[Update from 2020-03-27 below]
Vim's diff mode is a lightweight diffing tool that can be used at the command line, in particular with the
git diff command. In a previous post, I wrote about configuring vimdiff as the git difftool for use with Matlab development (yes, way back when I was actually writing Matlab code).
Recently, I've been getting errors using vimdiff of the following (showing manual invocation rather than through
$ vimdiff Error detected while processing /Users/micahsmith/.vimrc: line 65: E474: Invalid argument: diffopt+=iwhite Press ENTER or type command to continue
The corresponding section of my .vimrc file is as follows:
"Ignore whitespace with vimdiff if &diff set diffopt+=iwhite endif
Had a new version of vim been released that deprecated this
diffopt option? No,
iwhite still appeared in the manual under
:help diffopt. This error was driving me crazy, as when I ran
git diff when there were many changed files, this error message would display for me to acknowledge between every file comparison.
After beating my head against the wall for a while, I finally figured out the issue. Most of my frustration is environment specific, but it does seem like MacOS Catalina bundled a different version of vim that removed support for the
iwhite option. I'm not going to dive into it too thoroughly, but if you confirm that Catalina is to blame, let me know in the comments.
I don't use the system version of vim anyway, instead using MacVim installed using Homebrew Cask. So why was this causing me problems? I realized that I had been using an alias to invoke MacVim from the terminal but that my alias did not capture invocation of the form
vimdiff which used the system
vim. Uninstall MacVim and reinstalling it caused it to re-install symlinks including
/usr/local/bin/vim, a command that did not exist as such when I originally installed MacVim.
git difftoolset to
vimdiffwhich pointed to system
/usr/bin/vimand was unaffected by
- upgrade to MacOS Catalina involved upgrade of system
vimwhich dropped support for
- re-install MacVim (
brew cask zap macvim && brew cask install macvim) which created a symlink at
/usr/local/binalready higher on my
git difftoolset to
vim -d(equivalent to vimdiff but hopefully less likely to cause future path issues)
I dove deeper into the source of the problem on the version of vim provided by MacOS
Catalina and I was able to identify the problem more clearly and find a solution. First, the
Catalina vim version did not drop support for iwhite. Rather, the problem is that somehow
the default setting which includes
internal is invalid for the version of vim installed.
Here is a log demonstrating the issue.
$ /usr/bin/vim -u NONE :set diffopt? diffopt=internal,filler :set diffopt+=iwhite E474: Invalid argument: diffopt+=iwhite :set diffopt=internal E474: Invalid argument: diffopt=internal :set diffopt=filler :set diffopt+=iwhite :set diffopt? diffopt=filler,iwhite
- stock vim with no config defaults to
- stock vim does not actually support the option
:help diffoptis actually accurate in this regard in that it is not shown as an option, though it is listed as the default)
:set diffopt+=iwhitesemantically does
:set diffopt=internal,filler,iwhitewhich contains an invalid option
- the error message is highly misleading suggesting that the invalid argument is
iwhitewhen it is actually
A quick fix
- first remove
internalfrom the list of options
- then add your desired options
if &diff set diffopt-=internal set diffopt+=iwhite endif
My version of vim FWIW:
$ /usr/bin/vim --version VIM - Vi IMproved 8.1 (2018 May 18, compiled Dec 13 2019 14:45:40) Included patches: 1-503, 505-680, 682-1312 Compiled by firstname.lastname@example.org