feature/noverlay b8fbd42f0a 1/2: mark_overlays: Use the normal ITREE_FOREACH

[Stefan Monnier]

branch: feature/noverlay
commit b8fbd42f0a7caa4cd9e2d50dd4e4b2101ac78acd
Author: Stefan Monnier <monnier@iro.umontreal.ca>
Commit: Stefan Monnier <monnier@iro.umontreal.ca>

    mark_overlays: Use the normal ITREE_FOREACH
    
    This commit basically reverts commit 5b954f8f9.  The problem of nested
    iterations hasn't been fixed in the mean time, but since the GC can
    run arbitrary ELisp code (via `post-gc-hook`), running the GC from
    within an itree iteration is already unsafe anyway :-(
    
    * src/alloc.c (mark_overlays): Delete function.
    (mark_buffer): Use ITREE_FOREACH.
---
 src/alloc.c | 20 +++-----------------
 src/itree.h |  3 ++-
 2 files changed, 5 insertions(+), 18 deletions(-)

diff --git a/src/alloc.c b/src/alloc.c
index db8f39a60e..50968b7e12 100644
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -6512,21 +6512,6 @@ mark_overlay (struct Lisp_Overlay *ov)
   mark_object (ov->plist);
 }
 
-static void
-mark_overlays (struct interval_tree *it, struct interval_node *in)
-{
-  /* `left/right` are set to NULL when the overlay is deleted, but
-     they use the `null` node instead when the overlay is not deleted
-     (i.e. is within an overlay tree).  */
-  eassert (in);
-  if (in == ITREE_NULL)
-    return;
-
-  mark_object (in->data);
-  mark_overlays (it, in->left);
-  mark_overlays (it, in->right);
-}
-
 /* Mark Lisp_Objects and special pointers in BUFFER.  */
 
 static void
@@ -6548,8 +6533,9 @@ mark_buffer (struct buffer *buffer)
   if (!BUFFER_LIVE_P (buffer))
       mark_object (BVAR (buffer, undo_list));
 
-  if (buffer->overlays)
-    mark_overlays (buffer->overlays, buffer->overlays->root);
+  struct interval_node *node;
+  ITREE_FOREACH (node, buffer->overlays, PTRDIFF_MIN, PTRDIFF_MAX, ASCENDING)
+    mark_object (node->data);
 
   /* If this is an indirect buffer, mark its base buffer.  */
   if (buffer->base_buffer &&
diff --git a/src/itree.h b/src/itree.h
index 1f019a2607..29bc8dd1b2 100644
--- a/src/itree.h
+++ b/src/itree.h
@@ -105,7 +105,8 @@ void interval_tree_delete_gap (struct interval_tree *, 
ptrdiff_t, ptrdiff_t);
    - The expression T may be evaluated more than once, so make sure
      it is cheap a pure.
    - Only a single iteration can happen at a time, so make sure none of the
-     code within the loop can start another tree_itertion.
+     code within the loop can start another tree iteration, i.e. it shouldn't
+     be able to run ELisp code (or GC for that matter).
    - If you need to exit the loop early, you *have* to call `ITREE_ABORT`
      just before exiting (e.g. with `break` or `return`).
    - Non-local exits are not supported within the body of the loop,