[RFC] health.vim: Fix tmux default-terminal check

[tweekmonster]

I ran :CheckHealth and was aghast when the tmux checker accused me of not setting default-terminal.

It was changed to a server option in 2.1. tmux's change log says it's a session option, but that's a typo.

[justinmk]

Oh, yuck. The problem is -qvgs doesn't work on older versions, at least not when I tried. I'm running tmux 1.8. So we probably have to check -qvg and then also -qvs. Hopefully not also -qvgs ...

[justinmk]

Oh, but we are using -qvgs for escape-time. Hmm..

[tweekmonster]

I was worried about that. Maybe we can just check tmux -V? But, that's also a little weird because now it will show master if you build from source.

[justinmk]

Just confirmed tmux show-option -qvgs default-terminal doesn't work but tmux show-option -qvgs escape-time does. And here's my .tmux.config:

set -g default-terminal "screen-256color"
set-option -g escape-time 2

So we can check both, and if at least one of them returns a sane value, assume it's good.

[justinmk]

something like this:

if tmux_default_term ==# ''
  let cmd = 'tmux show-option -qvgs default-terminal'
  let out = system(cmd)
  let tmux_default_term = substitute(out, '\v(\s|\r|\n)', '', 'g')
endif

Assuming -qvg variant returns empty on your system?

[tweekmonster]

I was just about to get on this 😀 Does it set a non-zero exit code? That'll be better than duplicating substitution.

[tweekmonster]

Found out in a docker container. Both just return empty strings.

[justinmk]

Good enough for now. We can DRY it later if more tmux checks are needed.