Question

Note

I am using the local vim plugin that allows me to use a project-specific .vimrc file, in general it works fine and as you’d expect.

Background

I work with Silverstripe, and therefore have to work with Silverstripe templates, which are *.ss files, however by default vim assigns *.ss to scheme files. Now I only use Silverstripe for one project, and have been using the html filetype set in my project-specific .vimrc for highlighting, however after encountering a few bugs, I figured that I would add the highlighting for *.ss files in an htmlss.vim file (using html.vim as a base, i just added the template rules near the end). After a bit of trial and error I got it working and highlighting properly, however i have encountered a strange bug…

Question

Using this project .vimrc:

augroup filetypedetect
    autocmd! * *.ss
    autocmd! BufEnter *.ss setf htmlss
augroup END

Everything works fine, however, using this .vimrc:

augroup filetypedetect
    autocmd! * *.ss
    autocmd! BufEnter,BufRead,BufNewFile *.ss setf htmlss
augroup END

The syntax highlighting fails, it sets the filetype correctly, but the highlighting goes screwy.

I guess I want to know why version 1 works, but version 2 doesn’t, despite nothing else changing.

Addendum

After a little more investigation, i have found that removing autocmd! * *.ss makes the second one work, only if i remove ! from the autocmd! BufEnter,BufRead,BufNewFile *.ss setf htmlss. i.e.

augroup filetypedetect
    autocmd BufEnter,BufRead,BufNewFile *.ss setf htmlss
augroup END

works but

augroup filetypedetect
    autocmd! BufEnter,BufRead,BufNewFile *.ss setf htmlss
augroup END

and

augroup filetypedetect
    autocmd! * *.ss
    autocmd BufEnter,BufRead,BufNewFile *.ss setf htmlss
augroup END

do not.

Again, my question is why these difference occur, i have a working implementation now, so i am not interested in any investigation. I don’t want solutions as i have no problem.

Answer 1

This is probably caused by your syntax file conflicting with itself when applied multiple times. One of the first lines in the syntax file is probably syntax enable, which enables syntax without changing any of the current highlight settings. Per the docs:

The ":syntax enable" command will keep your current color settings.  This
allows using ":highlight" commands to set your preferred colors before or
after using this command.  If you want Vim to overrule your settings with the
defaults, use:
        :syntax on

So, an adequate “solution” should be to change syntax enable to syntax on in the syntax file.