Re: master cbef1e9 2/3: ; make change-history-commit

[Paul Eggert]

On 04/09/2015 11:24 AM, Glenn Morris wrote:
> I had assumed that the ChangeLog would not be versioned at all now,
> but it seems like it is?

No, your assumption is correct.  For example, there is no ChangeLog here:

http://git.savannah.gnu.org/cgit/emacs.git/tree/ChangeLog

> I assumed that only the corrections would be versioned, and the full
> file would only appear in tarballs as a generated file.

Stefan indicated long ago that this was too drastic, and that we should 
keep ChangeLog history files in the repository, e.g., lisp/ChangeLog.10 
is still in the repository and hasn't changed since January 1's 
copyright-date edits.  ChangeLog.1 is another file like 
lisp/ChangeLog.10; i.e., it's another versioned ChangeLog history file 
that you can edit by hand whenever you like.

> I further assumed that the new-style generated log would always be
> separate from the old-style ChangeLog.1

Yes, that's correct.  The ChangeLog file in the tarball (built by 'make 
ChangeLog') is disjoint from ChangeLog.1, in that ChangeLog.1 contains 
only "older" entries and Changelog contains only "newer" entries.

> (I thought this was why the
> latter was renamed to ChangeLog.1), but it seems like you added new
> entries to ChangeLog.1?

Yes, the idea is that you can move the boundary line between "older" and 
"newer" by running "make change-history".  This automated procedure 
moves the boundary to be the present, and hence entries that until now 
would have been put into ChangeLog, are put into ChangeLog.1 and become 
part of the manually-edited history, which means that ChangeLog will 
become empty.  This is how you can fix old ChangeLog entries: run "make 
change-history", then edit ChangeLog.1 by hand and commit the result.

The advantage of this approach over the old Emacs approach, is that 
ordinary commits won't alter any ChangeLog files, which will make merge 
collisions less common.  (RMS's recent problem, for example, would have 
not occurred.)  And the advantage of this approach over the approach 
taken by Coreutils, Grep, etc. (which do not store ChangeLogs in the 
repository) is that it's easier to edit history by hand.  In effect, we 
have a hybrid approach, which uses Coreutils style for "recent" 
changelog entries and traditional Emacs style for "older" changelog entries.