• nvim --version:

λ nvim --version
NVIM v0.5.0-dev
Build type: Release
LuaJIT 2.1.0-beta3
Compilation: 
Compiled by nixbld

Features: +acl +iconv +tui
See ":help feature-compile"

   system vimrc file: "$VIM/sysinit.vim"
  fall-back for $VIM: "
/nix/store/0ksh7zkgn9463c3wgpcz0axy192hz1ga-neovim-unwrapped-0.4.3/share/nvim
"

Run :checkhealth for more info

• nvim-lsp version(commit hash): don't know, installed today with vim-plug
• :checkhealth result: everything seems ok except for missing python/ruby/node/perl
• What language server: rust-analyzer
• Operating system/version: NixOS 20.03
• Terminal name/version: kitty 0.16.0
• $TERM: xterm-kitty

How to reproduce the problem from neovim startup

• install nvim-lsp in basic configuration

λ cat ~/.config/nvim/init.vim 
call plug#begin('~/.local/share/plugged')
Plug 'neovim/nvim-lsp'
call plug#end()
lua <<EOF
require'nvim_lsp'.rust_analyzer.setup{}
EOF

• install rust-analyzer

• open hello-world rust project and start typing

Actual behaviour

Transient syntax errors shift the whole character grid and in general feel very disruptive

https://asciinema.org/a/gwwim5tVtoORsg5cekqdCYXn8

Expected behaviour

Language servers provide immediate feedback about syntax errors, so it is important that this feedback is not distracting from writing the code. The perfect solution would be a red squiggly. My undestanding is that this is impossible to do in a terminal, but:

• something like underlining or just using a different color should be possible
• the character grid is shifted even when using gui (gnvim, nvim-qt)

It might be useful to see what emacs does in default (modulo color theme) configuration:

https://asciinema.org/a/Hgcp8Zlzk1wtgFeUYCqOxCAoN

It just colors the erroneous code in red. With this color scheme it is probably too subtle, but at least the editing itself is not interrupted.

Also, I must say otherwise the out-of-the-box experience of nvim-lsp feels better: the server is started automatically, and the delay between edits and error pop-ups is much smaller!