vim-patch:9.0.0608: with spelling, deleting a full stop does not update next line

Problem:    With spell checking, deleting a full stop at the end of a line
            does not update SpellCap at the start of the next line.
Solution:   Update the next line when characters have been deleted.  Also when
            using undo.

https://github.com/vim/vim/commit/26f09ea54b2c60abf21df42c60bdfc60eca17b0d

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

5 files changed, 46 insertions, 8 deletions

diff --git a/src/nvim/change.c b/src/nvim/change.c
index f4969d0ca9..ebbb0d4db6 100644
--- a/src/nvim/change.c
+++ b/src/nvim/change.c
@@ -43,6 +43,7 @@
 #include "nvim/plines.h"
 #include "nvim/pos.h"
 #include "nvim/search.h"
+#include "nvim/spell.h"
 #include "nvim/state.h"
 #include "nvim/strings.h"
 #include "nvim/textformat.h"
@@ -393,6 +394,12 @@ void changed_bytes(linenr_T lnum, colnr_T col)
 {
   changedOneline(curbuf, lnum);
   changed_common(lnum, col, lnum + 1, 0);
+  // When text has been changed at the end of the line, possibly the start of
+  // the next line may have SpellCap that should be removed or it needs to be
+  // displayed.  Schedule the next line for redrawing just in case.
+  if (spell_check_window(curwin) && lnum < curbuf->b_ml.ml_line_count) {
+    redrawWinline(curwin, lnum + 1);
+  }
   // notify any channels that are watching
   buf_updates_send_changes(curbuf, lnum, 1, 1);
 
diff --git a/src/nvim/edit.c b/src/nvim/edit.c
index 612a1a1bda..c0f094453d 100644
--- a/src/nvim/edit.c
+++ b/src/nvim/edit.c
@@ -3395,14 +3395,6 @@ static bool ins_esc(long *count, int cmdchar, bool nomove)
 
   check_spell_redraw();
 
-  // When text has been changed in this line, possibly the start of the next
-  // line may have SpellCap that should be removed or it needs to be
-  // displayed.  Schedule the next line for redrawing just in case.
-  if (spell_check_window(curwin)
-      && curwin->w_cursor.lnum < curbuf->b_ml.ml_line_count) {
-    redrawWinline(curwin, curwin->w_cursor.lnum + 1);
-  }
-
   int temp = curwin->w_cursor.col;
   if (disabled_redraw) {
     RedrawingDisabled--;
diff --git a/src/nvim/undo.c b/src/nvim/undo.c
index 00a3922a5b..1eb73d85d7 100644
--- a/src/nvim/undo.c
+++ b/src/nvim/undo.c
@@ -120,6 +120,7 @@
 #include "nvim/path.h"
 #include "nvim/pos.h"
 #include "nvim/sha256.h"
+#include "nvim/spell.h"
 #include "nvim/state.h"
 #include "nvim/strings.h"
 #include "nvim/types.h"
@@ -2372,6 +2373,12 @@ static void u_undoredo(int undo, bool do_buf_event)
     }
 
     changed_lines(top + 1, 0, bot, newsize - oldsize, do_buf_event);
+    // When text has been changed, possibly the start of the next line
+    // may have SpellCap that should be removed or it needs to be
+    // displayed.  Schedule the next line for redrawing just in case.
+    if (spell_check_window(curwin) && bot <= curbuf->b_ml.ml_line_count) {
+      redrawWinline(curwin, bot);
+    }
 
     // Set the '[ mark.
     if (top + 1 < curbuf->b_op_start.lnum) {
diff --git a/test/functional/ui/spell_spec.lua b/test/functional/ui/spell_spec.lua
index 5cfb85e431..800043b169 100644
--- a/test/functional/ui/spell_spec.lua
+++ b/test/functional/ui/spell_spec.lua
@@ -115,6 +115,30 @@ describe("'spell'", function()
       {0:~                                                                               }|
                                                                                       |
     ]])
+    -- Deleting a full stop removes missing Cap in next line
+    feed('5Gddk$x')
+    screen:expect([[
+         This line has a {1:sepll} error. {2:and} missing caps and trailing spaces.           |
+      {2:another} missing cap here.                                                       |
+      Not                                                                             |
+      and her^e                                                                        |
+      and here.                                                                       |
+      {0:~                                                                               }|
+      {0:~                                                                               }|
+                                                                                      |
+    ]])
+    -- Undo also updates the next line (go to command line to remove message)
+    feed('u:<Esc>')
+    screen:expect([[
+         This line has a {1:sepll} error. {2:and} missing caps and trailing spaces.           |
+      {2:another} missing cap here.                                                       |
+      Not                                                                             |
+      and here^.                                                                       |
+      {2:and} here.                                                                       |
+      {0:~                                                                               }|
+      {0:~                                                                               }|
+                                                                                      |
+    ]])
   end)
 
   it('extmarks, "noplainbuffer" and syntax #20385 #23398', function()
diff --git a/test/old/testdir/test_spell.vim b/test/old/testdir/test_spell.vim
index 15c47881a9..c959e199d9 100644
--- a/test/old/testdir/test_spell.vim
+++ b/test/old/testdir/test_spell.vim
@@ -1018,6 +1018,14 @@ func Test_spell_screendump_spellcap()
   call term_sendkeys(buf, "3GANot\<Esc>")
   call VerifyScreenDump(buf, 'Test_spell_3', {})
 
+  " Deleting a full stop removes missing Cap in next line
+  call term_sendkeys(buf, "5Gddk$x")
+  call VerifyScreenDump(buf, 'Test_spell_4', {})
+
+  " Undo also updates the next line (go to command line to remove message)
+  call term_sendkeys(buf, "u:\<Esc>")
+  call VerifyScreenDump(buf, 'Test_spell_5', {})
+
   " clean up
   call StopVimInTerminal(buf)
   call delete('XtestSpellCap')