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, 2 deletions

diff --git a/src/nvim/api/deprecated.c b/src/nvim/api/deprecated.c
index 59b7fc18d6..906edb7b44 100644
--- a/src/nvim/api/deprecated.c
+++ b/src/nvim/api/deprecated.c
@@ -172,8 +172,7 @@ Integer nvim_buf_set_virtual_text(Buffer buffer, Integer src_id, Integer line, A
   decor.virt_text_width = width;
   decor.priority = 0;
 
-  extmark_set(buf, ns_id, NULL, (int)line, 0, -1, -1, &decor, true,
-              false, kExtmarkNoUndo, NULL);
+  extmark_set(buf, ns_id, NULL, (int)line, 0, -1, -1, &decor, true, false, false, NULL);
   return src_id;
 }