vim-patch:8.1.1055: CTRL-G U in Insert mode doesn't work for shift-Left

Problem:    CTRL-G U in Insert mode doesn't work to avoid splitting the undo
            sequence for shift-left and shift-right.
Solution:   Also check dont_sync_undo for shifted cursor keys. (Christian
            Brabandt)
75bf3d22f4

src/nvim/edit.c

@@ -276,7 +276,7 @@ static int ins_need_undo;               /* call u_save() before inserting a
 static bool did_add_space = false;      // auto_format() added an extra space
                                         // under the cursor
 static TriState dont_sync_undo = kFalse;  // CTRL-G U prevents syncing undo
-                                          // for the next left/right cursor
+                                          // for the next left/right cursor key
 
 static linenr_T o_lnum = 0;
 
@@ -1037,7 +1037,7 @@ check_pum:
     if (mod_mask & (MOD_MASK_SHIFT|MOD_MASK_CTRL)) {
       ins_s_left();
     } else {
-      ins_left(dont_sync_undo == kFalse);
+      ins_left();
     }
     break;
 
@@ -1050,7 +1050,7 @@ check_pum:
     if (mod_mask & (MOD_MASK_SHIFT|MOD_MASK_CTRL)) {
       ins_s_right();
     } else {
-      ins_right(dont_sync_undo == kFalse);
+      ins_right();
     }
     break;
 
@@ -8103,9 +8103,10 @@ static void ins_mousescroll(int dir)
 
 
 
-static void ins_left(bool end_change)
+static void ins_left(void)
 {
   pos_T tpos;
+  const bool end_change = dont_sync_undo == kFalse;  // end undoable change
 
   if ((fdo_flags & FDO_HOR) && KeyTyped)
     foldOpenCursor();
@@ -8167,23 +8168,31 @@ static void ins_end(int c)
 
 static void ins_s_left(void)
 {
-  if ((fdo_flags & FDO_HOR) && KeyTyped)
+  const bool end_change = dont_sync_undo == kFalse;  // end undoable change
+  if ((fdo_flags & FDO_HOR) && KeyTyped) {
     foldOpenCursor();
+  }
   undisplay_dollar();
   if (curwin->w_cursor.lnum > 1 || curwin->w_cursor.col > 0) {
-    start_arrow(&curwin->w_cursor);
+    start_arrow_with_change(&curwin->w_cursor, end_change);
+    if (!end_change) {
+      AppendCharToRedobuff(K_S_LEFT);
+    }
     (void)bck_word(1L, false, false);
     curwin->w_set_curswant = true;
   } else {
     vim_beep(BO_CRSR);
   }
+  dont_sync_undo = kFalse;
 }
 
 /// @param end_change      end undoable change
-static void ins_right(bool end_change)
+static void ins_right(void)
 {
-  if ((fdo_flags & FDO_HOR) && KeyTyped)
+  const bool end_change = dont_sync_undo == kFalse;  // end undoable change
+  if ((fdo_flags & FDO_HOR) && KeyTyped) {
     foldOpenCursor();
+  }
   undisplay_dollar();
   if (gchar_cursor() != NUL || virtual_active()) {
     start_arrow_with_change(&curwin->w_cursor, end_change);
@@ -8220,17 +8229,23 @@ static void ins_right(bool end_change)
 
 static void ins_s_right(void)
 {
-  if ((fdo_flags & FDO_HOR) && KeyTyped)
+  const bool end_change = dont_sync_undo == kFalse;  // end undoable change
+  if ((fdo_flags & FDO_HOR) && KeyTyped) {
     foldOpenCursor();
+  }
   undisplay_dollar();
   if (curwin->w_cursor.lnum < curbuf->b_ml.ml_line_count
       || gchar_cursor() != NUL) {
-    start_arrow(&curwin->w_cursor);
+    start_arrow_with_change(&curwin->w_cursor, end_change);
+    if (!end_change) {
+      AppendCharToRedobuff(K_S_RIGHT);
+    }
     (void)fwd_word(1L, false, 0);
     curwin->w_set_curswant = true;
   } else {
     vim_beep(BO_CRSR);
   }
+  dont_sync_undo = kFalse;
 }
 
 static void

src/nvim/testdir/test_mapping.vim

@@ -187,9 +187,32 @@ func Test_map_cursor()
   imapclear
 endfunc
 
+func Test_map_cursor_ctrl_gU()
+  " <c-g>U<cursor> works only within a single line
+  nnoremap c<* *Ncgn<C-r>"<C-G>U<S-Left>
+  call setline(1, ['foo', 'foobar', '', 'foo'])
+  call cursor(1,2)
+  call feedkeys("c<*PREFIX\<esc>.", 'xt')
+  call assert_equal(['PREFIXfoo', 'foobar', '', 'PREFIXfoo'], getline(1,'$'))
+  " break undo manually
+  set ul=1000
+  exe ":norm! uu"
+  call assert_equal(['foo', 'foobar', '', 'foo'], getline(1,'$'))
+
+  " Test that it does not work if the cursor moves to the previous line
+  " 2 times <S-Left> move to the previous line
+  nnoremap c<* *Ncgn<C-r>"<C-G>U<S-Left><C-G>U<S-Left>
+  call setline(1, ['', ' foo', 'foobar', '', 'foo'])
+  call cursor(2,3)
+  call feedkeys("c<*PREFIX\<esc>.", 'xt')
+  call assert_equal(['PREFIXPREFIX', ' foo', 'foobar', '', 'foo'], getline(1,'$'))
+  nmapclear
+endfunc
+
+
 " This isn't actually testing a mapping, but similar use of CTRL-G U as above.
 func Test_break_undo()
-  :set whichwrap=<,>,[,]
+  set whichwrap=<,>,[,]
   call feedkeys("G4o2k", "xt")
   exe ":norm! iTest3: text with a (parenthesis here\<C-G>U\<Right>new line here\<esc>\<up>\<up>."
   call assert_equal('new line here', getline(line('$') - 3))