Vim: `set formatoptions` being lost? - vim

Question

I've got set formatoptions=cqn in my vimrc, but for some reason it doesn't stick. It seems like Vim is reverting to the default (fo=tcq) at some point… But I can't figure out why. Running -V100/tmp/log just gives me:
formatoptions=tcq
Last set from ~/.vimrc
With no useful context.
So, is there any way to make formatoptions stick? Or do I just need to create an autocmd to reset it each time a new file is loaded?
Edit
Using :verbose set formatoptions shows this:
formatoptions=tcq
Last set from ~/.vimrc
However, the only reference to fo or formatoptions in my ~/.vimrc is set formatoptions+=cqn.

Answer 1

This behavior is because of C file plugin in VIM. Since file plugin is loaded after loading .vimrc, the settings in .vimrc are overwritten.
The solution given by David Wolever seems to be the best option.
Add the following line in .vimrc:
autocmd BufNewFile,BufRead * setlocal formatoptions+=cqn
...instead of the normal set formatoptions command.

Answer 2

I ran across this problem too. I had project-specific configurations something like
autocmd BufRead,BufNewFile project/*.c setlocal formatoptions-=cro
However, set fo? showed formatoptions=croql. Turns out, I needed BufWinEnter instead of BufRead:
After a buffer is displayed in a window. This
can be when the buffer is loaded (after
processing the modelines) or when a hidden
buffer is displayed in a window (and is no
longer hidden).
Does not happen for :split without
arguments, since you keep editing the same
buffer, or ":split" with a file that's already
open in a window, because it re-uses an
existing buffer. But it does happen for a
":split" with the name of the current buffer,
since it reloads that buffer.
So this works
autocmd BufWinEnter,BufNewFile project/*.c setlocal formatoptions-=cro

Answer 3

According to the vim documentation on formatoptions:
NOTE: This option is set to the Vi
default value when 'compatible' is
set and to the Vim default value when
'compatible' is reset.
So if the value of compatible is changing along the way, that could be causing the issue you're seeing.

Answer 4

I does sound like some file either sourced from your .vimrc or plugins are changing that value.
Something to try to pinpoint it is
start vim without sourcing anything, use
vim -u NONE
Using NORC skipps .vimrc but loads plugins
Check :help --noplugin to read about various startup-options that controls the sourcing.
--noplugin Skip loading plugins. Resets the 'loadplugins' option.
{not in Vi}
Note that the |-u| argument may also disable loading plugins:
argument load vimrc files load plugins ~
(nothing) yes yes
-u NONE no no
-u NORC no yes
--noplugin yes no
Perhaps this might be useful as well (from help: :set):
When 'verbose' is non-zero, displaying an option value will also tell where it
was last set. Example: >
:verbose set shiftwidth cindent?
< shiftwidth=4 ~
Last set from modeline ~
cindent ~
Last set from /usr/local/share/vim/vim60/ftplugin/c.vim ~
perhaps... :-)
Edit
Are you using compatible? From help: formatoptions
NOTE: This option is set to the Vi default value when 'compatible' is
set and to the Vim default value when 'compatible' is reset.

Answer 5

Found in /usr/share/vim/vim74/ftplugin/vim.vim:
" Set 'formatoptions' to break comment lines but not other lines,<br>
" and insert the comment leader when hitting <CR> or using "o".<br>
setlocal fo-=t fo+=croql
Remove it. Then all things done.