From 49ec402d52dc8f8e55e62537c95766b623e63d6b Mon Sep 17 00:00:00 2001 From: Paul Tan Date: Thu, 18 Jun 2015 18:54:06 +0800 Subject: [PATCH] pull: implement pulling into an unborn branch b4dc085 (pull: merge into unborn by fast-forwarding from empty tree, 2013-06-20) established git-pull's current behavior of pulling into an unborn branch by fast-forwarding the work tree from an empty tree to the merge head, then setting HEAD to the merge head. Re-implement this behavior by introducing pull_into_void() which will be called instead of run_merge() if HEAD is invalid. Helped-by: Stephen Robin Signed-off-by: Paul Tan Signed-off-by: Junio C Hamano --- builtin/pull.c | 29 ++++++++++++++++++++++++++++- 1 file changed, 28 insertions(+), 1 deletion(-) diff --git a/builtin/pull.c b/builtin/pull.c index 110e719481..492bb0e28c 100644 --- a/builtin/pull.c +++ b/builtin/pull.c @@ -13,6 +13,7 @@ #include "sha1-array.h" #include "remote.h" #include "dir.h" +#include "refs.h" static const char * const pull_usage[] = { N_("git pull [options] [ [...]]"), @@ -367,6 +368,27 @@ static int run_fetch(const char *repo, const char **refspecs) return ret; } +/** + * "Pulls into void" by branching off merge_head. + */ +static int pull_into_void(const unsigned char *merge_head, + const unsigned char *curr_head) +{ + /* + * Two-way merge: we treat the index as 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. + */ + if (checkout_fast_forward(EMPTY_TREE_SHA1_BIN, merge_head, 0)) + return 1; + + if (update_ref("initial pull", "HEAD", merge_head, curr_head, 0, UPDATE_REFS_DIE_ON_ERR)) + return 1; + + return 0; +} + /** * Runs git-merge, returning its exit status. */ @@ -476,5 +498,10 @@ int cmd_pull(int argc, const char **argv, const char *prefix) if (!merge_heads.nr) die_no_merge_candidates(repo, refspecs); - return run_merge(); + if (is_null_sha1(orig_head)) { + if (merge_heads.nr > 1) + die(_("Cannot merge multiple branches into empty head.")); + return pull_into_void(*merge_heads.sha1, curr_head); + } else + return run_merge(); }