+static void iter_from_extension(pb_field_iter_t *iter, pb_extension_t *extension)
+{
+ /* Fake a field iterator for the extension field.
+ * It is not actually safe to advance this iterator, but decode_field
+ * will not even try to. */
+ const pb_field_t *field = (const pb_field_t*)extension->type->arg;
+ (void)pb_field_iter_begin(iter, field, extension->dest);
+ iter->pData = extension->dest;
+ iter->pSize = &extension->found;
+
+ if (PB_ATYPE(field->type) == PB_ATYPE_POINTER)
+ {
+ /* For pointer extensions, the pointer is stored directly
+ * in the extension structure. This avoids having an extra
+ * indirection. */
+ iter->pData = &extension->dest;
+ }
+}
+