Re: "git diff" does not show a diff for newly added, binary files

From: Junio C Hamano <gitster@pobox.com>
Date: Apr 4, 2023, 15:42 UTC
Message-ID: <xmqqjzyr3b8e.fsf@gitster.g>
In-Reply-To: <8135fc7b-1953-4702-a9c4-b0f847e69887@app.fastmail.com>

"Kristoffer Haugsbakk" <code@khaugsbakk.name> writes:

Show 7 quoted lines

> On Tue, Apr 4, 2023, at 11:58, Thorsten Otto wrote:
>> "git diff" does not show a diff for newly added, binary files
>> […]
>> I expected a binary diff for the new file, just like it is done
>> when comparing two different, already committed revisions.
>
> Do you use `.gitattributes` to get these binary diffs? What does it look like?

The attribute "binary" can be used like this

    *.mybin	binary

to declare that all files with .mybin suffix are to be treated binary files. "git diff", "git format-patch", etc. will treat such a file as "binary".

What they actually do to "binary files" is a different story. The internal diff machinery by default shows "Binary files A and B differ" just like everybody else's "diff" program does, but has an option to show "binary patch" we invented. "git diff --binary" enables the option, and for some commands, the option is enabled by default.