Re: [PATCH] Add "list" and "rm" sub commands to tg-depend

Hello,

On Thu, Apr 09, 2009 at 08:01:04PM +0200, Bert Wesarg wrote:

2009/4/9 Ira Weiny [off-list ref]:

quoted

On Thu, 9 Apr 2009 14:43:37 +0200
Uwe Kleine-König [off-list ref] wrote:

quoted

You might want to check

      http:// thread.gmane.org/gmane.comp.version-control.git/114581

Ah this brings up more issues I had not thought about...  :-(  But perhaps
Bert's work could be used to help implement "rm".  Thoughts?

No, it wont help. Because the base and tip of the topic should not
changed in respect to the old state (expect for .topdeps of course).

If you really want to remove a dependency, you need to revert a merge
of this dep from the topic base. which is not possible today, or maybe
I have just an idea for this:

  'topic': the topic
  'base':  the base of the topic, i.e. a merge from all dependent
topics dep0, ..., depN

say you want to remove dep0

  1) merge all deps dep1, ..,depN into 'new-base'

  2) merge 'new-base' into base with the merge driver 'theirs', that
would overwrite all changes from dep0 in the 'base'

  3) update 'topic' to the updated 'base'

Any thoughts from someone who knows more than me?

Some time ago I thought about a similar issue:

I based a branch on top of the Linux tree of the ARM maintainer (in the
following called "rmk") and decided later to base it on top of Linus'
tree.  So I did ~:

	git checkout refs/top-bases/$branch
	git merge -s theirs linus/master
	git checkout $branch
	sed -i s,rmk,linus, .topdeps
	git add -f .topdeps
	git commit -m $commitmsg
	tg update

When I thought about it with pencil and paper back then, I saw a problem
with that approach.  Now I invested some time now to verify it really
exists:  In fact I reverted the changes in the rmk/master branch.
Consider Linus pulls from rmk and I update my topgit branch.  Guess what
happens?  Linus' pull + my revert yield Linus' tree without rmk's
changes.

Here is my recipe:

	# prepare linus/master
	git init
	echo 'VERSION=2.6.28' > Makefile
	git add Makefile; git commit -m 'v2.6.28'
	git branch -m master linus/master

	# prepare rmk/master
	git checkout -b rmk/master
	echo 'support for some machine' > arm.c
	git add arm.c; git commit -m 'support for some machine'

	# new topgit branch
	tg create t/test
	echo change > lib.c
	git add lib.c; git commit -m 'tralala'

	# Linus goes on ...
	git checkout linus/master
	echo 'VERSION=2.6.29-rc1' > Makefile
	git add Makefile; git commit -m 'v2.6.29-rc1'

	# "rebase" test branch on linus/master
	git checkout refs/top-bases/t/test
	git symbolic-ref HEAD refs/top-bases/t/test
	git merge --no-commit linus/master
	git read-tree linus/master
	git commit
	rm arm.c
	git checkout t/test
	sed -i s/rmk/linus/ .topdeps
	git add .topdeps; git commit -m 'change dep: rmk/master -> linus/master'
	tg update

	# Linus pulls from rmk
	git checkout linus/master
	git merge rmk/master

	# update test to linus+rmk
	git checkout t/test
	tg update

	# inspect:
	git diff linus/master refs/top-bases/t/test

The last command shows that refs/top-bases/t/test doesn't have arm.c
:-/

I'm sure the dependency deletion has exactly the same problem.

Best regards
Uwe

-- 
Pengutronix e.K.                              | Uwe Kleine-König            |
Industrial Linux Solutions                    | http://www.pengutronix.de/  |