Timer fails to properly update the screen

[markonm]

Vim version: 8.0.1449

" reproduce.vim
function! Timer() abort
  call timer_start(0, { _-> matchadd('Search', '.') })
  return ''
endfunction
nnoremap <expr> <c-j> Timer()

1. vim  --clean reproduce.vim
2. :so %
3. <c-j>
4. screen is not updated until the cursor is moved

This fails on linux TUI vim. On gVim it works properly. It also works properly on Windows in gVim and vim.

I think changes in redraw_after_callback from this commit are the cause.

[lacygoill]

I have the same issue.

I was adding/removing a match for a short period of time, with timers, every time I move the cursor to the next occurrence of a search pattern with n, to get a blinking effect. It worked until the patch v8.0.1449. Now, there's no blinking anymore, the match stays active for a few seconds, before disappearing.

As said by @xtal8 , the issue seems specific to Vim in the terminal (not gVim).

---

Current environment:

• vim --version: VIM - Vi IMproved 8.0 Included patches: 1-1464
• Operating system: Ubuntu 16.04.3 LTS
• Terminal emulator: rxvt-unicode v9.22
• Terminal multiplexer: tmux 2.3
• $TERM: screen-256color
• Shell: zsh 5.3.1

[markonm]

Fixed by acda04f. Thanks!