git merge ignoring whitespace

git merge ignoring whitespace

[layer]

Junio, on 3/25/07 you said:

  I know Linus does not like applying patches with whitespace
  fuzziness, but I personally think a merge that ignores
  whitespace changes would be a useful thing to have, without
  having to call an external specialized merge backend. In other
  words, I do not think it is so special a thing to want to, but
  it is rather an unfortunate norm.  I am not opposed to give
  git-merge-recursive a command line option to tell it to merge
  ignoring the whitespace-only changes, when it does the 3-way
  file-level merge internally.

Whatever came of this?  I tried giving git merge a --ignore-whitespace
argument and the error message that followed show no equivalent
argument.

It would sure come in handy right now.  Is there some other way to do
it that I didn't find searching the mailing list?

Thanks.

Kevin

Re: git merge ignoring whitespace

[Junio C Hamano]

layer <layer@known.net> writes:

> Junio, on 3/25/07 you said:
>
>   I know Linus does not like applying patches with whitespace
>   fuzziness, but I personally think a merge that ignores
>   whitespace changes would be a useful thing to have, without
>   having to call an external specialized merge backend. In other
>   words, I do not think it is so special a thing to want to, but
>   it is rather an unfortunate norm.  I am not opposed to give
>   git-merge-recursive a command line option to tell it to merge
>   ignoring the whitespace-only changes, when it does the 3-way
>   file-level merge internally.
>
> Whatever came of this?

I do not know.  When I say "I am not opposed to", I mean just that. 

I may consider it a bad mode of operation, and I may hesitate to encourage
people to use it as their default.  But I do not feel strongly enough to
veto it---as long as it is a rope you need to explicitly ask for to hang
yourself with, I think it is Ok if we allowed such an option.

It is not my itch to scratch, and I do not keep track.

Did you submit a patch that implements the new feature cleanly?

Re: git merge ignoring whitespace

[layer]

Junio C Hamano <gitster@pobox.com> wrote:

>> layer <layer@known.net> writes:
>> 
>> > Junio, on 3/25/07 you said:
>> >
>> >   I know Linus does not like applying patches with whitespace
>> >   fuzziness, but I personally think a merge that ignores
>> >   whitespace changes would be a useful thing to have, without
>> >   having to call an external specialized merge backend. In other
>> >   words, I do not think it is so special a thing to want to, but
>> >   it is rather an unfortunate norm.  I am not opposed to give
>> >   git-merge-recursive a command line option to tell it to merge
>> >   ignoring the whitespace-only changes, when it does the 3-way
>> >   file-level merge internally.
>> >
>> > Whatever came of this?
>> 
>> I do not know.  When I say "I am not opposed to", I mean just that. 
>> 
>> I may consider it a bad mode of operation, and I may hesitate to encourage
>> people to use it as their default.  But I do not feel strongly enough to
>> veto it---as long as it is a rope you need to explicitly ask for to hang
>> yourself with, I think it is Ok if we allowed such an option.
>> 
>> It is not my itch to scratch, and I do not keep track.

Thanks for the summary.

>> Did you submit a patch that implements the new feature cleanly?

Nope.  I'm just barely emerging from newbie status, so I'm probably a
ways away from implementing it.

Kevin

Re: git merge ignoring whitespace

[Johannes Schindelin]

Hi,

On Thu, 5 Feb 2009, layer wrote:

> Junio, on 3/25/07 you said:
> 
>   I know Linus does not like applying patches with whitespace
>   fuzziness, but I personally think a merge that ignores
>   whitespace changes would be a useful thing to have, without
>   having to call an external specialized merge backend. In other
>   words, I do not think it is so special a thing to want to, but
>   it is rather an unfortunate norm.  I am not opposed to give
>   git-merge-recursive a command line option to tell it to merge
>   ignoring the whitespace-only changes, when it does the 3-way
>   file-level merge internally.
> 
> Whatever came of this?  I tried giving git merge a --ignore-whitespace
> argument and the error message that followed show no equivalent
> argument.

I can think of two issues:

- there was this -X patch by Junio, but I think it is a bad interface to 
  pass merge backend options, as it is not closely coupled with the 
  backend.  Just imagine this:

	git merge -X ignore-whitespace -s resolve,recursive

  Does the "-X ignore-whitespace" impact resolve, recursive, or both?  And 
  we'd need some way to specify the option to the backend.  I thought that

	git merge -s resolve,recursive/ignore-whitespace

  would be a sane syntax, but at least _I_ did not have a need to pass 
  backend options yet.

- more fundamental, how should the merge ignoring whitespace work?  Which 
  version would it take if the lines agree _except_ for whitespace 
  changes?  This needs to be well designed, as we have not only merges 
  (where we have "ours" and "theirs"), but also rebases (where we have 
  "theirs" and _then_ "ours"), and of course recursive merges when there 
  is more than a single merge base (and there, it gets really nasty, so 
  you better have the semantics of the whitespace-ignoring merge put down 
  quite clearly).

> It would sure come in handy right now.  Is there some other way to do
> it that I didn't find searching the mailing list?

Of course, you could try to "normalize" the whitespace, and perform the 
merge after that.

Ciao,
Dscho