Tighten up handling of `otick`

Move args between `build_overlay` and `add_buffer_overlay`,
to try and keep buffer positions together with their buffer.
Be more strict in the `otick` values passed to `interval_tree_insert`.
Move a few things around to try and reduce dependencies through `.h` files.
Fix a thinko bug in `check_tree`.

* src/alloc.c (build_overlay): Remove `begin` and `end` args.

* src/buffer.c (add_buffer_overlay): Move from `buffer.h`.
Add `begin` and `end` args.
(copy_overlays): Adjust accordingly.
(Fmake_overlay): Use BUF_BEG and BUF_Z; adjust call to `build_overlay`
and `add_buffer_overlay`.
(Fmove_overlay): Use BUF_BEG and BUF_Z; Use the new `begin` and `end`
args of `add_buffer_overlay` so we don't need to use
`interval_node_set_region` when moving to a new buffer.
(remove_buffer_overlay, set_overlay_region): Move from `buffer.h`.

* src/buffer.h (set_overlay_region, add_buffer_overlay)
(remove_buffer_overlay): Move to `buffer.c`.
(build_overlay): Move from `lisp.h`.
(maybe_alloc_buffer_overlays): Delete function (inline into its only
caller).

* src/itree.c (interval_tree_insert): Move declaration `from buffer.h`.
(check_tree): Fix initial offset in call to `recurse_check_tree`.
Remove redundant check of the `limit` value.
(interval_node_init): Remove `begin` and `end` args.
(interval_tree_insert): Mark it as static.
Assert that the new node's `otick` should already be uptodate and its
new parent as well.
(itree_insert_node): New function.
(interval_tree_insert_gap): Assert the otick of the removed+added nodes
were uptodate and mark them as uptodate again after adjusting
their positions.
(interval_tree_inherit_offset): Check that the parent is at least as
uptodate as the child.

* src/lisp.h (build_overlay): Move to `buffer.h`.

* src/itree.h (interval_node_init): Adjust accordingly.
(interval_tree_insert): Remove declaration.
(itree_insert_node): New declaration.

1 files changed, 3 insertions, 5 deletions

diff --git a/src/alloc.c b/src/alloc.c
index 50968b7e121..00f2991f250 100644
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -3702,19 +3702,17 @@ build_symbol_with_pos (Lisp_Object symbol, Lisp_Object position)
   return val;
 }
 
-/* Return a new overlay with specified START, END and PLIST.  */
+/* Return a new (deleted) overlay with PLIST.  */
 
 Lisp_Object
-build_overlay (ptrdiff_t begin, ptrdiff_t end,
-               bool front_advance, bool rear_advance,
+build_overlay (bool front_advance, bool rear_advance,
                Lisp_Object plist)
 {
   struct Lisp_Overlay *p = ALLOCATE_PSEUDOVECTOR (struct Lisp_Overlay, plist,
                                                   PVEC_OVERLAY);
   Lisp_Object overlay = make_lisp_ptr (p, Lisp_Vectorlike);
   struct interval_node *node = xmalloc (sizeof (*node));
-  interval_node_init (node, begin, end, front_advance,
-                      rear_advance, overlay);
+  interval_node_init (node, front_advance, rear_advance, overlay);
   p->interval = node;
   p->buffer = NULL;
   set_overlay_plist (overlay, plist);