One of my files has an incorrect tabstop setting

Question

One of my files, whenever I open it, has a different (incorrect) value for the 'tabstop' option. In my .vimrc, I have the line:

set tabstop=4 softtabstop=4 shiftwidth=4 noexpandtab

and 'tab' is not mentioned in any subsequent lines. When I open a specific file I'm working on, the 'tabstop' option is set to 8, while all the other relevant options are correct; and all other files (so far) show their indentation correctly. I don't use modelines or smart tabs (yet). If I source my vimrc in the file, it corrects the indentation, so I'm assuming it isn't anything directly related to vimrc. What is happening?

Answer 1

Basically there's two ways in which your .vimrc can be superseeded: plugins (including filetype-specific ones) might reset the option, or it might be changed by an autocommand. In any case, your first step is to check when the option was last modified (see :set-verbose):

:verbose set tabstop?

If that's not enough, look through the list of all the scripts and config files that Vim has read since it was started:

:scriptnames

(better do that in a newly started copy of Vim right after loading the offending file—this way, there'll be less output from :scriptnames.)

After these steps, you should have a list of scripts that might be the culprits. There's no easy way to narrow it down: you'll have to grep, to temporarily remove plugins from your ~/.vim and so on.

Finally you'll find a line that changes the setting. If it's in a plugin, look through its documentation to find a way to override the setting. If it's somewhere in the indent file or ftplugin, override its effect by placing a file into ~/.vim/after/indent/ or ~/.vim/after/ftplugin. An autocommand might also work.