blame: allow to blame paths freshly added to the index

When blaming files, changes in the work tree are taken into account
and displayed as being "Not Committed Yet".

However, when blaming a file that is not known to the current HEAD,
git blame fails with `no such path 'foo' in HEAD`, even when the file
was git add'ed.

Allowing such a blame is useful when the new file added to the index
(not yet committed) was created by renaming an existing file.  It
also is useful when the new file was created from pieces already in
HEAD, moved or copied from other files and blaming with copy
detection (i.e. "-C").

Signed-off-by: Mike Hommey <mh@glandium.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/blame.c

@@ -2230,6 +2230,7 @@ static int git_blame_config(const char *var, const char *value, void *cb)
 static void verify_working_tree_path(struct commit *work_tree, const char *path)
 {
 	struct commit_list *parents;
+	int pos;
 
 	for (parents = work_tree->parents; parents; parents = parents->next) {
 		const unsigned char *commit_sha1 = parents->item->object.oid.hash;
@@ -2240,7 +2241,14 @@ static void verify_working_tree_path(struct commit *work_tree, const char *path)
 		    sha1_object_info(blob_sha1, NULL) == OBJ_BLOB)
 			return;
 	}
-	die("no such path '%s' in HEAD", path);
+
+	pos = cache_name_pos(path, strlen(path));
+	if (pos >= 0)
+		; /* path is in the index */
+	else if (!strcmp(active_cache[-1 - pos]->name, path))
+		; /* path is in the index, unmerged */
+	else
+		die("no such path '%s' in HEAD", path);
 }
 
 static struct commit_list **append_parent(struct commit_list **tail, const unsigned char *sha1)

t/t8003-blame-corner-cases.sh

@@ -137,6 +137,51 @@ test_expect_success 'blame wholesale copy and more' '
 
 '
 
+test_expect_success 'blame wholesale copy and more in the index' '
+
+	cat >horse <<-\EOF &&
+	ABC
+	DEF
+	XXXX
+	YYYY
+	GHIJK
+	EOF
+	git add horse &&
+	test_when_finished "git rm -f horse" &&
+	git blame -f -C -C1 -- horse | sed -e "$pick_fc" >current &&
+	cat >expected <<-\EOF &&
+	mouse-Initial
+	mouse-Second
+	cow-Fifth
+	horse-Not
+	mouse-Third
+	EOF
+	test_cmp expected current
+
+'
+
+test_expect_success 'blame during cherry-pick with file rename conflict' '
+
+	test_when_finished "git reset --hard && git checkout master" &&
+	git checkout HEAD~3 &&
+	echo MOUSE >> mouse &&
+	git mv mouse rodent &&
+	git add rodent &&
+	GIT_AUTHOR_NAME=Rodent git commit -m "rodent" &&
+	git checkout --detach master &&
+	(git cherry-pick HEAD@{1} || test $? -eq 1) &&
+	git show HEAD@{1}:rodent > rodent &&
+	git add rodent &&
+	git blame -f -C -C1 rodent | sed -e "$pick_fc" >current &&
+	cat current &&
+	cat >expected <<-\EOF &&
+	mouse-Initial
+	mouse-Second
+	rodent-Not
+	EOF
+	test_cmp expected current
+'
+
 test_expect_success 'blame path that used to be a directory' '
 	mkdir path &&
 	echo A A A A A >path/file &&