Use rev-list --simplify-merges everywhere. This changes the behaviour
of --subdirectory-filter in cases such as
O -- A -\
\ \
\- B -- M
where A and B bring the same changes to the subdirectory: It now keeps
both sides of the merge. Previously, the history would have been
simplified to 'O -- A'. Merges of unrelated side histories that never
touch the subdirectory are still removed.
Signed-off-by: Thomas Rast <trast@xxxxxxxxxxxxxxx>
---
This obviously depends on --simplify-merges which is only in 'next'.
Junio C Hamano wrote:
>
> Perhaps --full-history is needed to the rev-list call (and the recent
> invention --simplify-merges that will hopefully appear sometime after
> 1.6.0)? See recent discussion of --full-history and the default merge
> simplification between Linus and Roman Zippel.
Following history pointers, it turns out the discussion surrounding
a17171b4 (Revert "filter-branch: subdirectory filter needs
--full-history") actually mentions that a simplification step on top
of --full-history is needed:
Junio C Hamano wrote:
[http://kerneltrap.org/mailarchive/git/2007/6/13/249107]
> In short,
> you will end up with something like this:
>
> .---. (side branch)
> / \
> ---A---B---C (merge)
>
> The "merge clean-up" would conceptually be a simple operation.
> Whenever you see a merge C, you look at its parents A and B, and
> cull the ones that are reachable from other parents. You notice
> that A is an ancestor of B, drop A from the parents of C, and
> simplify the above down to:
>
> ---A---B---C (not-a-merge)
Well, turns out that's what you did with --simplify-merges, so let's
use it.
git-filter-branch.sh | 7 ++++---
1 files changed, 4 insertions(+), 3 deletions(-)
diff --git a/git-filter-branch.sh b/git-filter-branch.sh
index 539b2e6..60f64ac 100755
--- a/git-filter-branch.sh
+++ b/git-filter-branch.sh
@@ -239,11 +239,11 @@ mkdir ../map || die "Could not create map/ directory"
case "$filter_subdir" in
"")
git rev-list --reverse --topo-order --default HEAD \
- --parents "$@"
+ --parents --simplify-merges "$@"
;;
*)
git rev-list --reverse --topo-order --default HEAD \
- --parents "$@" -- "$filter_subdir"
+ --parents --simplify-merges "$@" -- "$filter_subdir"
esac > ../revs || die "Could not get the commits"
commits=$(wc -l <../revs | tr -d " ")
@@ -333,7 +333,8 @@ then
do
sha1=$(git rev-parse "$ref"^0)
test -f "$workdir"/../map/$sha1 && continue
- ancestor=$(git rev-list -1 $ref -- "$filter_subdir")
+ ancestor=$(git rev-list --simplify-merges -1 \
+ $ref -- "$filter_subdir")
test "$ancestor" && echo $(map $ancestor) >> "$workdir"/../map/$sha1
done < "$tempdir"/heads
fi
--
1.6.0.rc2.29.g7ec81
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