(mark_object): Add debugging code to check for ptr clobbered.

1 files changed, 4 insertions, 0 deletions

diff --git a/src/alloc.c b/src/alloc.c
index 48117d4e356..a6f554ad086 100644
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -1623,7 +1623,11 @@ mark_object (objptr)
             XUNMARK (obj);
             goto loop;
           }
+        if (ptr == 0)
+          abort ();
         mark_object (&ptr->car);
+        if (ptr == 0)
+          abort ();
         objptr = &ptr->cdr;
         obj = ptr->cdr;
         goto loop;