVC 2015 can't handle {} here */

src/Magnum/Math/Vector.h

@@ -174,7 +174,12 @@ template<std::size_t size, class T> class Vector {
         #ifdef DOXYGEN_GENERATING_OUTPUT
         constexpr explicit Vector(T value);
         #else
-        template<class U, class V = typename std::enable_if<std::is_same<T, U>::value && size != 1, T>::type> constexpr explicit Vector(U value): Vector(typename Implementation::GenerateSequence<size>::Type(), value) {}
+        template<class U, class V = typename std::enable_if<std::is_same<T, U>::value && size != 1, T>::type>
+        #ifndef CORRADE_MSVC2015_COMPATIBILITY
+        /* Can't use delegating constructors with constexpr -- https://connect.microsoft.com/VisualStudio/feedback/details/1579279/c-constexpr-does-not-work-with-delegating-constructors */
+        constexpr
+        #endif
+        explicit Vector(U value): Vector(typename Implementation::GenerateSequence<size>::Type(), value) {}
         #endif
 
         /**
@@ -188,7 +193,12 @@ template<std::size_t size, class T> class Vector {
          * // integral == {1, 2, -15, 7}
          * @endcode
          */
-        template<class U> constexpr explicit Vector(const Vector<size, U>& other): Vector(typename Implementation::GenerateSequence<size>::Type(), other) {}
+        template<class U>
+        #ifndef CORRADE_MSVC2015_COMPATIBILITY
+        /* Can't use delegating constructors with constexpr -- https://connect.microsoft.com/VisualStudio/feedback/details/1579279/c-constexpr-does-not-work-with-delegating-constructors */
+        constexpr
+        #endif
+        explicit Vector(const Vector<size, U>& other): Vector(typename Implementation::GenerateSequence<size>::Type(), other) {}
 
         /** @brief Construct vector from external representation */
         template<class U, class V = decltype(Implementation::VectorConverter<size, T, U>::from(std::declval<U>()))> constexpr explicit Vector(const U& other): Vector(Implementation::VectorConverter<size, T, U>::from(other)) {}