vim-patch:9.1.0258: half-page scrolling broke backward compatibility

Problem:  Support for 'smoothscroll' in (half-)page scrolling
          broke backward compatibility and can be made to work better.
          (after v9.1.215)
Solution: Restore the previous cursor and end-of-buffer behavior for
          half-page scrolling and improve 'smoothscroll' support.
          (Luuk van Baal)

https://github.com/vim/vim/commit/cb204e688e5c9d56a78b621ef27c35d91860cb09

5 files changed, 71 insertions, 30 deletions

diff --git a/test/functional/legacy/matchparen_spec.lua b/test/functional/legacy/matchparen_spec.lua
index db5a24e2e0..0a21efeb7c 100644
--- a/test/functional/legacy/matchparen_spec.lua
+++ b/test/functional/legacy/matchparen_spec.lua
@@ -19,7 +19,7 @@ describe('matchparen', function()
       call cursor(5, 1)
     ]])
 
-    feed('V<c-d><c-d>3j')
+    feed('V<c-d><c-d>')
     screen:expect([[
       {17:{}                             |
       {17:}}                             |
diff --git a/test/old/testdir/test_diffmode.vim b/test/old/testdir/test_diffmode.vim
index 3e7eabf8f5..67f6aaecbb 100644
--- a/test/old/testdir/test_diffmode.vim
+++ b/test/old/testdir/test_diffmode.vim
@@ -1664,8 +1664,7 @@ func Test_diff_scroll_many_filler()
   endfor
 
   set smoothscroll&
-  bwipe!
-  bwipe!
+  %bwipe!
 endfunc
 
 " This was trying to update diffs for a buffer being closed
diff --git a/test/old/testdir/test_edit.vim b/test/old/testdir/test_edit.vim
index 1bfe46c4a9..abd30074d5 100644
--- a/test/old/testdir/test_edit.vim
+++ b/test/old/testdir/test_edit.vim
@@ -1320,7 +1320,7 @@ func Test_edit_PAGEUP_PAGEDOWN()
   call feedkeys("A\<PageUp>\<esc>", 'tnix')
   call assert_equal([0, 10, 1, 0], getpos('.'))
   call feedkeys("A\<PageUp>\<esc>", 'tnix')
-  call assert_equal([0, 2, 11, 0], getpos('.'))
+  call assert_equal([0, 10, 11, 0], getpos('.'))
   " <S-Up> is the same as <PageUp>
   " <S-Down> is the same as <PageDown>
   call cursor(1, 1)
@@ -1343,7 +1343,7 @@ func Test_edit_PAGEUP_PAGEDOWN()
   call feedkeys("A\<S-Up>\<esc>", 'tnix')
   call assert_equal([0, 10, 1, 0], getpos('.'))
   call feedkeys("A\<S-Up>\<esc>", 'tnix')
-  call assert_equal([0, 2, 11, 0], getpos('.'))
+  call assert_equal([0, 10, 11, 0], getpos('.'))
   set nostartofline
   call cursor(30, 11)
   norm! zt
@@ -1356,7 +1356,7 @@ func Test_edit_PAGEUP_PAGEDOWN()
   call feedkeys("A\<PageUp>\<esc>", 'tnix')
   call assert_equal([0, 10, 11, 0], getpos('.'))
   call feedkeys("A\<PageUp>\<esc>", 'tnix')
-  call assert_equal([0, 2, 11, 0], getpos('.'))
+  call assert_equal([0, 10, 11, 0], getpos('.'))
   call cursor(1, 1)
   call feedkeys("A\<PageDown>\<esc>", 'tnix')
   call assert_equal([0, 9, 11, 0], getpos('.'))
@@ -1381,7 +1381,7 @@ func Test_edit_PAGEUP_PAGEDOWN()
   call feedkeys("A\<S-Up>\<esc>", 'tnix')
   call assert_equal([0, 10, 11, 0], getpos('.'))
   call feedkeys("A\<S-Up>\<esc>", 'tnix')
-  call assert_equal([0, 2, 11, 0], getpos('.'))
+  call assert_equal([0, 10, 11, 0], getpos('.'))
   call cursor(1, 1)
   call feedkeys("A\<S-Down>\<esc>", 'tnix')
   call assert_equal([0, 9, 11, 0], getpos('.'))
diff --git a/test/old/testdir/test_normal.vim b/test/old/testdir/test_normal.vim
index 26270fddd2..013d8959ca 100644
--- a/test/old/testdir/test_normal.vim
+++ b/test/old/testdir/test_normal.vim
@@ -1283,13 +1283,9 @@ func Test_vert_scroll_cmds()
   exe "normal \<C-D>"
   call assert_equal(46, line('.'))
   exe "normal \<C-U>"
-  call assert_equal(36, line('w0'))
-  call assert_equal(46, line('.'))
-  exe "normal \<C-U>"
-  call assert_equal(1,  line('w0'))
-  call assert_equal(40, line('.'))
+  call assert_equal(36, line('.'))
   exe "normal \<C-U>"
-  call assert_equal(30, line('.'))
+  call assert_equal(1, line('.'))
   exe "normal \<C-U>"
   call assert_equal(1, line('.'))
   set scroll&
@@ -1310,8 +1306,9 @@ func Test_vert_scroll_cmds()
   call assert_equal(50, line('.'))
   call assert_equal(100, line('w$'))
   normal z.
+  let lnum = winline()
   exe "normal \<C-D>"
-  call assert_equal(1, winline())
+  call assert_equal(lnum, winline())
   call assert_equal(50, line('.'))
   normal zt
   exe "normal \<C-D>"
@@ -3080,8 +3077,7 @@ func Test_normal42_halfpage()
   call assert_equal(2, &scroll)
   set scroll=5
   exe "norm! \<c-u>"
-  call assert_equal('3', getline('w0'))
-  call assert_equal('8', getline('.'))
+  call assert_equal('3', getline('.'))
   1
   set scrolloff=5
   exe "norm! \<c-d>"
@@ -3828,7 +3824,7 @@ func Test_normal_vert_scroll_longline()
   call assert_equal(1, winline())
   exe "normal \<C-B>"
   call assert_equal(10, line('.'))
-  call assert_equal(10, winline())
+  call assert_equal(4, winline())
   exe "normal \<C-B>\<C-B>"
   call assert_equal(5, line('.'))
   call assert_equal(5, winline())
diff --git a/test/old/testdir/test_scroll_opt.vim b/test/old/testdir/test_scroll_opt.vim
index 575ce0c6b5..4e551cdaad 100644
--- a/test/old/testdir/test_scroll_opt.vim
+++ b/test/old/testdir/test_scroll_opt.vim
@@ -552,14 +552,14 @@ func Test_smoothscroll_cursor_position()
   exe "normal \<C-Y>"
   call s:check_col_calc(1, 3, 41)
 
-   " Test "g0/g<Home>"
+  " Test "g0/g<Home>"
   exe "normal gg\<C-E>"
   norm $gkg0
-  call s:check_col_calc(1, 2, 21)
+  call s:check_col_calc(4, 1, 24)
 
   " Test moving the cursor behind the <<< display with 'virtualedit'
   set virtualedit=all
-  exe "normal \<C-E>3lgkh"
+  exe "normal \<C-E>gkh"
   call s:check_col_calc(3, 2, 23)
   set virtualedit&
 
@@ -1020,26 +1020,72 @@ func Test_smoothscroll_page()
   exe "norm! \<C-B>"
   call assert_equal(0, winsaveview().skipcol)
 
-  exe "norm! \<C-D>"
+  " Half-page scrolling does not go beyond end of buffer and moves the cursor.
+  exe "norm! 0\<C-D>"
   call assert_equal(200, winsaveview().skipcol)
+  call assert_equal(204, col('.'))
   exe "norm! \<C-D>"
   call assert_equal(400, winsaveview().skipcol)
+  call assert_equal(404, col('.'))
   exe "norm! \<C-D>"
-  call assert_equal(600, winsaveview().skipcol)
+  call assert_equal(520, winsaveview().skipcol)
+  call assert_equal(601, col('.'))
   exe "norm! \<C-D>"
-  call assert_equal(800, winsaveview().skipcol)
-  exe "norm! \<C-D>"
-  call assert_equal(880, winsaveview().skipcol)
+  call assert_equal(520, winsaveview().skipcol)
+  call assert_equal(801, col('.'))
   exe "norm! \<C-U>"
-  call assert_equal(680, winsaveview().skipcol)
+  call assert_equal(520, winsaveview().skipcol)
+  call assert_equal(601, col('.'))
   exe "norm! \<C-U>"
-  call assert_equal(480, winsaveview().skipcol)
-  exe "norm! \<C-U>"
-  call assert_equal(280, winsaveview().skipcol)
+  call assert_equal(400, winsaveview().skipcol)
+  call assert_equal(404, col('.'))
   exe "norm! \<C-U>"
-  call assert_equal(80, winsaveview().skipcol)
+  call assert_equal(200, winsaveview().skipcol)
+  call assert_equal(204, col('.'))
   exe "norm! \<C-U>"
   call assert_equal(0, winsaveview().skipcol)
+  call assert_equal(1, col('.'))
+
+  bwipe!
+endfunc
+
+func Test_smoothscroll_next_topline()
+  call NewWindow(10, 40)
+  setlocal smoothscroll
+  call setline(1, ['abcde '->repeat(150)]->repeat(2))
+
+  " Scrolling a screenline that causes the cursor to move to the next buffer
+  " line should not skip part of that line to bring the cursor into view.
+  exe "norm! 22\<C-E>"
+  call assert_equal(880, winsaveview().skipcol)
+  exe "norm! \<C-E>"
+  redraw
+  call assert_equal(0, winsaveview().skipcol)
+
+  " Cursor in correct place when not in the first screenline of a buffer line.
+  exe "norm! gg4gj20\<C-D>\<C-D>"
+  redraw
+  call assert_equal(2, line('w0'))
+
+  bwipe!
+endfunc
+
+func Test_smoothscroll_long_line_zb()
+  call NewWindow(10, 40)
+  call setline(1, 'abcde '->repeat(150))
+
+  " Also works without 'smoothscroll' when last line of buffer doesn't fit.
+  " Used to set topline to buffer line count plus one, causing an empty screen.
+  norm zb
+  redraw
+  call assert_equal(1, winsaveview().topline)
+
+  " Moving cursor to bottom works on line that doesn't fit with 'smoothscroll'.
+  " Skipcol was adjusted later for cursor being on not visible part of line.
+  setlocal smoothscroll
+  norm zb
+  redraw
+  call assert_equal(520, winsaveview().skipcol)
 
   bwipe!
 endfunc