vim-patch:9.1.0285: Still problems with cursor position for CTRL-D/U

Problem:  Problems with cursor position when scrolling half a page.
Solution: Rework the cursor logic. (Luuk van Baal)

https://github.com/vim/vim/commit/78c51500f1bb16501521d721d52cb0982f5e70b6

3 files changed, 29 insertions, 25 deletions

diff --git a/src/nvim/move.c b/src/nvim/move.c
index 675f048d09..f3a79c08bf 100644
--- a/src/nvim/move.c
+++ b/src/nvim/move.c
@@ -2424,7 +2424,6 @@ static bool scroll_with_sms(Direction dir, int count)
     if (labs(curwin->w_topline - prev_topline) > (dir == BACKWARD)) {
       fixdir = dir * -1;
     }
-    validate_cursor(curwin);
     while (curwin->w_skipcol > 0
            && curwin->w_topline < curbuf->b_ml.ml_line_count) {
       scroll_redraw(fixdir == FORWARD, 1);
@@ -2447,6 +2446,7 @@ int pagescroll(Direction dir, int count, bool half)
   int nochange = true;
   int buflen = curbuf->b_ml.ml_line_count;
   colnr_T prev_col = curwin->w_cursor.col;
+  colnr_T prev_curswant = curwin->w_curswant;
   linenr_T prev_lnum = curwin->w_cursor.lnum;
   oparg_T oa = { 0 };
   cmdarg_T ca = { 0 };
@@ -2471,32 +2471,24 @@ int pagescroll(Direction dir, int count, bool half)
       }
     }
 
-    // Scroll the window and determine number of lines to move the cursor.
+    // (Try to) scroll the window unless already at the end of the buffer.
     if (count > 0) {
-      validate_cursor(curwin);
-      int prev_wrow = curwin->w_wrow;
       nochange = scroll_with_sms(dir, count);
-      if (!nochange) {
-        validate_cursor(curwin);
-        curscount = abs(prev_wrow - curwin->w_wrow);
-        dir = prev_wrow > curwin->w_wrow ? FORWARD : BACKWARD;
-      }
+      curwin->w_cursor.lnum = prev_lnum;
+      curwin->w_cursor.col = prev_col;
+      curwin->w_curswant = prev_curswant;
     }
 
-    int so = get_scrolloff_value(curwin);
-    // Move the cursor the same amount of screen lines except if
-    // 'scrolloff' is set and cursor was at start or end of buffer.
-    if (so == 0 || (prev_lnum != 1 && prev_lnum != buflen)) {
-      if (curwin->w_p_wrap) {
-        nv_screengo(&oa, dir, curscount);
-      } else if (dir == FORWARD) {
-        cursor_down_inner(curwin, curscount);
-      } else {
-        cursor_up_inner(curwin, curscount);
-      }
+    // Move the cursor the same amount of screen lines.
+    if (curwin->w_p_wrap) {
+      nv_screengo(&oa, dir, curscount);
+    } else if (dir == FORWARD) {
+      cursor_down_inner(curwin, curscount);
+    } else {
+      cursor_up_inner(curwin, curscount);
     }
 
-    if (so > 0) {
+    if (get_scrolloff_value(curwin) > 0) {
       cursor_correct(curwin);
     }
     // Move cursor to first line of closed fold.
diff --git a/test/old/testdir/test_normal.vim b/test/old/testdir/test_normal.vim
index 10fbf4125a..9f9d9367dc 100644
--- a/test/old/testdir/test_normal.vim
+++ b/test/old/testdir/test_normal.vim
@@ -4235,4 +4235,16 @@ func Test_single_line_filler_zb()
   bw!
 endfunc
 
+" Test for Ctrl-U not getting stuck at end of buffer with 'scrolloff'.
+func Test_halfpage_scrolloff_eob()
+  set scrolloff=5
+
+  call setline(1, range(1, 100))
+  exe "norm! Gzz\<C-U>zz"
+  call assert_notequal(100, line('.'))
+
+  set scrolloff&
+  bwipe!
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab nofoldenable
diff --git a/test/old/testdir/test_scroll_opt.vim b/test/old/testdir/test_scroll_opt.vim
index cb37b09707..50b0e13ba4 100644
--- a/test/old/testdir/test_scroll_opt.vim
+++ b/test/old/testdir/test_scroll_opt.vim
@@ -1031,10 +1031,10 @@ func Test_smoothscroll_page()
   call assert_equal(415, col('.'))
   exe "norm! \<C-D>"
   call assert_equal(520, winsaveview().skipcol)
-  call assert_equal(535, col('.'))
+  call assert_equal(615, col('.'))
   exe "norm! \<C-D>"
   call assert_equal(520, winsaveview().skipcol)
-  call assert_equal(735, col('.'))
+  call assert_equal(815, col('.'))
   exe "norm! \<C-D>"
   call assert_equal(520, winsaveview().skipcol)
   call assert_equal(895, col('.'))
@@ -1046,10 +1046,10 @@ func Test_smoothscroll_page()
   call assert_equal(495, col('.'))
   exe "norm! \<C-U>"
   call assert_equal(0, winsaveview().skipcol)
-  call assert_equal(375, col('.'))
+  call assert_equal(295, col('.'))
   exe "norm! \<C-U>"
   call assert_equal(0, winsaveview().skipcol)
-  call assert_equal(175, col('.'))
+  call assert_equal(95, col('.'))
   exe "norm! \<C-U>"
   call assert_equal(0, winsaveview().skipcol)
   call assert_equal(15, col('.'))