rebase: implement --[no-]autostash and rebase.autostash

This new feature allows a rebase to be executed on a dirty worktree or
index.  It works by creating a temporary "dangling merge commit" out
of the worktree and index changes (via 'git stash create'), and
automatically applying it after a successful rebase or abort.

rebase stores the SHA-1 hex of the temporary merge commit, along with
the rest of the rebase state, in either
.git/{rebase-merge,rebase-apply}/autostash depending on the kind of
rebase.  Since $state_dir is automatically removed at the end of a
successful rebase or abort, so is the autostash.

The advantage of this approach is that we do not affect the normal
stash's reflogs, making the autostash invisible to the end-user.  This
means that you can use 'git stash' during a rebase as usual.

When the autostash application results in a conflict, we push
$state_dir/autostash onto the normal stash and remove $state_dir
ending the rebase.  The user can inspect the stash, and pop or drop at
any time.

Most significantly, this feature means that a caller like pull (with
pull.rebase set to true) can easily be patched to remove the
require_clean_work_tree restriction.

Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 148 insertions, 0 deletions

diff --git a/t/t3420-rebase-autostash.sh b/t/t3420-rebase-autostash.sh
new file mode 100755
index 0000000000..479cbb215f
--- /dev/null
+++ b/t/t3420-rebase-autostash.sh
@@ -0,0 +1,148 @@
+#!/bin/sh
+#
+# Copyright (c) 2013 Ramkumar Ramachandra
+#
+
+test_description='git rebase --autostash tests'
+. ./test-lib.sh
+
+test_expect_success setup '
+	echo hello-world >file0 &&
+	git add . &&
+	test_tick &&
+	git commit -m "initial commit" &&
+	git checkout -b feature-branch &&
+	echo another-hello >file1 &&
+	echo goodbye >file2 &&
+	git add . &&
+	test_tick &&
+	git commit -m "second commit" &&
+	echo final-goodbye >file3 &&
+	git add . &&
+	test_tick &&
+	git commit -m "third commit" &&
+	git checkout -b unrelated-onto-branch master &&
+	echo unrelated >file4 &&
+	git add . &&
+	test_tick &&
+	git commit -m "unrelated commit" &&
+	git checkout -b related-onto-branch master &&
+	echo conflicting-change >file2 &&
+	git add . &&
+	test_tick &&
+	git commit -m "related commit"
+'
+
+testrebase() {
+	type=$1
+	dotest=$2
+
+	test_expect_success "rebase$type: dirty worktree, non-conflicting rebase" '
+		test_config rebase.autostash true &&
+		git reset --hard &&
+		git checkout -b rebased-feature-branch feature-branch &&
+		test_when_finished git branch -D rebased-feature-branch &&
+		echo dirty >>file3 &&
+		git rebase$type unrelated-onto-branch &&
+		grep unrelated file4 &&
+		grep dirty file3 &&
+		git checkout feature-branch
+	'
+
+	test_expect_success "rebase$type: dirty index, non-conflicting rebase" '
+		test_config rebase.autostash true &&
+		git reset --hard &&
+		git checkout -b rebased-feature-branch feature-branch &&
+		test_when_finished git branch -D rebased-feature-branch &&
+		echo dirty >>file3 &&
+		git add file3 &&
+		git rebase$type unrelated-onto-branch &&
+		grep unrelated file4 &&
+		grep dirty file3 &&
+		git checkout feature-branch
+	'
+
+	test_expect_success "rebase$type: conflicting rebase" '
+		test_config rebase.autostash true &&
+		git reset --hard &&
+		git checkout -b rebased-feature-branch feature-branch &&
+		test_when_finished git branch -D rebased-feature-branch &&
+		echo dirty >>file3 &&
+		test_must_fail git rebase$type related-onto-branch &&
+		test_path_is_file $dotest/autostash &&
+		! grep dirty file3 &&
+		rm -rf $dotest &&
+		git reset --hard &&
+		git checkout feature-branch
+	'
+
+	test_expect_success "rebase$type: --continue" '
+		test_config rebase.autostash true &&
+		git reset --hard &&
+		git checkout -b rebased-feature-branch feature-branch &&
+		test_when_finished git branch -D rebased-feature-branch &&
+		echo dirty >>file3 &&
+		test_must_fail git rebase$type related-onto-branch &&
+		test_path_is_file $dotest/autostash &&
+		! grep dirty file3 &&
+		echo "conflicting-plus-goodbye" >file2 &&
+		git add file2 &&
+		git rebase --continue &&
+		test_path_is_missing $dotest/autostash &&
+		grep dirty file3 &&
+		git checkout feature-branch
+	'
+
+	test_expect_success "rebase$type: --skip" '
+		test_config rebase.autostash true &&
+		git reset --hard &&
+		git checkout -b rebased-feature-branch feature-branch &&
+		test_when_finished git branch -D rebased-feature-branch &&
+		echo dirty >>file3 &&
+		test_must_fail git rebase$type related-onto-branch &&
+		test_path_is_file $dotest/autostash &&
+		! grep dirty file3 &&
+		git rebase --skip &&
+		test_path_is_missing $dotest/autostash &&
+		grep dirty file3 &&
+		git checkout feature-branch
+	'
+
+	test_expect_success "rebase$type: --abort" '
+		test_config rebase.autostash true &&
+		git reset --hard &&
+		git checkout -b rebased-feature-branch feature-branch &&
+		test_when_finished git branch -D rebased-feature-branch &&
+		echo dirty >>file3 &&
+		test_must_fail git rebase$type related-onto-branch &&
+		test_path_is_file $dotest/autostash &&
+		! grep dirty file3 &&
+		git rebase --abort &&
+		test_path_is_missing $dotest/autostash &&
+		grep dirty file3 &&
+		git checkout feature-branch
+	'
+
+	test_expect_success "rebase$type: non-conflicting rebase, conflicting stash" '
+		test_config rebase.autostash true &&
+		git reset --hard &&
+		git checkout -b rebased-feature-branch feature-branch &&
+		test_when_finished git branch -D rebased-feature-branch &&
+		echo dirty >file4 &&
+		git add file4 &&
+		git rebase$type unrelated-onto-branch &&
+		test_path_is_missing $dotest &&
+		git reset --hard &&
+		grep unrelated file4 &&
+		! grep dirty file4 &&
+		git checkout feature-branch &&
+		git stash pop &&
+		grep dirty file4
+	'
+}
+
+testrebase "" .git/rebase-apply
+testrebase " --merge" .git/rebase-merge
+testrebase " --interactive" .git/rebase-merge
+
+test_done