Shougo

I think cmdline UI should be implemented by `ext_cmdline`. current solution is very adhoc.

Related: https://github.com/neovim/neovim/pull/16396

Please test https://github.com/neovim/neovim/pull/20188.

Related: https://github.com/kyazdani42/nvim-tree.lua/issues/1502

`cmp_nvim_lsp` seems not installed. You should check it is installed properly.

What is the pre-defined register? clipboard register is only shared. The other registers are not shared.

It is the problem of nvim-cmp? I think it is clangd's feature. I think to gather candidates is very slow. And it does not provide all candidates quickly.

OK. The result seems cached.

https://github.com/hrsh7th/nvim-cmp/issues/938

`nvim-cmp` uses original popup menu framework. So `nvim-cmp` cannot use it. `nvim-cmp` already implement `ddc-cmdline` feature. `ddc-input` feature is needed.