Hangs with neovim and coc.nvim

[vn-ki]

Hangs when I press enter.

The following is visible when I force quit nvim and reopen using swp file.

pumvisible() ? "\," : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\      pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\p      umvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pu      mvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pum      visible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumv      isible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvi      sible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvis      ible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisi      ble() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisib      le() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisibl      e() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible      () ? "\" : "\\pumvisible() ? "\" : "\\pumvisible() ? "\" : "\\pumvisible

I think it might be conflicting with coc nvim?

relevant coc nvim config

inoremap <expr> <cr> pumvisible() ? "\<C-y>" : "\<C-g>u\<CR>"

[actioninja]

Occurs with deoplete as well
After some further testing, this actually appears to be some kind of bad config interaction with pumvisible() which isn't specific to any one completion plugin.
Commenting out this block in my config fixes the issue:

inoremap <expr> <CR>       pumvisible() ? "\<C-y>" : "\<CR>" 
inoremap <expr> <Tab>      pumvisible() ? "\<C-n>" : "\<Tab>"
inoremap <expr> <S-Tab>    pumvisible() ? "\<C-p>" : "\<S-Tab>"

[wbthomason]

I use the following snippet to resolve this issue across plugins:

inoremap <silent><expr> <cr> <sid>handle_cr()

function! s:handle_cr() abort
  return pumvisible() ? "\<C-y>" : "\<C-g>u\<CR>"
endfunction

[dialtone]

Still broken for me. Effectively on open paren and <CR> it ends up pasting over and over the same few characters from coc.vim for some reason.