fast-export: fix regression skipping some merge-commits

7199203937 (object_array: add and use `object_array_pop()`, 2017-09-23)
noted that the pattern `object = array.objects[--array.nr].item` could
be abstracted as `object = object_array_pop(&array)`.

Unfortunately, one of the conversions was horribly wrong. Between
grabbing the last object (i.e., peeking at it) and decreasing the object
count, the original code would sometimes return early. The updated code
on the other hand, will always pop the last element, then maybe do the
early return without doing anything with the object.

The end result is that merge commits where all the parents have still
not been exported will simply be dropped, meaning that they will be
completely missing from the exported data.

Re-add a commit when it is not yet time to handle it. An alternative
that was considered was to peek-then-pop. That carries some risk with it
since the peeking and popping need to act on the same object, in a
concerted fashion.

Add a test that would have caught this.

Reported-by: Isaac Chou <Isaac.Chou@microfocus.com>
Analyzed-by: Isaac Chou <Isaac.Chou@microfocus.com>
Helped-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: Martin Ågren <martin.agren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin/fast-export.c b/builtin/fast-export.c
index 796d0cd66c7750a20613dea77cd75b1b8e7665a4..2fc3e768356a55b4e94580f01875d45044e41998 100644 (file)
--- a/builtin/fast-export.c
+++ b/builtin/fast-export.c
@@ -651,8 +651,11 @@ static void handle_tail(struct object_array *commits, struct rev_info *revs,
        struct commit *commit;
        while (commits->nr) {
                commit = (struct commit *)object_array_pop(commits);
-               if (has_unshown_parent(commit))
+               if (has_unshown_parent(commit)) {
+                       /* Queue again, to be handled later */
+                       add_object_array(&commit->object, NULL, commits);
                        return;
+               }
                handle_commit(commit, revs, paths_of_changed_objects);
        }
 }

diff --git a/t/t9350-fast-export.sh b/t/t9350-fast-export.sh
index 866ddf60581e3fea1afdbe28e71e7f3137da5722..c699c88d00d3bb80a290025d481517742e6f1cb1 100755 (executable)
--- a/t/t9350-fast-export.sh
+++ b/t/t9350-fast-export.sh
@@ -540,4 +540,22 @@ test_expect_success 'when using -C, do not declare copy when source of copy is a
        test_cmp expected actual
 '
 
+test_expect_success 'merge commit gets exported with --import-marks' '
+       test_create_repo merging &&
+       (
+               cd merging &&
+               test_commit initial &&
+               git checkout -b topic &&
+               test_commit on-topic &&
+               git checkout master &&
+               test_commit on-master &&
+               test_tick &&
+               git merge --no-ff -m Yeah topic &&
+
+               echo ":1 $(git rev-parse HEAD^^)" >marks &&
+               git fast-export --import-marks=marks master >out &&
+               grep Yeah out
+       )
+'
+
 test_done