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

> 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.