Re: [BUG] "git diff --word-diff" gives a diff while they are only space changes

[Vincent Lefevre <vincent@vinc17.net>]

On 2026-05-14 16:37:39 +0900, Junio C Hamano wrote:
> Michael Montalbo <mmontalbo@gmail.com> writes:
> 
> > @@ -457,6 +457,11 @@ endif::git-diff[]
> >  +
> >  Note that despite the name of the first mode, color is used to
> >  highlight the changed parts in all modes if enabled.
> > ++
> > +Word diff works by finding word-level changes within each hunk of
> > +the line-level diff.  The line-level alignment determines which
> > +changed lines are compared to each other, which can affect the
> > +word-level output.
> 
> The added text may not say anything wrong, but I am not sure how it
> helps the end user to know the way machinery works internally.

Perhaps only the first sentence should be kept and that the following
should be added: "Because of that, using the --ignore-space-change
option is recommended."

Note: Earlier in the discussion, Johannes Sixt suggested -w
(--ignore-all-space), but this is wrong, as

  git diff --word-diff -w <(printf foo) <(printf "f o o")

gives no differences while one has 1 word "foo" vs 3 words "f o o".

However, --ignore-space-change is actually not even sufficient
since

  git diff --ignore-space-change <(printf "foo bar") <(printf "foo\nbar")

finds differences though there are only space changes (thus this
may affect hunks in case --word-diff would be used too). However,
I suppose that the cases where --word-diff --ignore-space-change
would not give a "real word diff" would be quite rare in practice.

-- 
Vincent Lefèvre <vincent@vinc17.net> - Web: <https://www.vinc17.net/>
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