ModeChanged event is constantly triggered till 100% cpu uses with scheduled callback function

[shadmansaleh]

Describe the bug

If callback function of a ModeChanged autocmd schedules some operations with vim.schedule ModeChaged event constantly gets triggered switching between mods 'n' and 'no' when user switches to operator pending mode. As a result the callback gets called again and again until nvim saturates the cpu.
,

Steps to reproduce

file minimal_init.lua

local s = 0
local t = 0
vim.api.nvim_create_autocmd('ModeChanged', {
  callback = function ()
    s = s + 1
    print('callback scheduled', s)
    vim.schedule(function ()
      t = t + 1
      print('callback triggered', t)
    end)
  end,
})

Open neovim with the minimal config

nvim --clean -u minimal_init.lua

go into operator pending mode by pressing d for example.

Expected behavior

The ModeChanged event should get triggerd only once and the callback should be ran only once.

Neovim version (nvim -v)

0.9.0 commit 264fb69

Vim (not Nvim) behaves the same?

no. vim doesn't really have vim.schedule

Operating system/version

Arch Linux

Terminal name/version

kitty

$TERM environment variable

xterm-kitty

Installation

build from repo

[akai54]

Hi,
I would really like to work on this issue, but I don't know really know where to start, neither how,
if anyone can point at least the files I should be checking for this, it would be awesome.

[MunifTanjim]

Relevant Codes:

• neovim/src/nvim/normal.c

  Lines 961 to 962 in bf0ac4f

  	finish_op = false;
  	may_trigger_modechanged();