diff -r d4baf4dd55c3 -r fe0d69d72bcd src/cx/iterator.h
--- a/src/cx/iterator.h	Thu May 23 19:29:14 2024 +0200
+++ b/src/cx/iterator.h	Thu May 23 20:29:28 2024 +0200
@@ -38,45 +38,54 @@
 
 #include "common.h"
 
-#define CX_ITERATOR_BASE \
-    /** \
-     * True iff the iterator points to valid data. \
-     */ \
-    __attribute__ ((__nonnull__)) \
-    bool (*valid)(void const *); \
-    /** \
-     * Returns a pointer to the current element. \
-     * \
-     * When valid returns false, the behavior of this function is undefined. \
-     */ \
-    __attribute__ ((__nonnull__)) \
-    void *(*current)(void const *); \
-    /** \
-     * Original implementation in case the function needs to be wrapped. \
-     */ \
-    __attribute__ ((__nonnull__)) \
-    void *(*current_impl)(void const *); \
-    /** \
-     * Advances the iterator. \
-     * \
-     * When valid returns false, the behavior of this function is undefined. \
-     */ \
-    __attribute__ ((__nonnull__)) \
-    void (*next)(void *); \
-    /** \
-     * Indicates whether this iterator may remove elements. \
-     */ \
-    bool mutating; \
-    /** \
-     * Internal flag for removing the current element when advancing. \
-     */ \
+struct cx_iterator_base_s {
+    /**
+     * True iff the iterator points to valid data.
+     */
+    __attribute__ ((__nonnull__))
+    bool (*valid)(void const *);
+
+    /**
+     * Returns a pointer to the current element.
+     *
+     * When valid returns false, the behavior of this function is undefined.
+     */
+    __attribute__ ((__nonnull__))
+    void *(*current)(void const *);
+
+    /**
+     * Original implementation in case the function needs to be wrapped.
+     */
+    __attribute__ ((__nonnull__))
+    void *(*current_impl)(void const *);
+
+    /**
+     * Advances the iterator.
+     *
+     * When valid returns false, the behavior of this function is undefined.
+     */
+    __attribute__ ((__nonnull__))
+    void (*next)(void *);
+    /**
+     * Indicates whether this iterator may remove elements.
+     */
+    bool mutating;
+    /**
+     * Internal flag for removing the current element when advancing.
+     */
     bool remove;
+};
+
+/**
+ * Declares base attributes for an iterator.
+ */
+#define CX_ITERATOR_BASE struct cx_iterator_base_s base
 
 /**
  * Internal iterator struct - use CxIterator.
  */
 struct cx_iterator_s {
-    CX_ITERATOR_BASE
+    CX_ITERATOR_BASE;
 
     /**
      * Handle for the current element.
@@ -157,7 +166,7 @@
  * @param iter the iterator
  * @return true iff the iterator points to valid data
  */
-#define cxIteratorValid(iter) (iter).valid(&(iter))
+#define cxIteratorValid(iter) (iter).base.valid(&(iter))
 
 /**
  * Returns a pointer to the current element.
@@ -167,21 +176,21 @@
  * @param iter the iterator
  * @return a pointer to the current element
  */
-#define cxIteratorCurrent(iter) (iter).current(&iter)
+#define cxIteratorCurrent(iter) (iter).base.current(&iter)
 
 /**
  * Advances the iterator to the next element.
  *
  * @param iter the iterator
  */
-#define cxIteratorNext(iter) (iter).next(&iter)
+#define cxIteratorNext(iter) (iter).base.next(&iter)
 
 /**
  * Flags the current element for removal, if this iterator is mutating.
  *
  * @param iter the iterator
  */
-#define cxIteratorFlagRemoval(iter) (iter).remove |= (iter).mutating
+#define cxIteratorFlagRemoval(iter) (iter).base.remove |= (iter).base.mutating
 
 /**
  * Loops over an iterator.