In what order does Vim read ftplugin files, syntax files, and the .vimrc when the commands (e.g. set syntax=mysyntax, filetype plugin on) are called?

Question

I've had some issues lately reconciling my .vimrc with files in ftplugin and after/ftplugin. In what order are all these things read?

For example: when I call in my .vimrc the command plugin filetype on, is the filetype program read immediately, or after the rest of .vimrc is read? Furthermore, I'm guessing the order is that first Vim checks for a .vim/ftplugin/myfiletype.vim file before loading the "default" myfiletype.vim in $VIMRUNTIME, if it found nothing then runs the default file, and then checks for fies in .vim/after/ftplugin?

Also when set syntax=myfiletypesyntax is called, are those lines read immediately or at the end of file?

Answer 1

When filetype plugin on is encountered in your vimrc, $VIMRUNTIME/ftplugin.vim is immediately executed. This creates an auto command which does the following:

exe 'runtime! ftplugin/' . name . '.vim ftplugin/' . name . '_*.vim ftplugin/' . name . '/*.vim'

This executes all matching files in each directory in 'runtimepath'.

Note that auto commands are executed in the order in which they are defined, so if you have the following in your vimrc:

au filetype php echoerr 'before'
filetype plugin on
au filetype php echoerr 'after'

And have this at the top of $VIMRUNTIME/ftplugin/php.vim:

echoerr 'during'

Then you will see the errors 'before', 'during', 'after' echoed in sequence when you edit a php file.