filter-branch: nearest-ancestor rewriting outside subdir filter

Since a0e4639 (filter-branch: fix ref rewriting with
--subdirectory-filter, 2008-08-12) git-filter-branch has done
nearest-ancestor rewriting when using a --subdirectory-filter.

However, that rewriting strategy is also a useful building block in
other tasks.  For example, if you want to split out a subset of files
from your history, you would typically call

  git filter-branch -- <refs> -- <files>

But this fails for all refs that do not point directly to a commit
that affects <files>, because their referenced commit will not be
rewritten and the ref remains untouched.

The code was already there for the --subdirectory-filter case, so just
introduce an option that enables it independently.

Signed-off-by: Thomas Rast <trast@student.ethz.ch>
Signed-off-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 18 insertions, 0 deletions

diff --git a/t/t7003-filter-branch.sh b/t/t7003-filter-branch.sh
index 329c851685..9503875e97 100755
--- a/t/t7003-filter-branch.sh
+++ b/t/t7003-filter-branch.sh
@@ -288,4 +288,22 @@ test_expect_success 'Prune empty commits' '
 	test_cmp expect actual
 '
 
+test_expect_success '--remap-to-ancestor with filename filters' '
+	git checkout master &&
+	git reset --hard A &&
+	test_commit add-foo foo 1 &&
+	git branch moved-foo &&
+	test_commit add-bar bar a &&
+	git branch invariant &&
+	orig_invariant=$(git rev-parse invariant) &&
+	git branch moved-bar &&
+	test_commit change-foo foo 2 &&
+	git filter-branch -f --remap-to-ancestor \
+		moved-foo moved-bar A..master \
+		-- -- foo &&
+	test $(git rev-parse moved-foo) = $(git rev-parse moved-bar) &&
+	test $(git rev-parse moved-foo) = $(git rev-parse master^) &&
+	test $orig_invariant = $(git rev-parse invariant)
+'
+
 test_done