; Add commentary to recent changes

* src/image.c (png_load_body):
* src/editfns.c (styled_format):
* src/casefiddle.c (do_casify_multibyte_string):
* src/alloc.c (free_cons): Comment why we use a signed
temporary integer variable.  (Bug#37006)

1 files changed, 2 insertions, 0 deletions

diff --git a/src/alloc.c b/src/alloc.c
index 8227feadae5..39833f8decb 100644
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -2542,6 +2542,8 @@ free_cons (struct Lisp_Cons *ptr)
   ptr->u.s.u.chain = cons_free_list;
   ptr->u.s.car = dead_object ();
   cons_free_list = ptr;
+  /* Use a temporary signed variable, since otherwise INT_ADD_WRAPV
+     might incorrectly return non-zero.  */
   int incr = sizeof *ptr;
   if (INT_ADD_WRAPV (consing_until_gc, incr, &consing_until_gc))
     consing_until_gc = OBJECT_CT_MAX;