From b4dc085a8dc2ec2fb5f6366fa672222b807ed655 Mon Sep 17 00:00:00 2001 From: Thomas Rast Date: Thu, 20 Jun 2013 18:38:28 -0400 Subject: [PATCH] pull: merge into unborn by fast-forwarding from empty tree MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit The logic for pulling into an unborn branch was originally designed to be used on a newly-initialized repository (d09e79c, git-pull: allow pulling into an empty repository, 2006-11-16). It thus did not initially deal with uncommitted changes in the unborn branch. The case of an _unstaged_ untracked file was fixed by 4b3ffe5 (pull: do not clobber untracked files on initial pull, 2011-03-25). However, it still clobbered existing staged files, both when the file exists in the merged commit (it will be overwritten), and when it does not (it will be deleted). We fix this by doing a two-way merge, where the "current" side of the merge is an empty tree, and the "target" side is HEAD (already updated to FETCH_HEAD at this point). This amounts to claiming that all work in the index was done vs. an empty tree, and thus all content of the index is precious. Note that this use of read-tree just gives us protection against overwriting index and working tree changes. It will not actually result in a 3-way merge conflict in the index. This is fine, as this is a rare situation, and the conflict would not be interesting anyway (it must, by definition, be an add/add conflict with the whole content conflicting). And it makes it simpler for the user to recover, as they have no HEAD to "git reset" back to. Reported-by: Stefan Schüßler Signed-off-by: Thomas Rast Signed-off-by: Jeff King Signed-off-by: Junio C Hamano --- git-pull.sh | 9 ++++++++- t/t5520-pull.sh | 29 +++++++++++++++++++++++++++++ 2 files changed, 37 insertions(+), 1 deletion(-) diff --git a/git-pull.sh b/git-pull.sh index f323f56bcb..2c502171f7 100755 --- a/git-pull.sh +++ b/git-pull.sh @@ -260,9 +260,16 @@ case "$merge_head" in ;; esac +# Pulling into unborn branch: a shorthand for branching off +# FETCH_HEAD, for lazy typers. if test -z "$orig_head" then - git read-tree -m -u $merge_head && + # Two-way merge: we claim the index is based on an empty tree, + # and try to fast-forward to HEAD. This ensures we will not + # lose index/worktree changes that the user already made on + # the unborn branch. + empty_tree=4b825dc642cb6eb9a060e54bf8d69288fbee4904 + git read-tree -m -u $empty_tree $merge_head && git update-ref -m "initial pull" HEAD $merge_head "$curr_head" exit fi diff --git a/t/t5520-pull.sh b/t/t5520-pull.sh index 35304b41e9..dd24b0cdbb 100755 --- a/t/t5520-pull.sh +++ b/t/t5520-pull.sh @@ -57,6 +57,35 @@ test_expect_success 'pulling into void does not overwrite untracked files' ' ) ' +test_expect_success 'pulling into void does not overwrite staged files' ' + git init cloned-staged-colliding && + ( + cd cloned-staged-colliding && + echo "alternate content" >file && + git add file && + test_must_fail git pull .. master && + echo "alternate content" >expect && + test_cmp expect file && + git cat-file blob :file >file.index && + test_cmp expect file.index + ) +' + + +test_expect_success 'pulling into void does not remove new staged files' ' + git init cloned-staged-new && + ( + cd cloned-staged-new && + echo "new tracked file" >newfile && + git add newfile && + git pull .. master && + echo "new tracked file" >expect && + test_cmp expect newfile && + git cat-file blob :newfile >newfile.index && + test_cmp expect newfile.index + ) +' + test_expect_success 'test . as a remote' ' git branch copy master && -- 2.11.4.GIT