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, 2 deletions

diff --git a/src/itree.h b/src/itree.h
index 7fdc9c07c93..5733ec15305 100644
--- a/src/itree.h
+++ b/src/itree.h
@@ -112,7 +112,7 @@ enum interval_tree_order {
   ITREE_PRE_ORDER,
 };
 
-void interval_node_init (struct interval_node *, ptrdiff_t, ptrdiff_t, bool, bool, Lisp_Object);
+void interval_node_init (struct interval_node *, bool, bool, Lisp_Object);
 ptrdiff_t interval_node_begin (struct interval_tree *, struct interval_node *);
 ptrdiff_t interval_node_end (struct interval_tree *, struct interval_node *);
 void interval_node_set_region (struct interval_tree *, struct interval_node *, ptrdiff_t, ptrdiff_t);
@@ -120,7 +120,8 @@ struct interval_tree *interval_tree_create (void);
 void interval_tree_destroy (struct interval_tree *);
 intmax_t interval_tree_size (struct interval_tree *);
 void interval_tree_clear (struct interval_tree *);
-void interval_tree_insert (struct interval_tree *, struct interval_node *);
+void itree_insert_node (struct interval_tree *tree, struct interval_node *node,
+                        ptrdiff_t begin, ptrdiff_t end);
 struct interval_node *interval_tree_remove (struct interval_tree *, struct interval_node *);
 struct interval_generator *interval_tree_iter_start (struct interval_tree *, ptrdiff_t, ptrdiff_t, enum interval_tree_order,
                                const char* file, int line);