From mboxrd@z Thu Jan  1 00:00:00 1970
From: Junio C Hamano <gitster@pobox.com>
Subject: Re: weird diff output?
Date: Tue, 29 Mar 2016 10:54:34 -0700
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Cc: Jacob Keller <jacob.keller@gmail.com>,
	Git mailing list <git@vger.kernel.org>,
	Jens Lehmann <Jens.Lehmann@web.de>
To: Stefan Beller <sbeller@google.com>
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In-Reply-To: <CAGZ79ka4ad5dQMWANJUDx-0+kV3qR=HttOJni2XfhFzjMKfcPw@mail.gmail.com>
	(Stefan Beller's message of "Tue, 29 Mar 2016 10:37:38 -0700")
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Stefan Beller <sbeller@google.com> writes:

> I thought this is an optimization for C code where you have a diff like:
>
>     int existingStuff1(..) {
>     ...
>     }
>     +
>     + int foo(..) {
>     +...
>     +}
>
>     int existingStuff2(...) {
>     ...
>
> Note that the closing '}' could be taken from the method existingStuff1 instead
> of correctly closing foo.

That is a less optimal output.  Another possible output would be
like so:

      int existingStuff1(..) {
      ...
      }
     
     + int foo(..) {
     +...
     +}
     +
      int existingStuff2(...) {

All three are valid output, and ...

> So the correct heuristic really depends on what kind of text we
> are diffing.

... this realization is correct.

I have a feeling that any heuristic would be correct half of the
time, including the ehuristic implemented in the current code.  The
readers of patches have inherent bias.  They do not notice when the
hunk is formed to match their expectation, but they will notice and
remember when they see something less optimal.