Is there a way to configure vimdiff to ignore ALL whitespaces?

Solution 1:

This implements what you want (taken from the diffexpr docs with -b changed to -w):

set diffopt+=iwhite
set diffexpr=DiffW()
function DiffW()
  let opt = ""
   if &diffopt =~ "icase"
     let opt = opt . "-i "
   endif
   if &diffopt =~ "iwhite"
     let opt = opt . "-w " " swapped vim's -b with -w
   endif
   silent execute "!diff -a --binary " . opt .
     \ v:fname_in . " " . v:fname_new .  " > " . v:fname_out
endfunction

... I'm still looking for a better diffexpr helper with respect to handling which lines map to which (GNU diff, even with -w instead of -b, is rather baffled by combining extra whitespace with minor edits like commented lines). Maybe diffchar?

Solution 2:

Yes. Set the iwhite option as you did, but additionally, make diffexpr empty.

From the relevant section of the vim docs:

iwhite

Ignore changes in amount of white space. Adds the "-b" flag to the "diff" command if 'diffexpr' is empty. Check the documentation of the "diff" command for what this does exactly. It should ignore adding trailing white space, but not leading white space.

Note also that you can provide a custom diff command line by setting diffexpr. See the discussion on the vimdiff man page, in particular:

The 'diffexpr' option can be set to use something else than the standard "diff" program to compare two files and find the differences.

When 'diffexpr' is empty, Vim uses this command to find the differences between file1 and file2:

diff file1 file2 > outfile

Solution 3:

Thanks ire, that helped me. I now only need to have this (simpler than what is proposed by Adam K) in my ~/.vimrc :

set diffopt+=iwhite

set diffexpr=""

And it does it... That is still the most powerfull diff tool I know of, far better than any other.