diff --git a/builtin/pull.c b/builtin/pull.c index 110e71948..492bb0e28 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(); }