Mixing two syntax highlighting scripts
vim
Solution
Quick fix: append `syntax on` to the last line of your `.vimrc`, which is the same as setting `:syn on` in the live session.
Not So Quick:
Looks like you might have installed the custom 'jekyll' syntax alongside the default syntax files in `$VIMRUNTIME`.
According to Vim wiki section on custom syntax, it's preferable to keep all personal customizations within `~/.vim`. For example, putting your `jekyll.vim` syntax in `~/.vim/syntax/`.
Do not use a directory containing the files distributed with Vim because that will be overwritten during an upgrade (in particular, do not use the $VIMRUNTIME directory).
In the Vim syntax docs: `:syntax enable` runs ':source $VIMRUNTIME/syntax/DEFAULT_SYNTAX.vim'. `:syn on` (or `:syntax on`) will "overrule your settings with the defaults".
So if setting `:syntax on` makes your custom syntax work, it must be contained in the default syntax set.
Try keeping all the custom stuff in `~/.vim` and see if that settles things.
Problem
I write blog posts with Jekyll, and for that I end up using three different languages in the same file: YAML at the start for post metadata, Markdown in the body, and C++ in code snippets. I tried to setup a script so that I can have vim highlight all three properly for me, and ended up with something like this in syntax/jekyll.vim: ``` " Build upon Markdown syntax runtime! syntax/markdown.vim " pretend there's no syntax loaded unlet b:current_syntax " Bring in YAML syntax for front matter syntax include @Yaml syntax/yaml.vim syntax region yamlFrontmatter start=/\%^---$/ end=/^---$/ keepend contains=@Yaml " pretend there's no syntax loaded unlet b:current_syntax " Bring in C++11 syntax for code snippets syntax include @Cpp syntax/cpp.vim syntax region cppCodeSnippet matchgroup=Comment start=/^{% highlight cpp %}$/ end=/^{% endhighlight %}$/ keepend contains=@Cpp let b:current_syntax='jekyll' ``` I also set up a file detection script to set `ft` to this syntax. It almost works. When I open a file that gets detected as this type, I get everything correct except for the C++ highlights. However, if I type `:syn on` after that, everything works fine. I can delete the buffer and open the file again and all highlights are ok. If I close vim and start it again, I need to run `:syn on` again. What am I missing? How can I debug this issue?