base: disable array::data() when the underlying object is a tuple.

doc/tutorial/02_cube.cpp

@@ -44,9 +44,11 @@ public:
         Ticker::Unref(m_camera);
     }
 
+    struct vertex { vec3 pos, color; };
+
     virtual bool init_draw() override
     {
-        array<vec3, vec3> mesh
+        array<vertex> mesh
         {
             // Front vertices/colors
             { vec3(-1.0, -1.0,  1.0), vec3(1.0, 0.0, 1.0) },

doc/tutorial/07_input.cpp

@@ -100,9 +100,11 @@ public:
         m_matrix = proj * view * model * anim;
     }
 
+    struct vertex { vec3 pos, color; };
+
     virtual bool init_draw() override
     {
-        array<vec3, vec3> mesh
+        array<vertex> mesh
         {
             // Front vertices/colors
             { vec3(-1.0, -1.0,  1.0), vec3(1.0, 0.0, 1.0) },

src/lol/base/array.h

@@ -444,6 +444,14 @@ class array : public array_base<std::tuple<T...>, array<T...>>
 private:
     using array_base<std::tuple<T...>, array<T...>>::array_base;
 
+    // Mark these as private: it’s dangerous to use data() with arrays of
+    // tuples because no assumption should be made about the tuple layout,
+    // not even the order of its members in memory.
+    inline void data() {}
+    inline void data() const {}
+    inline void bytes() {}
+    inline void bytes() const {}
+
 public:
     // GCC needs this but Clang doesn’t
     typedef std::tuple<T...> element_t;