[PATCH 2/3] filter-branch: fix ref rewriting with --subdirectory-filter
The previous ancestor discovery code failed on any refs that are (pre-rewrite) ancestors of commits marked for rewriting. This means that in a situation
A -- B(topic) -- C(master)
where B is dropped by --subdirectory-filter pruning, the 'topic' was not moved up to A as intended, but left unrewritten because we asked about 'git rev-list ^master topic', which does not return anything.
Instead, we use the straightforward
git rev-list -1 $ref -- $filter_subdir
to find the right ancestor. To justify this, note that the nearest ancestor is unique: We use the output of
git rev-list --parents -- $filter_subdir
to rewrite commits in the first pass, before any ref rewriting. If B is a non-merge commit, the only candidate is its parent. If it is a merge, there are two cases:
- All sides of the merge bring the same subdirectory contents. Then
rev-list already pruned away the merge in favour for just one of its
parents, so there is only one candidate.
- Some merge sides, or the merge outcome, differ. Then the merge is
not pruned and can be rewritten directly.
So it is always safe to use rev-list -1.
Signed-off-by: Thomas Rast <trast@student.ethz.ch>
---
git-filter-branch.sh | 27 +++++++++++----------------
t/t7003-filter-branch.sh | 2 +-
2 files changed, 12 insertions(+), 17 deletions(-)
Show changes to 2 files +12 −17
git-filter-branch.sh, t/t7003-filter-branch.sh
diff --git a/git-filter-branch.sh b/git-filter-branch.sh
index a324cf0..a140337 100755
--- a/git-filter-branch.sh
+++ b/git-filter-branch.sh
@@ -317,24 +317,19 @@ done <../revs
# In case of a subdirectory filter, it is possible that a specified head
# is not in the set of rewritten commits, because it was pruned by the
-# revision walker. Fix it by mapping these heads to the next rewritten
-# ancestor(s), i.e. the boundaries in the set of rewritten commits.
+# revision walker. Fix it by mapping these heads to the unique nearest
+# ancestor that survived the pruning.
-# NEEDSWORK: we should sort the unmapped refs topologically first
-while read ref
-do
- sha1=$(git rev-parse "$ref"^0)
- test -f "$workdir"/../map/$sha1 && continue
- # Assign the boundarie(s) in the set of rewritten commits
- # as the replacement commit(s).
- # (This would look a bit nicer if --not --stdin worked.)
- for p in $( (cd "$workdir"/../map; ls | sed "s/^/^/") |
- git rev-list $ref --boundary --stdin |
- sed -n "s/^-//p")
+if test "$filter_subdir"
+then
+ while read ref
do
- map $p >> "$workdir"/../map/$sha1
- done
-done < "$tempdir"/heads
+ sha1=$(git rev-parse "$ref"^0)
+ test -f "$workdir"/../map/$sha1 && continue
+ ancestor=$(git rev-list -1 $ref -- "$filter_subdir")
+ test "$ancestor" && echo $(map $ancestor) >> "$workdir"/../map/$sha1
+ done < "$tempdir"/heads
+fi
# Finally update the refs
diff --git a/t/t7003-filter-branch.sh b/t/t7003-filter-branch.sh
index 4382baa..233254f 100755
--- a/t/t7003-filter-branch.sh
+++ b/t/t7003-filter-branch.sh
@@ -101,7 +101,7 @@ test_expect_success 'filter subdirectory only' '
refs/heads/sub refs/heads/sub-earlier
'
-test_expect_failure 'subdirectory filter result looks okay' '
+test_expect_success 'subdirectory filter result looks okay' '
test 2 = $(git rev-list sub | wc -l) &&
git show sub:new &&
test_must_fail git show sub:subdir &&
--
1.6.0.rc2.30.gb6bda
Thomas Rast