vim-patch:9.0.0645: CTRL-Y does not stop at line 1

Problem:    CTRL-Y does not stop at line 1. (John Marriott)
Solution:   Stop at line 1 when 'smoothscroll' is not set. (closes vim/vim#11261)

8df9748edb

Co-authored-by: Bram Moolenaar <Bram@vim.org>

src/nvim/move.c

@@ -1109,10 +1109,12 @@ bool scrolldown(long line_count, int byfold)
       curwin->w_topfill++;
       done++;
     } else {
-      if (curwin->w_topline == 1 && curwin->w_skipcol < width1) {
+      // break when at the very top
+      if (curwin->w_topline == 1 && (!curwin->w_p_sms || curwin->w_skipcol < width1)) {
         break;
       }
       if (curwin->w_p_wrap && curwin->w_p_sms && curwin->w_skipcol >= width1) {
+        // scroll a screen line down
         if (curwin->w_skipcol >= width1 + width2) {
           curwin->w_skipcol -= width2;
         } else {
@@ -1121,6 +1123,7 @@ bool scrolldown(long line_count, int byfold)
         redraw_later(curwin, UPD_NOT_VALID);
         done++;
       } else {
+        // scroll a text line down
         curwin->w_topline--;
         curwin->w_skipcol = 0;
         curwin->w_topfill = 0;

test/functional/legacy/scroll_opt_spec.lua

@@ -14,6 +14,19 @@ describe('smoothscroll', function()
     screen:attach()
   end)
 
+  -- oldtest: Test_CtrlE_CtrlY_stop_at_end()
+  it('disabled does not break <C-E> and <C-Y> stop at end', function()
+    exec([[
+      enew
+      call setline(1, ['one', 'two'])
+      set number
+    ]])
+    feed('<C-Y>')
+    screen:expect({any = "  1 ^one"})
+    feed('<C-E><C-E><C-E>')
+    screen:expect({any = "  2 ^two"})
+  end)
+
   -- oldtest: Test_smoothscroll_CtrlE_CtrlY()
   it('works with <C-E> and <C-E>', function()
     exec([[

test/old/testdir/test_scroll_opt.vim

@@ -54,6 +54,19 @@ func Test_scolloff_even_line_count()
    bwipe!
 endfunc
 
+func Test_CtrlE_CtrlY_stop_at_end()
+  enew
+  call setline(1, ['one', 'two'])
+  set number
+  exe "normal \<C-Y>"
+  call assert_equal(["  1 one   "], ScreenLines(1, 10))
+  exe "normal \<C-E>\<C-E>\<C-E>"
+  call assert_equal(["  2 two   "], ScreenLines(1, 10))
+
+  bwipe!
+  set nonumber
+endfunc
+
 func Test_smoothscroll_CtrlE_CtrlY()
   CheckScreendump