Subject: [PATCH v2 02/10] merge: check config before loading commits

From: Derrick Stolee <[email-masked]>
Date: Mon, 9 Apr 2018 16:41:57 +0000

In anticipation of using generation numbers from the commit-graph,
we must ensure that all commits that exist in the commit-graph are
loaded from that file instead of from the object database. Since
the commit-graph file is only checked if core.commitGraph is true,
we must check the default config before we load any commits.

In the merge builtin, the config was checked after loading the HEAD
commit. This was due to the use of the global 'branch' when checking
merge-specific config settings.

Move the config load to be between the initialization of 'branch'
and the commit lookup. Also add a test to t5318-commit-graph.sh
that exercises this code path to prevent a regression.

Signed-off-by: Derrick Stolee <[email-masked]>
---
 builtin/merge.c         | 5 +++--
 t/t5318-commit-graph.sh | 9 +++++++++
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/builtin/merge.c b/builtin/merge.c
index ee050a47f3..20897f8223 100644
--- a/builtin/merge.c
+++ b/builtin/merge.c
@@ -1183,13 +1183,14 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 	branch = branch_to_free = resolve_refdup("HEAD", 0, &head_oid, NULL);
 	if (branch)
 		skip_prefix(branch, "refs/heads/", &branch);
+	init_diff_ui_defaults();
+	git_config(git_merge_config, NULL);
+
 	if (!branch || is_null_oid(&head_oid))
 		head_commit = NULL;
 	else
 		head_commit = lookup_commit_or_die(&head_oid, "HEAD");
 
-	init_diff_ui_defaults();
-	git_config(git_merge_config, NULL);
 
 	if (branch_mergeoptions)
 		parse_branch_merge_options(branch_mergeoptions);
diff --git a/t/t5318-commit-graph.sh b/t/t5318-commit-graph.sh
index a380419b65..77d85aefe7 100755
--- a/t/t5318-commit-graph.sh
+++ b/t/t5318-commit-graph.sh
@@ -221,4 +221,13 @@ test_expect_success 'write graph in bare repo' '
 graph_git_behavior 'bare repo with graph, commit 8 vs merge 1' bare commits/8 merge/1
 graph_git_behavior 'bare repo with graph, commit 8 vs merge 2' bare commits/8 merge/2
 
+test_expect_success 'perform fast-forward merge in full repo' '
+	cd "$TRASH_DIRECTORY/full" &&
+	git checkout -b merge-5-to-8 commits/5 &&
+	git merge commits/8 &&
+	git show-ref -s merge-5-to-8 >output &&
+	git show-ref -s commits/8 >expect &&
+	test_cmp expect output
+'
+
 test_done
-- 
2.17.0