[iter] Make hb_is_iterator_of() check is_convertible

Instead of is_cr_convertible.

src/hb-array.hh

@@ -47,12 +47,12 @@ struct hb_array_t : hb_iter_with_fallback_t<hb_array_t<Type>, Type&>
   template <unsigned int length_> hb_array_t (Type (&array_)[length_]) : arrayZ (array_), length (length_) {}
 
   template <typename U,
-	    hb_enable_if (hb_is_cr_convertible_to(U, Type))>
+	    hb_enable_if (hb_is_cr_convertible(U, Type))>
   hb_array_t (const hb_array_t<U> &o) :
     hb_iter_with_fallback_t<hb_array_t<Type>, Type&> (),
     arrayZ (o.arrayZ), length (o.length) {}
   template <typename U,
-	    hb_enable_if (hb_is_cr_convertible_to(U, Type))>
+	    hb_enable_if (hb_is_cr_convertible(U, Type))>
   hb_array_t& operator = (const hb_array_t<U> &o)
   { arrayZ = o.arrayZ; length = o.length; return *this; }
 
@@ -228,12 +228,12 @@ struct hb_sorted_array_t :
   template <unsigned int length_> hb_sorted_array_t (Type (&array_)[length_]) : hb_array_t<Type> (array_) {}
 
   template <typename U,
-	    hb_enable_if (hb_is_cr_convertible_to(U, Type))>
+	    hb_enable_if (hb_is_cr_convertible(U, Type))>
   hb_sorted_array_t (const hb_array_t<U> &o) :
     hb_iter_t<hb_sorted_array_t<Type>, Type&> (),
     hb_array_t<Type> (o) {}
   template <typename U,
-	    hb_enable_if (hb_is_cr_convertible_to(U, Type))>
+	    hb_enable_if (hb_is_cr_convertible(U, Type))>
   hb_sorted_array_t& operator = (const hb_array_t<U> &o)
   { hb_array_t<Type> (*this) = o; return *this; }
 

src/hb-iter.hh

@@ -266,7 +266,7 @@ static inline char _hb_is_iterator_of (hb_priority<0>, const void *) { return 0;
 template <typename Iter,
 	  typename Item,
 	  typename Item2 = typename Iter::item_t,
-	  hb_enable_if (hb_is_cr_convertible_to (Item2, Item))>
+	  hb_enable_if (hb_is_convertible (Item2, Item))>
 static inline int _hb_is_iterator_of (hb_priority<2>, hb_iter_t<Iter, Item2> *) { return 0; }
 
 template<typename Iter, typename Item>

src/hb-meta.hh

@@ -116,10 +116,10 @@ template <typename T> using hb_remove_pointer = typename hb_match_pointer<T>::ty
 /* TODO Add feature-parity to std::decay. */
 template <typename T> using hb_decay = hb_remove_const<hb_remove_reference<T>>;
 
-#define hb_is_cr_convertible_to(A, B) ( \
-	hb_is_same (hb_decay<A>, hb_decay<B>) && \
-	hb_is_const (A) <= hb_is_const (B) && \
-	hb_is_reference (A) >= hb_is_reference (B))
+#define hb_is_cr_convertible(From, To) ( \
+	hb_is_same (hb_decay<From>, hb_decay<To>) && \
+	hb_is_const (From) <= hb_is_const (To) && \
+	hb_is_reference (From) >= hb_is_reference (To))