Re: Help understanding unexpected diff output

From: Junio C Hamano <gitster@pobox.com>
Date: Jul 13, 2020, 15:12 UTC
Message-ID: <xmqqsgdvo3ec.fsf@gitster.c.googlers.com>
In-Reply-To: <5F0C38BB020000A100039FF0@gwsmtp.uni-regensburg.de>

"Ulrich Windl" <Ulrich.Windl@rz.uni-regensburg.de> writes:

Show 6 quoted lines

> I inspected some changes using "git diff", and it was hard to me
> to find the actual differences (see git-diff-png): I had to look a
> long time at those olcAccess lines to find any difference, so
> finally I pasted both blocks into separate Emacs files a and b
> (via PuTTY) and used "ediff-files" (see diff-emacs.png).  Within
> there, the was only a part of one line changed!

With redactions and making them into two images, you did a good job killing interested parties' willingness to help, as they made using tools almost impossible.

So here is only based on eyeballing the images, and I probably have missed what you wanted readers to find, but don't blame me ;-)

It seems that the file got 6 lines removed, that begins with "olcAccess: {$n}" (0 <= n <= 6), at around 8th line of the file, and then very similar 6 lines that are not identical to what got removed at the end of the file. The ediff you showed tells me that the 6 lines removed from very early part of the file and 6 lines added to the end of the file are similar but not identical. These two 6-line blocks differ only by the 5th line (i.e. "olcAccess: {4}") having ",pwdGraceUseTime,pwdChangedTime" in the newer version, but not in the older version.

Am I reading what you sent us correctly so far?

Now, if this change to the "olcAccess: {4}" line in the new file weren't there, i.e. if the 6-line block that disappeared from the early part of the file and the 6-line block that was added near the end of the file were identical (in such a case, your ediff would show no changes, I presume), then what would your desired output from "git diff"?

I would imagine that the answer would still be a very similar looking

    --- a/0/...
    +++ b/0/...
    @@ -5,12 +5,6 @@
     olcDatabase: {1}hdb
     olcDbDirectory: /var/lib/ldap
     olcSuffix: dc=... 
    -olcAccess: {0} ...
    -olcAccess: {1} ...
    -olcAccess: {2} ...
    -olcAccess: {3} ...
    -olcAccess: {4} ...
    -olcAccess: {5} ...
    olcLimits: {0}dn.exact=....
     olcRootDn: cn=Admin,dc=...
     olcRootPW: {SSHA}yZ...
    @@ -52,6 +46,12 @@
     entryUUID: ...
     creatorsName: cn=config
     createTimestamp: ...
    -entryCSN: ...
    +olcAccess: {0} ...
    +olcAccess: {1} ...
    +olcAccess: {2} ...
    +olcAccess: {3} ...
    +olcAccess: {4} ...
    +olcAccess: {5} ...
    +entryCSN: ...
     modifiersName: cn=config
    -modifyTimestamp: ...
    +modifyTimestamp: ...

with identical "olcAccess: {$n}" lines removed from earlier part the file and added to the end of the file.

So I am not sure what you are asking. It would not be correct to show something like

    --- a/0/...
    +++ b/0/...
    @@ -52,6 +46,6 @@
     entryUUID: ...
     creatorsName: cn=config
     createTimestamp: ...
    -entryCSN: ...
    +entryCSN: ...
     modifiersName: cn=config
    -modifyTimestamp: ...
    +modifyTimestamp: ...

and pretend that the original "olcAccess: {$n}" lines did not get moved from the earlier part of the file to the end of the file.

Perhaps you may be looking for "git diff --color-moved"?  I dunno.