vim-patch:8.1.1205: BufReadPre may move the cursor #9980

Problem:    A BufReadPre autocommand may cause the cursor to move.
Solution:   Restore the cursor position after executing the autocommand,
            unless the autocommand moved it. (Christian Brabandt,
            closes vim/vim#4302, closes vim/vim#4294)
https://github.com/vim/vim/commit/a68e59590905da9b4448ff1fcac929ad1a18da9e

1 files changed, 24 insertions, 0 deletions

diff --git a/src/nvim/window.c b/src/nvim/window.c
index e737bfbd05..200c651d1e 100644
--- a/src/nvim/window.c
+++ b/src/nvim/window.c
@@ -5963,16 +5963,40 @@ void check_lnums(int do_curwin)
 {
   FOR_ALL_TAB_WINDOWS(tp, wp) {
     if ((do_curwin || wp != curwin) && wp->w_buffer == curbuf) {
+      // save the original cursor position and topline
+      wp->w_save_cursor.w_cursor_save = wp->w_cursor;
+      wp->w_save_cursor.w_topline_save = wp->w_topline;
+
       if (wp->w_cursor.lnum > curbuf->b_ml.ml_line_count) {
         wp->w_cursor.lnum = curbuf->b_ml.ml_line_count;
       }
       if (wp->w_topline > curbuf->b_ml.ml_line_count) {
         wp->w_topline = curbuf->b_ml.ml_line_count;
       }
+
+      // save the corrected cursor position and topline
+      wp->w_save_cursor.w_cursor_corr = wp->w_cursor;
+      wp->w_save_cursor.w_topline_corr = wp->w_topline;
     }
   }
 }
 
+/// Reset cursor and topline to its stored values from check_lnums().
+/// check_lnums() must have been called first!
+void reset_lnums(void)
+{
+  FOR_ALL_TAB_WINDOWS(tp, wp) {
+    if (wp->w_buffer == curbuf) {
+      // Restore the value if the autocommand didn't change it.
+      if (equalpos(wp->w_save_cursor.w_cursor_corr, wp->w_cursor)) {
+        wp->w_cursor = wp->w_save_cursor.w_cursor_save;
+      }
+      if (wp->w_save_cursor.w_topline_corr == wp->w_topline) {
+        wp->w_topline = wp->w_save_cursor.w_topline_save;
+      }
+    }
+  }
+}
 
 /*
  * A snapshot of the window sizes, to restore them after closing the help