src: move 'borrow' constructor to private

src/core.cpp

@@ -85,7 +85,7 @@ private:
 
             Complex *data = const_cast<Complex *>(z.data());
             size_t size = z.size();
-            return std::move(Vector<Complex>(data, size));
+            return Vector<Complex>::borrow(data, size);
         }
 
 public:

src/vector.hpp

@@ -12,6 +12,12 @@
 
 namespace array {
 
+/**
+ * Simple vector class capable of handling "borrowed" data.
+ *
+ * This is only needed for CppAD compatibility, to avoid copying data.
+ * Otherwise, we could just use std::vector.
+ */
 template <class Scalar>
 class Vector
 {
@@ -42,6 +48,10 @@ private:
             size_ = storage_.size();
         }
 
+    Vector(Scalar *data, size_t size)
+        : storage_(), data_(data), size_(size)
+        {}
+
 public:
     Vector()
         : storage_(), data_(storage_.data()), size_(storage_.size())
@@ -73,9 +83,11 @@ public:
             other.size_ = other.storage_.size();
         }
 
-    Vector(Scalar *data, size_t size)
-        : storage_(), data_(data), size_(size)
-        {}
+
+    static Vector borrow(Scalar *data, size_t size)
+        {
+            return Vector(data, size);
+        }
 
     Vector& operator=(const Vector& other)
         {