Is there a conflict between `syntax enable` and custom keywords?

Question

I have the following minimal .vimrc file:

" syntax enable
syntax case match
syntax keyword MyTodo TODO PENDING 
syntax keyword MyTodoIP IN PROGRESS 
syntax keyword MyTodoClosed CLOSED COMPLETE DONE
hi MyTodo        ctermfg=yellow
hi MyTodoIP      ctermfg=darkgreen
hi MyTodoClosed  ctermfg=darkgray

As is, this works fine (TODO, etc are correctly highlighted). However, When I uncomment syntax enable, my syntax keywords are not highlighted as I have specified.

I looked at :help syn-enable and it says the following:

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.

I also tried using

syntax match MyTodoMatch "TODO"

with hi MyTodoWatch with the same result.

There is a similar question on stackoverflow from 2011 that seems to be having the same problem, but no solution so I'm posting here.

What am I missing here? How can I use syntax enable with custom keywords?

Additionally, with syntax enable 'enabled', I can source ~/.vimrc after opening vim and the desired syntax is applied correctly.

Answer 1

The only explanation I have, is that there is another syntax enable (or syntax on) somewhere.

Background: If syntax enable is executed and syntax was enabled before, all syntax items are cleared. See $VIMRUNTIME/syntax/syntax.vim line 12. The documentation only talks about :highlight, not :syntax.

If you have the directory $HOME/.vim with other setup files, rename it to $HOME/.vim.off and test again.

If that doesn't help, you could run:

vim -V15verbose.out ...

Replace ... with whatever you use to reproduce the problem. After Vim is started, check that the problem can be reproduced and exit Vim.

This command will write a trace of all commands to the file verbose.out. You can then grep that file for syntax enable or syntax on to check if there is another invocation.

Note that Vim appends to that file, so you might want to delete it between tries.

Update: You should also check verbose.log for sy clear, syn clear or syntax clear.