vim-patch:8.2.3952: first line not redrawn when adding lines to an empty buffer

Problem:    First line not redrawn when adding lines to an empty buffer.
Solution:   Adjust the argument to appended_lines(). (closes vim/vim#9439,
            closes vim/vim#9438)
https://github.com/vim/vim/commit/1fa3de1ce806ba18ebcc00c6d9a0678a84735463

3 files changed, 111 insertions, 10 deletions

diff --git a/src/nvim/ex_cmds.c b/src/nvim/ex_cmds.c
index cc5ab1b554..95390b1a70 100644
--- a/src/nvim/ex_cmds.c
+++ b/src/nvim/ex_cmds.c
@@ -3006,7 +3006,12 @@ void ex_append(exarg_T *eap)
 
     did_undo = true;
     ml_append(lnum, theline, (colnr_T)0, false);
-    appended_lines_mark(lnum + (empty ? 1 : 0), 1L);
+    if (empty) {
+      // there are no marks below the inserted lines
+      appended_lines(lnum, 1L);
+    } else {
+      appended_lines_mark(lnum, 1L);
+    }
 
     xfree(theline);
     ++lnum;
diff --git a/src/nvim/testdir/test_excmd.vim b/src/nvim/testdir/test_excmd.vim
index 2d01cbba83..1c053c824f 100644
--- a/src/nvim/testdir/test_excmd.vim
+++ b/src/nvim/testdir/test_excmd.vim
@@ -1,6 +1,8 @@
 " Tests for various Ex commands.
 
 source check.vim
+source shared.vim
+source term_util.vim
 
 func Test_ex_delete()
   new
@@ -122,6 +124,27 @@ func Test_append_cmd()
   close!
 endfunc
 
+func Test_append_cmd_empty_buf()
+  CheckRunVimInTerminal
+  let lines =<< trim END
+    func Timer(timer)
+      append
+    aaaaa
+    bbbbb
+    .
+    endfunc
+    call timer_start(10, 'Timer')
+  END
+  call writefile(lines, 'Xtest_append_cmd_empty_buf')
+  let buf = RunVimInTerminal('-S Xtest_append_cmd_empty_buf', {'rows': 6})
+  call WaitForAssert({-> assert_equal('bbbbb', term_getline(buf, 2))})
+  call WaitForAssert({-> assert_equal('aaaaa', term_getline(buf, 1))})
+
+  " clean up
+  call StopVimInTerminal(buf)
+  call delete('Xtest_append_cmd_empty_buf')
+endfunc
+
 " Test for the :insert command
 func Test_insert_cmd()
   set noautoindent " test assumes noautoindent, but it's on by default in Nvim
@@ -151,6 +174,27 @@ func Test_insert_cmd()
   close!
 endfunc
 
+func Test_insert_cmd_empty_buf()
+  CheckRunVimInTerminal
+  let lines =<< trim END
+    func Timer(timer)
+      insert
+    aaaaa
+    bbbbb
+    .
+    endfunc
+    call timer_start(10, 'Timer')
+  END
+  call writefile(lines, 'Xtest_insert_cmd_empty_buf')
+  let buf = RunVimInTerminal('-S Xtest_insert_cmd_empty_buf', {'rows': 6})
+  call WaitForAssert({-> assert_equal('bbbbb', term_getline(buf, 2))})
+  call WaitForAssert({-> assert_equal('aaaaa', term_getline(buf, 1))})
+
+  " clean up
+  call StopVimInTerminal(buf)
+  call delete('Xtest_insert_cmd_empty_buf')
+endfunc
+
 " Test for the :change command
 func Test_change_cmd()
   set noautoindent " test assumes noautoindent, but it's on by default in Nvim
diff --git a/test/functional/ex_cmds/append_spec.lua b/test/functional/ex_cmds/append_spec.lua
index 0a4d701794..fadb5c9b42 100644
--- a/test/functional/ex_cmds/append_spec.lua
+++ b/test/functional/ex_cmds/append_spec.lua
@@ -1,23 +1,26 @@
 local helpers = require('test.functional.helpers')(after_each)
 
 local eq = helpers.eq
+local dedent = helpers.dedent
+local exec = helpers.exec
 local feed = helpers.feed
 local clear = helpers.clear
 local funcs = helpers.funcs
 local command = helpers.command
 local curbufmeths = helpers.curbufmeths
-
-before_each(function()
-  clear()
-  curbufmeths.set_lines(0, 1, true, { 'foo', 'bar', 'baz' })
-end)
-
-local buffer_contents = function()
-  return curbufmeths.get_lines(0, -1, false)
-end
+local Screen = require('test.functional.ui.screen')
 
 local cmdtest = function(cmd, prep, ret1)
   describe(':' .. cmd, function()
+    before_each(function()
+      clear()
+      curbufmeths.set_lines(0, 1, true, { 'foo', 'bar', 'baz' })
+    end)
+
+    local buffer_contents = function()
+      return curbufmeths.get_lines(0, -1, false)
+    end
+
     it(cmd .. 's' .. prep .. ' the current line by default', function()
       command(cmd .. '\nabc\ndef\n')
       eq(ret1, buffer_contents())
@@ -52,3 +55,52 @@ end
 cmdtest('insert', ' before', { 'abc', 'def', 'foo', 'bar', 'baz' })
 cmdtest('append', ' after', { 'foo', 'abc', 'def', 'bar', 'baz' })
 cmdtest('change', '', { 'abc', 'def', 'bar', 'baz' })
+
+describe('the first line is redrawn correctly after inserting text in an empty buffer', function()
+  local screen
+  before_each(function()
+    clear()
+    screen = Screen.new(20, 8)
+    screen:set_default_attr_ids({
+      [1] = {bold = true, foreground = Screen.colors.Blue},
+      [2] = {bold = true, reverse = true},
+    })
+    screen:attach()
+  end)
+
+  it('using :append', function()
+    exec(dedent([[
+      append
+      aaaaa
+      bbbbb
+      .]]))
+    screen:expect([[
+      aaaaa               |
+      ^bbbbb               |
+      {1:~                   }|
+      {1:~                   }|
+      {1:~                   }|
+      {1:~                   }|
+      {1:~                   }|
+                          |
+    ]])
+  end)
+
+  it('using :insert', function()
+    exec(dedent([[
+      insert
+      aaaaa
+      bbbbb
+      .]]))
+    screen:expect([[
+      aaaaa               |
+      ^bbbbb               |
+      {1:~                   }|
+      {1:~                   }|
+      {1:~                   }|
+      {1:~                   }|
+      {1:~                   }|
+                          |
+    ]])
+  end)
+end)