[gentoo-dev] [RFC] git.eclass, git-2.eclass... git-r1.eclass?

[Michał Górny]

Hello, all.

I think I'm finally ready to put all the breaking awesomeness that was
waiting for the git eclasses. However, I'm wondering what's the best
way of proceeding with it.

We've just lately finished the git->git-2 eclass migration. The old
eclass is no longer used and is marked for removal in a few days.

The new eclass is supposedly used by 732 in-tree packages [1],
and possibly a few dozens out-of-the-tree. Some parts of the eclass API
are barely used. I would really prefer to avoid yet another eclass
migration.

[1]:http://qa-reports.gentoo.org/output/eclass-usage/


However, I would like to do a few breaking changes to simplify
the eclass and its maintenance:

1. Make EGIT_SOURCEDIR default to ${WORKDIR}/${P} rather than ${S}
   (to support setting S to subdirectory of git repo),

2. Kill EGIT_HAS_SUBMODULES and autodetect submodules,

3. Kill EGIT_OPTIONS since it limits the possibility of changing eclass
   code,

4. Kill EGIT_MASTER (it's more trouble than benefit),

5. Possibly kill EGIT_PROJECT -- it won't be good enough anymore,

6. Kill EGIT_NONBARE and support bare checkouts only. Supporting two
   different layouts introduces a lot redundant code.

7. Kill EGIT_NOUNPACK -- possibly replace it with proper fetching
   function, or just src_fetch(),

8. Kill EGIT_DIR -- it supposedly should not even be overriden.


But it's not all removing. There are also a few things I would like to
change/add:

1. Replace 'git clone' with 'git init' + 'git fetch' that would be
   a bit simpler,

2. Add complete & working support for shallow clones, and make it the
   default. This means a lot of space-saving for people who only use
   the repos for ebuilds.

3. Add complete & proper support for submodules. Currently, submodules
   enforce non-bare clones and are fetched during unpack. After
   the change, they will be fetched and unpacked like normal repos.


The use of API features in *.ebuild maps like the following;

EGIT_REPO_URI	521
EGIT_BRANCH	66
EGIT_SOURCEDIR	21
EGIT_PROJECT	17
EGIT_HAS_SUBMODULES	15
EGIT_COMMIT	12
EGIT_BOOTSTRAP	12
EGIT_MASTER	7
EGIT_NOUNPACK	2
EGIT_STORE_DIR	1
EGIT_NONBARE	1
EGIT_DIR	1
EVCS_OFFLINE	0 // these are for make.conf
EGIT_REPACK	0
EGIT_PRUNE	0
EGIT_OPTIONS	0

I will need to take a look which of those cases can be replaced easily.


How should I proceed? Assuming that git-2.eclass is used by live
ebuilds only, and those ebuilds can be subject to random breakage,
I could supposedly just start changing API of the eclass.

On the other hand, I could also go for beautiful git-r1.eclass,
and cleanly switch the packages.

Then, I could go for something involving the two -- create a new
git-r1.eclass that has API fully stripped, and start deprecating
features from git-2.eclass. We would be able to switch to git-r1 to
test offending packages safely, then do a big switch of remaining
packages and make the two eclasses temporarily equivalent.

What are your thoughts?

-- 
Best regards,
Michał Górny