Daniel Barkalow wrote:
On Wed, 10 Jan 2007, Junio C Hamano wrote:
Andreas Ericsson <ae@xxxxxx> writes:
... Since committing on
detached heads really should be a very rare case I don't think many
people will find this terribly annoying.
Quite the contrary, I would imagine it would be quite natural to
do throw-away commits and merges on detached head while
bisecting the history (e.g. commit small fixup to make it
compile and then mark the result for bisection to hunt for real
bugs that are hidden by silly compilation problems).
I don't think this would actually work. If you commit your build fix, and
then mark the result as bad, won't bisect skew its choices due to
suspecting that your build fix is the real bug?
I'd think that, if you make changes while bisecting, you probably want to
leave those changes uncommitted, and merge or discard them when testing
other commits.
If anything, I'd think you'd want a rather different sort of commit
mechanism than the usual commit, which says, "whenever you consider commit
{sha1-from-real-history}, use {tree-with-local-changes} instead of
{tree-in-real-commit}." Or, more generally, "in order to get the trees
I want to actually use, this patch (git diff HEAD) needs to be applied to
every commit in some portion of the history including, at least,
get_sha1(HEAD)".
I'm not seeing any actual benefit to causing the history to contain a
dead-end fork off of an antique commit, and then throwing this away. And
committing your change so that it won't get lost, with the intention of
losing it in a little while, doesn't seem to make any sense, either.
Same here. I'd imagine temporary build-fixes to live as a patch-file
generated by
git diff > build-fixes.diff
after having hacked on the tree. There's no sane way of inserting
commits into the middle of the DAG, so committing on something that
isn't a branch with the intention of losing it is just plain weird.
(Of course, it also makes sense to do merges, but again, you probably want
to create and temporarily use the working tree resulting from the merge,
not create the commit.)
Yes. I'd imagine "git merge --no-commit" could be used for this, to
merge things only in the working directory.
I think that the workflow that uses regular commits with a detached HEAD
is this: do a series of commits representing real work on top of a remote
branch or a tag, and decide later (once you've tested the results for
worthiness) whether to turn this into a topic branch or throw it away.
Perhaps, but this is also a bit weird, as you would normally hack things
up to fit on top of some already existing branch, so then you'd detach
the head but point it to something that already has a branch-name
associated with it.
Otoh, I could imagine this would be sort of nifty for applying bugfixes
on top of old tags, so perhaps it's not so weird after all. Then you'd
probably want to create a new tag before releasing the bugfixed version,
so Linus suggestion makes sense in this case (assuming it doesn't fsck
up the bisect case, ofc).
But I don't think this is a good match for detached HEAD, because you may
want to do exactly the same thing, but start with a regular local head. I
think the right thing to do is something like "git checkout --anon", which
puts you on a new branch with no name, which will evaporate if you leave
it (as per "git branch -d"; you need to force it if it isn't fully
merged).
Yes. I'd imagine "git merge --no-commit" could be used for this, to
merge things only in the working directory. We could easily create a
hack for this by doing a "git reset --mixed HEAD^1" after the merge is
complete.
So I think the feature which lets you make commits without being on a
branch from refs/heads is actually a different feature from "detached
HEAD", which only shares the aspect that "git branch" has no line with a
"*", because there is no name for what HEAD points to.
Agreed. They really are two completely different things. I see no harm
in splitting them up codewise. Bisect could start working without its
protected branch straight away, but commits (and merges) to detached
heads wouldn't work at all. Then we can see what use people put this to
and what walls they run into and make the feature accordingly.
--
Andreas Ericsson andreas.ericsson@xxxxxx
OP5 AB www.op5.se
Tel: +46 8-230225 Fax: +46 8-230231
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