Changelog Chew

SUSE Linux uses the RPM package format. Each RPM has a changelog, normally kept as a %changelog section in its *.spec file. A SUSE specialty is keeping this changelog in a separate *.changes file.

Often this *.changes file is kept in Git, and merge conflicts occur. suse-changelog-merge is a semantic merge tool to help with this.

Installation

~/.gitconfig:

[merge "suse-changelog-merge"]
        name = SUSE .changes merge driver
        driver = /(wherever)/suse-changelog-merge %A %O %B

~/.config/git/attributes:

*.changes       merge=suse-changelog-merge

Features and Limitations

suse-changelog-merge takes 3 arguments: CURRENT, COMMON, OTHER (like merge(1)) and works by taking what was added between COMMON and OTHER, and putting it on top of CURRENT.

Suppose the .changes in the master branch has

-------------------------------------------------------------------
Tue Sep  3 12:00:00 CEST 2013 - ada@example.com

- Implemented the difference engine.

-------------------------------------------------------------------
Mon Sep  2 12:00:00 CEST 2013 - ada@example.com

- Initial packaging.

Suppose we now branch a-feature, with

Friday:    Implemented the differentiation engine.
Tuesday:   Implemented the difference engine.
Monday:    Initial packaging.

and in the meantime master becomes

Wednesday: Implemented two ring machines.
Tuesday:   Implemented the difference engine.
Monday:    Initial packaging.

Merging a-feature into master will work just fine, producing a chronological changelog:

Friday:    Implemented the differentiation engine.
Wednesday: Implemented two ring machines.
Tuesday:   Implemented the difference engine.
Monday:    Initial packaging.

However, merging master into a-feature will produce a conflict:

<<<
===
Wednesday: Implemented two ring machines.
>>>
Friday:    Implemented the differentiation engine.
Tuesday:   Implemented the difference engine.
Monday:    Initial packaging.

This is because the history up to Friday may have been already published in an OBS instance that disallows inserting in the middle of the changelog.

TODO, not implemented yet: we could adjust the Wednesday timestamp to the current time automatically.