Re: co-authoring commits

From: Jeff King <peff@peff.net>
Date: Jun 19, 2015, 04:25 UTC
Message-ID: <20150619042519.GB26001@peff.net>
In-Reply-To: <55833758.6010000@gmail.com>

On Thu, Jun 18, 2015 at 11:25:44PM +0200, Jakub Narębski wrote:

Show 6 quoted lines

> Author and committer include datetime in the contents of the
> field, which is used by Git for heuristics limiting walk. Coauthor
> would have the same date as author, isn't it? If, after long
> and involved discussion, we didn't add 'generation' field (for
> easier cutting history walking), what chance adding 'coauthor'
> has.

I don't think the two situations are comparable. I would (and did) argue that a "generation" field is a bad header to bake in because of what it means (it is redundant with the graph structure).

Whereas "co-author" is not a fundamentally bad; it's just not something we chose to support early on, and it would have to be added now.

> OTOH it would be nice to have support for .mailmap, and for
> grepping... but the former could conceivably be added to the trailer
> tool, the latter can be done with appropriate regexp in
> "git log --grep=...".

I don't think we munge trailers during "git log" pretty-printing at all now, but it is certainly something we could add (including mailmap-ing them). That doesn't seem like much more work than showing the co-author field, and it's a lot more generally applicable (you could mailmap S-O-B, Reviewed-by, and so forth).

Similarly, something like "git shortlog" would have to learn about multiple authors under the "co-author" scheme. But likewise, it would not be much more work to teach it something like:

  git shortlog --field=Reviewed-by

to handle an arbitrary trailer. And that is much more flexible.

> I wonder what would break if one used 'Name <e@mai.l>, Name <em@i.l>'
> as the author...

The "normal" parser we use for pretty-printing goes left-to-right and will stop at the first ">", and show only the first author.

Older versions of git would then get the date wrong, complaining about the ",". Newer versions parse the date from right-to-left to work around such bogosities (especially things like "<foo <bar>>") and so will parse back to the second ">".

Fsck will definitely complain about it.

-Peff