From 172b6428d06ff4eb0812f087a497d50b6c878fe1 Mon Sep 17 00:00:00 2001
From: Clemens Buchacher <drizzd@aon.at>
Date: Sun, 14 Nov 2010 23:07:49 +0100
Subject: [PATCH] do not overwrite untracked during merge from unborn branch
In case HEAD does not point to a valid commit yet, merge is
implemented as a hard reset. This will cause untracked files to be
overwritten.
Instead, assume the empty tree for HEAD and do a regular merge. An
untracked file will cause the merge to abort and do nothing. If no
conflicting files are present, the merge will have the same effect
as a hard reset.
Signed-off-by: Clemens Buchacher <drizzd@aon.at>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
builtin/merge.c | 20 +++++++++++++++++++-
t/t7607-merge-overwrite.sh | 16 ++++++++++++++++
2 files changed, 35 insertions(+), 1 deletion(-)
diff --git a/builtin/merge.c b/builtin/merge.c
index 37ce4f589f6..2a6c49f6ce4 100644
--- a/builtin/merge.c
+++ b/builtin/merge.c
@@ -231,6 +231,24 @@ static void save_state(void)
die("not a valid object: %s", buffer.buf);
}
+static void read_empty(unsigned const char *sha1, int verbose)
+{
+ int i = 0;
+ const char *args[7];
+
+ args[i++] = "read-tree";
+ if (verbose)
+ args[i++] = "-v";
+ args[i++] = "-m";
+ args[i++] = "-u";
+ args[i++] = EMPTY_TREE_SHA1_HEX;
+ args[i++] = sha1_to_hex(sha1);
+ args[i] = NULL;
+
+ if (run_command_v_opt(args, RUN_GIT_CMD))
+ die("read-tree failed");
+}
+
static void reset_hard(unsigned const char *sha1, int verbose)
{
int i = 0;
@@ -979,7 +997,7 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
die("%s - not something we can merge", argv[0]);
update_ref("initial pull", "HEAD", remote_head->sha1, NULL, 0,
DIE_ON_ERR);
- reset_hard(remote_head->sha1, 0);
+ read_empty(remote_head->sha1, 0);
return 0;
} else {
struct strbuf merge_names = STRBUF_INIT;
diff --git a/t/t7607-merge-overwrite.sh b/t/t7607-merge-overwrite.sh
index 49f4e1599ac..8317a574ce2 100755
--- a/t/t7607-merge-overwrite.sh
+++ b/t/t7607-merge-overwrite.sh
@@ -84,4 +84,20 @@ test_expect_success 'will not overwrite removed file with staged changes' '
test_cmp important c1.c
'
+cat >expect <<\EOF
+error: Untracked working tree file 'c0.c' would be overwritten by merge.
+fatal: read-tree failed
+EOF
+
+test_expect_success 'will not overwrite untracked file on unborn branch' '
+ git reset --hard c0 &&
+ git rm -fr . &&
+ git checkout --orphan new &&
+ cp important c0.c &&
+ test_must_fail git merge c0 2>out &&
+ test_cmp out expect &&
+ test_path_is_missing .git/MERGE_HEAD &&
+ test_cmp important c0.c
+'
+
test_done