Re: Finishing the repository conversion

[Joseph Myers <joseph at codesourcery dot com>]

On Sat, 9 Dec 2017, Eric S. Raymond wrote:

> One thing my software can do now that it couldn't do six months ago
> is mine Author fields from ChangeLog histories.  So you'll get a
> better-quality conversion than if I had been able to finish this then.

Observations from the code for doing this, without having run experiments:

* As I understand it, it sets an author date for a commit based on the 
ChangeLog date, as well as setting the commit author (separate from the 
committer which I presume remains as converted by the author map).  I'd be 
very wary of that giving good information; in general I think copying the 
committer date to the author date is probably better.  People writing 
ChangeLog entries manually often get the date very wrong - maybe a 
completely wrong year (20017-12-11), maybe the previous year (2017-01-01 
when it's actually 2018-01-01), maybe the wrong month, maybe swap month 
and date.  The previous discussions on the gcc list had some people 
wanting better author attributions based on ChangeLog entries; I don't 
think anyone was expecting anything useful to come from dates in 
ChangeLogs.

* There's an older ChangeLog style that the code doesn't handle but which 
can be found in older GCC commits, with header lines such as:

Tue Dec  9 01:16:06 1997  Jeffrey A Law  (law@cygnus.com)

This format sometimes has the email address surrounded by (), sometimes by 
<>.  There are a few log entries with a hybrid of old and new forms, where 
there is a yyyy-mm-dd date but an email address surrounded by ().

-- 
Joseph S. Myers
joseph@codesourcery.com