vim-patch:8.2.4626: Visual area not updated when removing sign in Visual mode (#17864)

Problem:    Visual area not fully updated when removing sign in Visual mode
            while scrolling.
Solution:   Adjust check for topline. (closes vim/vim#10017)
https://github.com/vim/vim/commit/abb6fbd14d985b9b36a4e336d6edaf9853888ac1

3 files changed, 55 insertions, 4 deletions

diff --git a/src/nvim/screen.c b/src/nvim/screen.c
index 5a10543559..41a129dba9 100644
--- a/src/nvim/screen.c
+++ b/src/nvim/screen.c
@@ -938,7 +938,7 @@ static void win_update(win_T *wp, DecorProviders *providers)
     if (mod_top != 0
         && wp->w_topline == mod_top
         && (!wp->w_lines[0].wl_valid
-            || wp->w_topline <= wp->w_lines[0].wl_lnum)) {
+            || wp->w_topline == wp->w_lines[0].wl_lnum)) {
       // w_topline is the first changed line and window is not scrolled,
       // the scrolling from changed lines will be done further down.
     } else if (wp->w_lines[0].wl_valid
diff --git a/src/nvim/testdir/test_display.vim b/src/nvim/testdir/test_display.vim
index 9f74d0a38a..094283a3a3 100644
--- a/src/nvim/testdir/test_display.vim
+++ b/src/nvim/testdir/test_display.vim
@@ -263,6 +263,27 @@ func Test_display_scroll_at_topline()
   call StopVimInTerminal(buf)
 endfunc
 
+func Test_display_scroll_update_visual()
+  CheckScreendump
+
+  let lines =<< trim END
+      set scrolloff=0
+      call setline(1, repeat(['foo'], 10))
+      call sign_define('foo', { 'text': '>' })
+      call sign_place(1, 'bar', 'foo', bufnr(), { 'lnum': 2 })
+      call sign_place(2, 'bar', 'foo', bufnr(), { 'lnum': 1 })
+      autocmd CursorMoved * if getcurpos()[1] == 2 | call sign_unplace('bar', { 'id': 1 }) | endif
+  END
+  call writefile(lines, 'XupdateVisual.vim')
+
+  let buf = RunVimInTerminal('-S XupdateVisual.vim', #{rows: 8, cols: 60})
+  call term_sendkeys(buf, "VG7kk")
+  call VerifyScreenDump(buf, 'Test_display_scroll_update_visual', {})
+
+  call StopVimInTerminal(buf)
+  call delete('XupdateVisual.vim')
+endfunc
+
 " Test for 'eob' (EndOfBuffer) item in 'fillchars'
 func Test_eob_fillchars()
   " default value (skipped)
diff --git a/test/functional/legacy/display_spec.lua b/test/functional/legacy/display_spec.lua
index 3fbbe96947..59ba170e33 100644
--- a/test/functional/legacy/display_spec.lua
+++ b/test/functional/legacy/display_spec.lua
@@ -3,15 +3,15 @@ local helpers = require('test.functional.helpers')(after_each)
 local Screen = require('test.functional.ui.screen')
 local clear = helpers.clear
 local poke_eventloop = helpers.poke_eventloop
+local exec = helpers.exec
 local feed = helpers.feed
 local feed_command = helpers.feed_command
 
 describe('display', function()
-  local screen
+  before_each(clear)
 
   it('scroll when modified at topline', function()
-    clear()
-    screen = Screen.new(20, 4)
+    local screen = Screen.new(20, 4)
     screen:attach()
     screen:set_default_attr_ids({
       [1] = {bold = true},
@@ -27,5 +27,35 @@ describe('display', function()
       {1:-- INSERT --}        |
     ]])
   end)
+
+  it('scrolling when modified at topline in Visual mode', function()
+    local screen = Screen.new(60, 8)
+    screen:attach()
+    screen:set_default_attr_ids({
+      [1] = {bold = true},  -- ModeMsg
+      [2] = {background = Screen.colors.LightGrey},  -- Visual
+      [3] = {background = Screen.colors.Grey, foreground = Screen.colors.DarkBlue},  -- SignColumn
+    })
+
+    exec([[
+      set scrolloff=0
+      call setline(1, repeat(['foo'], 10))
+      call sign_define('foo', { 'text': '>' })
+      call sign_place(1, 'bar', 'foo', bufnr(), { 'lnum': 2 })
+      call sign_place(2, 'bar', 'foo', bufnr(), { 'lnum': 1 })
+      autocmd CursorMoved * if getcurpos()[1] == 2 | call sign_unplace('bar', { 'id': 1 }) | endif
+    ]])
+    feed('VG7kk')
+    screen:expect([[
+      {3:  }^f{2:oo}                                                       |
+      {3:  }foo                                                       |
+      {3:  }foo                                                       |
+      {3:  }foo                                                       |
+      {3:  }foo                                                       |
+      {3:  }foo                                                       |
+      {3:  }foo                                                       |
+      {1:-- VISUAL LINE --}                                           |
+    ]])
+  end)
 end)