rev-list: detect broken root trees

When the traversal machinery sees a commit without a root tree, it assumes that the tree was part of a BOUNDARY commit, and quietly ignores the tree. But it could also be caused by a commit whose root tree is broken or missing. Instead, let's die() when we see a NULL root tree. We can differentiate it from the BOUNDARY case by seeing if the commit was actually parsed. This covers that case, plus future-proofs us against any others where we might try to show an unparsed commit. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Jeff King committed Apr 9, 2019 at 19:13 UTC 97dd512af7ce4afb4f638ef73b4770921c8ca3aa
2 files changed +7 -2
list-objects.c
+3
@@ -374,6 +374,9 @@ static void do_traverse(struct traversal_context *ctx)
374 struct tree *tree = get_commit_tree(commit);
375 tree->object.flags |= NOT_USER_GIVEN;
376 add_pending_tree(ctx->revs, tree);
377 + } else if (commit->object.parsed) {
378 + die(_("unable to load root tree for commit %s"),
379 + oid_to_hex(&commit->object.oid));
380 }
381 ctx->show_commit(commit, ctx->show_data);
382
t/t6102-rev-list-unexpected-objects.sh
+4 -2
@@ -67,8 +67,10 @@ test_expect_success 'traverse unexpected non-tree root (lone)' '
67 test_must_fail git rev-list --objects $broken_commit
68 '
69
70 -test_expect_failure 'traverse unexpected non-tree root (seen)' '
71 - test_must_fail git rev-list --objects $blob $broken_commit
70 +test_expect_success 'traverse unexpected non-tree root (seen)' '
71 + test_must_fail git rev-list --objects $blob $broken_commit \
72 + >output 2>&1 &&
73 + test_i18ngrep "not a tree" output
74 '
75
76 test_expect_success 'setup unexpected non-commit tag' '