vim-patch:8.0.0041

Problem:    When using Insert mode completion but not actually inserting
            anything an undo item is still created. (Tommy Allen)
Solution:   Do not call stop_arrow() when not inserting anything.

src/nvim/edit.c

@@ -2350,9 +2350,6 @@ void set_completion(colnr_T startcol, list_T *list)
   }
   ins_compl_clear();
 
-  if (stop_arrow() == FAIL)
-    return;
-
   compl_direction = FORWARD;
   if (startcol > curwin->w_cursor.col)
     startcol = curwin->w_cursor.col;
@@ -3263,14 +3260,19 @@ static bool ins_compl_prep(int c)
       } else {
         int prev_col = curwin->w_cursor.col;
 
-        /* put the cursor on the last char, for 'tw' formatting */
+        // put the cursor on the last char, for 'tw' formatting
-        if (prev_col > 0)
+        if (prev_col > 0) {
           dec_cursor();
-        if (stop_arrow() == OK)
+        }
+
+        if (!arrow_used && !ins_need_undo) {
           insertchar(NUL, 0, -1);
+        }
+
         if (prev_col > 0
-            && get_cursor_line_ptr()[curwin->w_cursor.col] != NUL)
+            && get_cursor_line_ptr()[curwin->w_cursor.col] != NUL) {
           inc_cursor();
+        }
       }
 
       // If the popup menu is displayed pressing CTRL-Y means accepting

test/functional/viml/completion_spec.lua

@@ -317,6 +317,62 @@ describe('completion', function()
     end)
   end)
 
+  describe('completeopt+=noinsert does not add blank undo items', function()
+    before_each(function()
+      source([[
+      function! TestComplete() abort
+        call complete(1, ['foo', 'bar'])
+        return ''
+      endfunction
+      ]])
+      execute('set completeopt+=noselect,noinsert')
+      execute('inoremap <right> <c-r>=TestComplete()<cr>')
+    end)
+
+    local tests = {
+      ['<up>, <down>, <cr>'] = {'<down><cr>', '<up><cr>'},
+      ['<c-n>, <c-p>, <c-y>'] = {'<c-n><c-y>', '<c-p><c-y>'},
+    }
+
+    for name, seq in pairs(tests) do
+      it('using ' .. name, function()
+        feed('iaaa<esc>')
+        feed('A<right>' .. seq[1] .. '<esc>')
+        feed('A<right><esc>A<right><esc>')
+        feed('A<cr>bbb<esc>')
+        feed('A<right>' .. seq[2] .. '<esc>')
+        feed('A<right><esc>A<right><esc>')
+        feed('A<cr>ccc<esc>')
+        feed('A<right>' .. seq[1] .. '<esc>')
+        feed('A<right><esc>A<right><esc>')
+
+        local expected = {
+          {'foo', 'bar', 'foo'},
+          {'foo', 'bar', 'ccc'},
+          {'foo', 'bar'},
+          {'foo', 'bbb'},
+          {'foo'},
+          {'aaa'},
+          {''},
+        }
+
+        for i = 1, #expected do
+          if i > 1 then
+            feed('u')
+          end
+          eq(expected[i], eval('getline(1, "$")'))
+        end
+
+        for i = #expected, 1, -1 do
+          if i < #expected then
+            feed('<c-r>')
+          end
+          eq(expected[i], eval('getline(1, "$")'))
+        end
+      end)
+    end
+  end)
+
   describe("refresh:always", function()
     before_each(function()
       source([[