# HG changeset patch
# User Mike Becker <universe@uap-core.de>
# Date 1761492216 -3600
# Node ID 808688e304d540b239d533fc7caee0c95c5b3f70
# Parent  b6fc5b1d5c5d09e3570628073b8fb72368779a31
cxListDifference() sets the sorted flag if it can guarantee that

relates to #745

diff -r b6fc5b1d5c5d -r 808688e304d5 src/list.c
--- a/src/list.c	Sun Oct 26 16:16:43 2025 +0100
+++ b/src/list.c	Sun Oct 26 16:23:36 2025 +0100
@@ -900,6 +900,8 @@
 
     // now perform the difference calculation
     if (cxCollectionSorted(minuend) && cxCollectionSorted(subtrahend)) {
+        bool dst_was_empty = cxCollectionSize(dst) == 0;
+
         CxIterator min_iter = cxListIterator(minuend);
         CxIterator sub_iter = cxListIterator(subtrahend);
         while (cxIteratorValid(min_iter)) {
@@ -938,6 +940,9 @@
                 cxIteratorNext(min_iter);
             }
         }
+
+        // if dst was empty, it is now guaranteed to be sorted
+        dst->collection.sorted = dst_was_empty;
     } else {
         CxIterator min_iter = cxListIterator(minuend);
         cx_foreach(void *, elem, min_iter) {