feat(extmarks): add "undo_restore" flag to opt out of undo-restoring

It is a design goal of extmarks that they allow precise tracking
of changes across undo/redo, including restore the exact positions
after a do/undo or undo/redo cycle. However this behavior is not useful
for all usecases. Many plugins won't keep marks around for long after
text changes, but uses them more like a cache until some external source
(like LSP semantic highlights) has fully updated to changed text and
then will explicitly readjust/replace extmarks as needed.

Add a "undo_restore" flag which is true by default (matches existing
behavior) but can be set to false to opt-out of this behavior.

Delete dead u_extmark_set() code.

1 files changed, 1 insertions, 1 deletions

diff --git a/src/nvim/marktree.c b/src/nvim/marktree.c
index 8ab9370e6c..3df659b8e1 100644
--- a/src/nvim/marktree.c
+++ b/src/nvim/marktree.c
@@ -2007,7 +2007,7 @@ void marktree_put_test(MarkTree *b, uint32_t ns, uint32_t id, int row, int col,
                        int end_row, int end_col, bool end_right)
 {
   MTKey key = { { row, col }, ns, id, 0,
-                mt_flags(right_gravity, 0), 0, NULL };
+                mt_flags(right_gravity, 0, false), 0, NULL };
   marktree_put(b, key, end_row, end_col, end_right);
 }