feature/noverlay 8e61648693: * src/itree.c (interval_tree_iter_start): Improve error message

[Stefan Monnier]

branch: feature/noverlay
commit 8e61648693c779a411aad5ce8ad3a493e4032155
Author: Stefan Monnier <monnier@iro.umontreal.ca>
Commit: Stefan Monnier <monnier@iro.umontreal.ca>

    * src/itree.c (interval_tree_iter_start): Improve error message
---
 src/itree.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/itree.c b/src/itree.c
index aa6fcc1bea..bdaa3fe09b 100644
--- a/src/itree.c
+++ b/src/itree.c
@@ -438,7 +438,12 @@ interval_tree_iter_start (struct interval_tree *tree,
                          const char* file, int line)
 {
   if (tree->iter_running)
-    emacs_abort ();
+    {
+      fprintf (stderr,
+               "Detected nested iteration!\nOuter: %s:%d\nInner: %s:%d\n",
+               tree->file, tree->line, file, line);
+      emacs_abort ();
+    }
   interval_generator_reset (tree->iter, begin, end, order);
   tree->iter_running = true;
   tree->file = file;