[Svnmerge] Log of merges

[Blair Zajac]

Giovanni Bajo wrote:
> Archie Cobbs <archie at dellroad.org> wrote:
> 
> 
> 
>>>a GCC branch maintainer has asked me for a way to tell svnmerge
>>>"jump me back 3 merges ago". While I believe that calling "svn up"
>>>is a bit too much for svnmerge, this request gave me an idea for a
>>>new feature: we could implement a "svnmerge log" command which
>>>shows the list of all merges happened in the branch. This would
>>>allow to easily implement the jump-back command as a wrapping
>>>script (or give the basis to code it within svnmerge, if we want it
>>>there).
> 
> 
>>First of all, what does "jump me back 3 merges ago" mean? There
>>are a couple of interpretations.
>>
>>If the desire is to revert the past N merges (but not any intervening
>>non-svnmerge commits), my first thought would be to use the normal svn
>>mechanism for this: review the log, then "svn merge" the reversed
>>changes. Note that this will revert the svnmerge-integrated property
>>as well.
>>
>>If the desire is simply to update to a prior revision, "svn up -r ..."
>>works just fine...
> 
> 
> 
> I'll have to further investigate the needs of the maintainer. What I have
> understood is that, using svnmerge, he looses what he considers a valuable
> information, that is the multiple merge tags. With CVS, they were always around
> for obvious reasons, and he often uses the last 3/4 merge tags for diff
> operations and whatnot. I believe the typical questions are: "what was changed
> in this file since last merge?", "if I rollback to immediately after last
> merge, does this bug show up? What if I go back two merges? Or three?".

Some of this sounds like svn training.  I found that some people coming from CVS 
have to shift the way they think to work inside of svn's model of the repository.

Well, using the PREV is the easiest way to do that, at least to move back in 
time.  Another useful command to answer some of these is to do 'svn diff -r 
PREV:BASE', which will show you what's changed from the last commit to the 
revision in the working copy.

> With CVS, you could answer this with things liks "cvs
> diff -rMYBRANCH_MERGE_20051022 foo.c", and "cvs up -rMYBRANCH_MERGE_20051014
> foo.c". You can almost do the same if you use multiple merge tags with SVN (the
> required command line is much longer, and this is being discussed right now in
> the dev subversion mailing list). With svnmerge, one has to manually inspect
> the full log of the branch to find the wanted revision numbers, and use those
> numbers. This is much more burdesome, especially if compared to a "svn ls" to
> get the merge tag names.

Agreed, that is harder with svn.

Do you have the subjet line for the thread discussing this issue on the mailing 
list or link to the thread.

> This is why I was proposing "svnmerge log": we do the tedious work of finding
> out the merges, and show those.

I do think having a command that would tell you the commits that svnmerge 
generated would be useful.  This does get into the problem of how to get that 
easily into svn, with the fact that the revision svnmerge gets isn't known until 
the commit happens.

Maybe there should be a hidden .svnmerge-data file which has svn:keywords set to 
Revision and every commit through svnmerge changes the file slightly.  Also, 
when svnmerge runs, it pulls the revision out of that file and dumps it into a 
svnmerge property on the directory.  So when you ask for merged revisions, you 
check the property and the one file.

Regards,
Blair