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#
# git-ffqrebase start [BASE]
# # records previous HEAD so it can be overwritten
# # records base for future git-ffqrebase
# git-ffqrebase set-base BASE
# git-ffqrebase <git-rebase options>
# git-ffqrebase finish
# git-ffqrebase status [BRANCH]
#
# refs/ffq-prev/REF relates to refs/REF
#
# git-debrebase without start, if already started, is willing
# to strip pseudomerges provided that they overwrite exactly
# the previous HEAD
# xxxx is this right ? what matters is have we pushed
# I think in fact the right answer is:
# git-debrebase always strips out pseudomerges from its branch
# a pseudomerge is put in at the time we want to push
# at that time, we make a pseudomerge of the remote tracking
# branch (if raw git) or the dgit view (if dgit)
# for raw git git-ffqrebase, do want preciseley to record
# value of remote tracking branch or our branch, on start, so we
# overwrite only things we intend to
# the previous pseudomerge check for tags and remote branches ?
=========
special commit tags
overall format
[git-debrebase[ COMMIT-TYPE [ ARGS...]]: PROSE, MORE PROSE]
[git-debrebase: split mixed commit, debian part]
[git-debrebase: split mixed commit, upstream-part]
[git-debrebase: convert dgit import, debian changes]
[git-debrebase breakwater: convert dgit import, upstream changes]
[git-debrebase upstream-combine . PIECE[ PIECE...]: new upstream]
[git-debrebase breakwater: new upstream NEW-UPSTREAM-VERSION, merge]
[git-debrebase: new upstream NEW-UPSTREAM-VERSION, changelog]
[git-debrebase: gbp2debrebase, drop patches]
[git-debrebase breakwater: declare upstream]
m{^\[git-debrebase (?:\w*-)?upstream combine \.((?: $extra_orig_namepart_re)+)\]}
Every breakwater commit must be a merge. In principle, this is not
necessary. After all, we are relying on the
[git-debrebase breakwater: ...]
commit message annotation in "declare" breakwater merges (which
do not have any upstream changes), to distinguish those breakwater
merges from ordinary pseudomerges (which we might just try to strip).
However, the user is going to be doing git-rebase a lot. We really
don't want them to rewrite a breakwater base commit. git-rebase
trips up on merges, so that is a useful safety catch.
=========
workflow
git-debrebase blah [implies start] strips pseudomerge(s)
commit / git-debrebase / etc.
dgit --damp-run push
hook: call git-debrebase prep-push adds new pm ? passes --overwrite ?
dgit push does not update remote
commit / git-debrebase / etc. strips pm(s) including last one
dgit push
hook: call git-debrebase prep-push adds new pm ? passes --overwrite ?
dgit push DOES update remote
commit / git-debrebase / etc. strips last pm, but arranges
that remade pm will incorporate it
Aha!
When we strip a pm, we need to maybe record it (or something) as the
new start point.
We do this if the pm is contained within the output branch.
Actually this is not special to PMs.
We need to record a new to-be-overwritten commit
merge-base( our branch tip, relevant remote )
If this is not a descendant of the relevant remote, then we are going
to have a problem when we push so issue a warning or fail.
How about
git-debrebase start or git-debrebase [continue]
with no recorded will-overwrite
putative will-overwrite is
one model:
our current tip
obviously it is safe to say we will overwrite this
we do not need to worry about whether this will
overwrite not-included changes in the remote
because either the will-overwrite is not
ff from the remote (in which case later failure,
see below); or the will-overwrite _is_ ff
from the remote ie our tip is later than the
remote and includes all of its changes
this model tends to keep ad-hoc commits made on our
tip branch before we did rebase start, in the
`interchange view' and also in the rebase stack.
other model:
merge-base( current remote, current tip )
it is safe to overwrite current tip, by the
argument above
it is always safe to rewind will-overwrite: all
that does is overwrite _less_ stuff
this is the earliest overwrite we can make that
will be pushable to the remote
in practical terms this can only be ff from the
current remote if it is equal to the current remote;
so what we are actually checking below is that our tip
is ff from the remote. This ought to be true before
the first of our rebases.
this model tends to rewind and rebase ad-hoc commits
made on our tip branch before we did rebase start,
this is better
in any case putative will-overwrite must be ff from remote.
Otherwise when we push it will not be ff, even though we have
made pseudomerge to overwrite will-overwrite. So if we spot
this, report an error.
with a recorded will-overwrite
we may need to advance will-overwrite, to allow us to generate
future pseudomerges that will be pushable
advancing will-overwrite is dangerous, since it might
effectively cancel the commits that will-ovewrite is advanced
over.
we advance it to merge-base( current remote, current tip )
if possible (see above), - ie to current remote, subject
to the condition that that is an ancestor of current tip
In each case we can strip pseudomerges freely, as needed. We do not
want to record what pseudomerges we strip, because whether we need to
keep them depends (only) on whether they have been pushed.
Is that actually true ? What if the user actually _wanted_ to keep
the pseudomerge despite not having pushed it ?
In that case we need to advance will-overwrite past it. We could
provide an explicit command to do this: it would advance
will-overwrite to the current tip (see rules above, which show that
this is OK). Or maybe to the last pseudomerge on the current tip,
so that the overall result will be series of pseudomerges.
========================================
So, pm handling specifics:
strategy is to avoid making needless pseudomerges
pseudomerges that exist will be preserved
(by being included in will-overwrite)
This is good because the presence of a pseudomerge means we know we
want to keep it; and that allows explicit control over history detail
level.
It does mean we must avoid making the pseudomerges unnecessarily.
They should be made just before (ideally, part of) dgit push.
1. git-debrebase [-i etc.]
should:
check for will-overwrite
if is already a will-overwrite, fine, do no more
if not:
check our origin branch exists and we are ff from it
if not fail
check our other might-be-pushed to branches
check we are ff from them
if not fail
set will-overwrite to something which is ff from
all above branches
we use our tip, as discussed above
(optionally, can use some other commit which is ff
from all of the above, eg one of them)
N. git-debrebase [--noop-ok] record-ffq-prev
does what is described above
2. git-debrebase [--noop-ok] stitch
makes pseudomerge with will-overwrite
deletes will-overwrite
we will teach dgit to do
git-debrebase stitch
3. git-debrebase push
like git push only does stitch first
??? command line parsing!
4. git-debrebase release
stiches, finalises changelog, signs tags, pushes everything
for the future, when there is some automatic builder
will-overwrite for each ref
refs/heads/FOO
is
refs/ffq-prev/FOO
========================================
import from gbp
[ all this is done now:
inputs:
current HEAD (patches-unapplied),
this is going to be the base of the old breakwater
nominated upstream
checks:
HEAD:<upstream> = upstream:<upstream>
upstream..HEAD:<upstream> is empty (overrideable)
upstremm:debian is empty (overrideable)
procedure:
construct
run gbp pq import to generate pq branch
new breakwater is
old HEAD
commit to remove d/patches
breakwater pseudomerge with upstream
"rebase" of pq branch, each commit with d/patches stripped
]
what about dgit view branch ?
ideally, would make pseudomerge over dgit view
would need to check that dgit view is actually dgit view of
ond of our ancestors
failing that first push will need --overwrite
should this be called import or gbp2debrebase as it is now ?
gbp uses "import" oddly but I'm tempted to use it normally here.
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