Vim 8.1 Globally custom highlight colors

Question

Problem

I'm finally getting around to upgrading from Vim 7.4 to Vim 8.1, but my global custom highlight colors have stopped working.

I am aware similar questions (such as this one) have been asked, but these all seem to be related to the closed Issue #542, and none of the solutions there seem to work for me.

Version Info

8.1 from the jonathonf/vim ppa repository on Ubuntu 18.04.

VIM - Vi IMproved 8.1 (2018 May 18, compiled Aug 22 2018 11:42:48)
Included patches: 1-346
Modified by jonathonf.fernyhough@york.ac.uk

Full --version text (Pastebin link) I also tried Vim 8.0 from Ubuntu 18.04's vim package

Minimum steps to reproduce

Create the following .vimrc file:

echo "Read the correct vimrc"
hi Comment ctermfg=green cterm=none

Edit any file with comments; "Read the correct vimrc" is displayed, but the comment color is not green.

Additionally, sometimes I can see the color change a few milliseconds after the file is opened, suggesting something may indeed be overriding my settings.

Running :hi Comment ... from within vim works as expected.

Running vim with/without -u .vimrc does not make a difference.

Other things I've tried

I've tried using the autocmd suggestion from the above linked answer, to no avail. In short, that looks something like this:

augroup customhighlight
        autocmd!
        autocmd ColorScheme * hi Comment ctermfg=green
augroup end

---

I then went down the rabbit hole of vimrc defaults:

   system vimrc file: "$VIM/vimrc"
     user vimrc file: "$HOME/.vimrc"
 2nd user vimrc file: "~/.vim/vimrc"
      user exrc file: "$HOME/.exrc"
       defaults file: "$VIMRUNTIME/defaults.vim"
  fall-back for $VIM: "/usr/share/vim"

Unfortunately, unless I missed something, there doesn't appear to be anything in the default/Debian vim defaults that would override a user .vimrc, and, indeed, that would be silly.

---

I have not gone down the route of implementing custom color schemes, which was another suggestion. Reason being, I work with a lot of different filetypes on a regular basis, and there has always been a way to globally customize colors, so I'm hoping there's a solution.

---

:verbose hi Comment reports:

Comment        xxx term=bold ctermfg=14 guifg=#80a0ff
        Last set from /usr/share/vim/vim81/syntax/syncolor.vim

:colorscheme reports default

Summary

What is the best practice to set global syntax highlight color preferences in Vim 8.x?

Answer 1

I don't know what changed between Vim 7.4 and 8.1 that caused this change in behavior, but the output of :verbose hi Comment that you posted provided a clue to a solution. :help syncolor suggests overriding the default highlighting colors by creating a file named ~/.vim/after/syntax/syncolor.vim (~\vimfiles\after\syntax\syncolor.vim on Windows) and putting in that file highlight commands like the following.

if &background == "light"
    highlight Comment ctermfg=darkgreen guifg=darkgreen
else
    highlight Comment ctermfg=green guifg=green
endif