Add debugging help for nested iterators (nug#58144)

When starting an iteration, store __FILE__ and __LINE__ where this
happens in the interval_tree structure.

* src/buffer.h (buffer_overlay_iter_start): New macro adding __FILE
and __LINE__.
(buffer_overlay_iter_start1): Renamed from ..._start.
* src/itree.h (struct interval_tree): Add file and line info.
* src/itree.c: (interval_tree_contains, interval_tree_nodes,
interval_tree_insert_gap): Pass __FILE__ and __LINE__ to iter_start.
(interval_tree_iter_start): Record file and line info in tree.

1 files changed, 6 insertions, 3 deletions

diff --git a/src/buffer.h b/src/buffer.h
index 7d6c693b0f2..097283be671 100644
--- a/src/buffer.h
+++ b/src/buffer.h
@@ -1457,13 +1457,16 @@ remove_buffer_overlay (struct buffer *b, struct Lisp_Overlay *ov)
 }
 
 INLINE void
-buffer_overlay_iter_start (struct buffer *b, ptrdiff_t begin, ptrdiff_t end,
-                           enum interval_tree_order order)
+buffer_overlay_iter_start1 (struct buffer *b, ptrdiff_t begin, ptrdiff_t end,
+                           enum interval_tree_order order, const char* file, int line)
 {
   if (b->overlays)
-    interval_tree_iter_start (b->overlays, begin, end, order);
+    interval_tree_iter_start (b->overlays, begin, end, order, file, line);
 }
 
+#define buffer_overlay_iter_start(b, begin, end, order) \
+  buffer_overlay_iter_start1 ((b), (begin), (end), (order), __FILE__, __LINE__)
+
 INLINE struct interval_node*
 buffer_overlay_iter_next (struct buffer *b)
 {