vim-patch:9.1.0215: Half-page scrolling does not support smooth-scrolling

Problem:  Page-wise scrolling with Ctrl-D/Ctrl-U implements
          it's own logic to change the topline and cursor.
          More logic than necessary for scrolling with Ctrl-F/Ctrl-B
          was removed in patch 9.1.0211.
Solution: Re-use the logic from Ctrl-E/Ctrl-Y/Ctrl-F/Ctrl-B while
          staying backward compatible as much as possible.
          Restore some of the logic that determined how many lines will
          be scrolled (Luuk van Baal)

https://github.com/vim/vim/commit/5a2e3ec9ac72b6e644fea4ebba7e632498296e2f

4 files changed, 59 insertions, 30 deletions

diff --git a/test/functional/legacy/matchparen_spec.lua b/test/functional/legacy/matchparen_spec.lua
index 7b3f7bd424..adbf15d2e3 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>')
+    feed('V<c-d><c-d>3j')
     screen:expect([[
       {17:{}                             |
       {17:}}                             |
diff --git a/test/old/testdir/test_edit.vim b/test/old/testdir/test_edit.vim
index 2d4314a276..ba084442d1 100644
--- a/test/old/testdir/test_edit.vim
+++ b/test/old/testdir/test_edit.vim
@@ -1312,15 +1312,15 @@ func Test_edit_PAGEUP_PAGEDOWN()
   call feedkeys("i\<PageDown>\<esc>", 'tnix')
   call assert_equal([0, 30, 1, 0], getpos('.'))
   call feedkeys("A\<PageUp>\<esc>", 'tnix')
-  call assert_equal([0, 30, 1, 0], getpos('.'))
+  call assert_equal([0, 29, 1, 0], getpos('.'))
   call feedkeys("A\<PageUp>\<esc>", 'tnix')
-  call assert_equal([0, 23, 1, 0], getpos('.'))
+  call assert_equal([0, 21, 1, 0], getpos('.'))
   call feedkeys("A\<PageUp>\<esc>", 'tnix')
-  call assert_equal([0, 15, 1, 0], getpos('.'))
+  call assert_equal([0, 13, 1, 0], getpos('.'))
   call feedkeys("A\<PageUp>\<esc>", 'tnix')
   call assert_equal([0, 10, 1, 0], getpos('.'))
   call feedkeys("A\<PageUp>\<esc>", 'tnix')
-  call assert_equal([0, 10, 11, 0], getpos('.'))
+  call assert_equal([0, 2, 11, 0], getpos('.'))
   " <S-Up> is the same as <PageUp>
   " <S-Down> is the same as <PageDown>
   call cursor(1, 1)
@@ -1335,28 +1335,28 @@ func Test_edit_PAGEUP_PAGEDOWN()
   call feedkeys("i\<S-Down>\<esc>", 'tnix')
   call assert_equal([0, 30, 1, 0], getpos('.'))
   call feedkeys("A\<S-Up>\<esc>", 'tnix')
-  call assert_equal([0, 30, 1, 0], getpos('.'))
+  call assert_equal([0, 29, 1, 0], getpos('.'))
   call feedkeys("A\<S-Up>\<esc>", 'tnix')
-  call assert_equal([0, 23, 1, 0], getpos('.'))
+  call assert_equal([0, 21, 1, 0], getpos('.'))
   call feedkeys("A\<S-Up>\<esc>", 'tnix')
-  call assert_equal([0, 15, 1, 0], getpos('.'))
+  call assert_equal([0, 13, 1, 0], getpos('.'))
   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, 10, 11, 0], getpos('.'))
+  call assert_equal([0, 2, 11, 0], getpos('.'))
   set nostartofline
   call cursor(30, 11)
   norm! zt
   call feedkeys("A\<PageUp>\<esc>", 'tnix')
-  call assert_equal([0, 30, 11, 0], getpos('.'))
+  call assert_equal([0, 29, 11, 0], getpos('.'))
   call feedkeys("A\<PageUp>\<esc>", 'tnix')
-  call assert_equal([0, 23, 11, 0], getpos('.'))
+  call assert_equal([0, 21, 11, 0], getpos('.'))
   call feedkeys("A\<PageUp>\<esc>", 'tnix')
-  call assert_equal([0, 15, 11, 0], getpos('.'))
+  call assert_equal([0, 13, 11, 0], getpos('.'))
   call feedkeys("A\<PageUp>\<esc>", 'tnix')
   call assert_equal([0, 10, 11, 0], getpos('.'))
   call feedkeys("A\<PageUp>\<esc>", 'tnix')
-  call assert_equal([0, 10, 11, 0], getpos('.'))
+  call assert_equal([0, 2, 11, 0], getpos('.'))
   call cursor(1, 1)
   call feedkeys("A\<PageDown>\<esc>", 'tnix')
   call assert_equal([0, 9, 11, 0], getpos('.'))
@@ -1373,15 +1373,15 @@ func Test_edit_PAGEUP_PAGEDOWN()
   call cursor(30, 11)
   norm! zt
   call feedkeys("A\<S-Up>\<esc>", 'tnix')
-  call assert_equal([0, 30, 11, 0], getpos('.'))
+  call assert_equal([0, 29, 11, 0], getpos('.'))
   call feedkeys("A\<S-Up>\<esc>", 'tnix')
-  call assert_equal([0, 23, 11, 0], getpos('.'))
+  call assert_equal([0, 21, 11, 0], getpos('.'))
   call feedkeys("A\<S-Up>\<esc>", 'tnix')
-  call assert_equal([0, 15, 11, 0], getpos('.'))
+  call assert_equal([0, 13, 11, 0], getpos('.'))
   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, 10, 11, 0], getpos('.'))
+  call assert_equal([0, 2, 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 644a632413..937f18aa69 100644
--- a/test/old/testdir/test_normal.vim
+++ b/test/old/testdir/test_normal.vim
@@ -1283,9 +1283,13 @@ func Test_vert_scroll_cmds()
   exe "normal \<C-D>"
   call assert_equal(46, line('.'))
   exe "normal \<C-U>"
-  call assert_equal(36, line('.'))
+  call assert_equal(36, line('w0'))
+  call assert_equal(46, line('.'))
   exe "normal \<C-U>"
-  call assert_equal(10, line('.'))
+  call assert_equal(1,  line('w0'))
+  call assert_equal(40, line('.'))
+  exe "normal \<C-U>"
+  call assert_equal(30, line('.'))
   exe "normal \<C-U>"
   call assert_equal(1, line('.'))
   set scroll&
@@ -1306,9 +1310,8 @@ 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(lnum, winline())
+  call assert_equal(1, winline())
   call assert_equal(50, line('.'))
   normal zt
   exe "normal \<C-D>"
@@ -3077,7 +3080,8 @@ func Test_normal42_halfpage()
   call assert_equal(2, &scroll)
   set scroll=5
   exe "norm! \<c-u>"
-  call assert_equal('3', getline('.'))
+  call assert_equal('3', getline('w0'))
+  call assert_equal('8', getline('.'))
   1
   set scrolloff=5
   exe "norm! \<c-d>"
@@ -3823,11 +3827,11 @@ func Test_normal_vert_scroll_longline()
   call assert_equal(11, line('.'))
   call assert_equal(1, winline())
   exe "normal \<C-B>"
-  call assert_equal(11, line('.'))
-  call assert_equal(9, winline())
+  call assert_equal(10, line('.'))
+  call assert_equal(10, winline())
   exe "normal \<C-B>\<C-B>"
   call assert_equal(5, line('.'))
-  call assert_equal(1, winline())
+  call assert_equal(5, winline())
 
   bwipe!
 endfunc
@@ -4196,12 +4200,16 @@ func Test_single_line_scroll()
   norm! {
   call assert_equal([0, 1, 1, 0], getpos('.'))
 
-  " Ctrl-B scrolls up with hidden "above" virtual text.
+  " Ctrl-B/Ctrl-U scroll up with hidden "above" virtual text.
   set smoothscroll
   exe "normal \<C-E>"
   call assert_notequal(0, winsaveview().skipcol)
   exe "normal \<C-B>"
   call assert_equal(0, winsaveview().skipcol)
+  exe "normal \<C-E>"
+  call assert_notequal(0, winsaveview().skipcol)
+  exe "normal \<C-U>"
+  call assert_equal(0, winsaveview().skipcol)
 
   set smoothscroll&
   bw!
diff --git a/test/old/testdir/test_scroll_opt.vim b/test/old/testdir/test_scroll_opt.vim
index ebfed77214..fbc714d9cc 100644
--- a/test/old/testdir/test_scroll_opt.vim
+++ b/test/old/testdir/test_scroll_opt.vim
@@ -1008,18 +1008,39 @@ func Test_smoothscroll_page()
   call setline(1, 'abcde '->repeat(150))
 
   exe "norm! \<C-F>"
-  call assert_equal(320, winsaveview().skipcol)
+  call assert_equal(400, winsaveview().skipcol)
   exe "norm! \<C-F>"
-  call assert_equal(640, winsaveview().skipcol)
+  call assert_equal(800, winsaveview().skipcol)
   exe "norm! \<C-F>"
   call assert_equal(880, winsaveview().skipcol)
   exe "norm! \<C-B>"
-  call assert_equal(560, winsaveview().skipcol)
+  call assert_equal(480, winsaveview().skipcol)
   exe "norm! \<C-B>"
-  call assert_equal(240, winsaveview().skipcol)
+  call assert_equal(80, winsaveview().skipcol)
   exe "norm! \<C-B>"
   call assert_equal(0, winsaveview().skipcol)
 
+  exe "norm! \<C-D>"
+  call assert_equal(200, winsaveview().skipcol)
+  exe "norm! \<C-D>"
+  call assert_equal(400, winsaveview().skipcol)
+  exe "norm! \<C-D>"
+  call assert_equal(600, winsaveview().skipcol)
+  exe "norm! \<C-D>"
+  call assert_equal(800, winsaveview().skipcol)
+  exe "norm! \<C-D>"
+  call assert_equal(880, winsaveview().skipcol)
+  exe "norm! \<C-U>"
+  call assert_equal(680, winsaveview().skipcol)
+  exe "norm! \<C-U>"
+  call assert_equal(480, winsaveview().skipcol)
+  exe "norm! \<C-U>"
+  call assert_equal(280, winsaveview().skipcol)
+  exe "norm! \<C-U>"
+  call assert_equal(80, winsaveview().skipcol)
+  exe "norm! \<C-U>"
+  call assert_equal(0, winsaveview().skipcol)
+
   set smoothscroll&
 endfunc