Syntax highlighting gone when using buffer

Question

At work I usually keep only a few files in buffer, typically a Yang file, a Java file, and possibly something like a readme file. In such an environment, the Yang syntax highlighting does not work. Example "run":

$ vim yangfile.yang # Yang syntax highlighting works
:e Foo.java         # new or existing file, doesnt'matter
:bnext              # Yang syntax highlighting is gone, all text is white
:so ~/.vimrc        # this does not work

My .vimrc is quite small, it starts with source ~/yang.vim (this file is available here) and then less than 50 more lines of pretty basic Vim configurations (I can edit my question to include the entire .vimrc on request).

How can I fix this problem? Thanks.

Answer 1

Thanks to David Ben Knoble's comment I was able to find relevant information and solve my problem. I did as follows and it worked for me:

In .vimrc, remove source ~/yang.vim, add :syntax on and :filetype plugin on (I added them to the top of the file). Inside vim (normal mode), type :set runtimepath?. In my case one of the directories printed was ~/.vim. Move yang.vim to ~/.vim/syntax (create if needed). Finally, create ~/.vim/ftdetect/yang.vim (create subdir if needed) and enter the following in that file:

au BufRead,BufNewFile *.yang set filetype=yang

Done and done. Useful links:

Vim 101: runtimepath

Creating your own syntax files