vim-patch:9.1.0407: Stuck with long line and half-page scrolling (#28704)

Problem:  No scrolling happens with half-page scrolling with line
          filling entire window when 'smoothscroll' is disabled.
          (Mathias Rav, after v9.1.0285)
Solution: Adjust amount to move cursor by so that it is moved the same
          number of lines as was scrolled, even when scrolling different
          number of lines than requested with 'nosmoothscroll'.

https://github.com/vim/vim/commit/58448e09be497a8abb595ae309b6edfbc8e0e05a

1 files changed, 7 insertions, 4 deletions

diff --git a/src/nvim/move.c b/src/nvim/move.c
index 66667cecc4..b07bc33b17 100644
--- a/src/nvim/move.c
+++ b/src/nvim/move.c
@@ -2412,8 +2412,10 @@ static int get_scroll_overlap(Direction dir)
   }
 }
 
-/// Scroll "count" lines with 'smoothscroll' in direction "dir".
-static bool scroll_with_sms(Direction dir, int count)
+/// Scroll "count" lines with 'smoothscroll' in direction "dir". Return true
+/// when scrolling happened. Adjust "curscount" for scrolling different amount
+/// of lines when 'smoothscroll' is disabled.
+static bool scroll_with_sms(Direction dir, int count, int *curscount)
 {
   int prev_sms = curwin->w_p_sms;
   colnr_T prev_skipcol = curwin->w_skipcol;
@@ -2435,6 +2437,7 @@ static bool scroll_with_sms(Direction dir, int count)
     while (curwin->w_skipcol > 0
            && curwin->w_topline < curbuf->b_ml.ml_line_count) {
       scroll_redraw(fixdir == FORWARD, 1);
+      *curscount += (fixdir == dir ? 1 : -1);
     }
   }
   curwin->w_p_sms = prev_sms;
@@ -2482,7 +2485,7 @@ int pagescroll(Direction dir, int count, bool half)
 
     // (Try to) scroll the window unless already at the end of the buffer.
     if (count > 0) {
-      nochange = scroll_with_sms(dir, count);
+      nochange = scroll_with_sms(dir, count, &curscount);
       curwin->w_cursor.lnum = prev_lnum;
       curwin->w_cursor.col = prev_col;
       curwin->w_curswant = prev_curswant;
@@ -2500,7 +2503,7 @@ int pagescroll(Direction dir, int count, bool half)
     // Scroll [count] times 'window' or current window height lines.
     count *= ((ONE_WINDOW && p_window > 0 && p_window < Rows - 1)
               ? MAX(1, (int)p_window - 2) : get_scroll_overlap(dir));
-    nochange = scroll_with_sms(dir, count);
+    nochange = scroll_with_sms(dir, count, &count);
 
     // Place cursor at top or bottom of window.
     validate_botline(curwin);