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[PATCH v2] submodule merge: update conflict error message

From
Calvin Wan <calvinwan@google.com>
Date
Jun 10, 2022, 23:11 UTC
Message-ID
<20220610231152.2594428-1-calvinwan@google.com>
In-Reply-To
<20220606235449.2890858-1-calvinwan@google.com>

When attempting to do a non-fast-forward merge in a project with conflicts in the submodules, the merge fails and git prints the following error:

Failed to merge submodule <submodules> CONFLICT (submodule):Merge conflict in <submodule> Automatic merge failed; fix conflicts and then commit the result.

Git is left in a conflicted state, which requires the user to:
 1. merge submodules
 2. add submodules changes to the superproject
 3. merge superproject
These steps are non-obvious for newer submodule users to figure out
based on the error message and neither `git submodule status` nor `git
status` provide any useful pointers.

Update error message to the following when attempting to do a non-fast-forward merge in a project with conflicts in the submodules. The error message is based off of what would happen when `merge --recurse-submodules` is eventually supported

Failed to merge submodule <submodule>
CONFLICT (submodule): Merge conflict in <submodule>
Automatic merge failed; recursive merging with submodules is currently
not supported. To manually complete the merge:
 - go to submodule (<submodule>), and merge commit <commit>
 - come back to superproject, and `git add <submodule>` to record the above merge 
 - resolve any other conflicts in the superproject
 - commit the resulting index in the superproject
Changes since v1:
 - Removed advice to abort merge
 - Error message updated to contain more commit/submodule information
Signed-off-by: Calvin Wan <calvinwan@google.com>
---
 builtin/merge.c            | 23 ++++++++++++++++++++++-
 merge-ort.c                |  7 ++++++-
 merge-recursive.c          |  7 ++++++-
 merge-recursive.h          |  4 ++++
 t/t6437-submodule-merge.sh |  5 ++++-
 5 files changed, 42 insertions(+), 4 deletions(-)
diff --git a/builtin/merge.c b/builtin/merge.c
index f178f5a3ee..7e2deea7fb 100644
--- a/builtin/merge.c
+++ b/builtin/merge.c
@@ -88,6 +88,8 @@ static const char *sign_commit;
 static int autostash;
 static int no_verify;
 static char *into_name;
+static struct oid_array conflicted_submodule_oids = OID_ARRAY_INIT;
+static struct string_list conflicted_submodule_paths = STRING_LIST_INIT_DUP;
 
 static struct strategy all_strategy[] = {
 	{ "recursive",  NO_TRIVIAL },
@@ -734,6 +736,8 @@ static int try_merge_strategy(const char *strategy, struct commit_list *common,
 		}
 
 		init_merge_options(&o, the_repository);
+		o.conflicted_submodule_oids = &conflicted_submodule_oids;
+		o.conflicted_submodule_paths = &conflicted_submodule_paths;
 		if (!strcmp(strategy, "subtree"))
 			o.subtree_shift = "";
 
@@ -973,8 +977,25 @@ static int suggest_conflicts(void)
 	strbuf_release(&msgbuf);
 	fclose(fp);
 	repo_rerere(the_repository, allow_rerere_auto);
-	printf(_("Automatic merge failed; "
+	if (conflicted_submodule_oids.nr > 0) {
+		int i;
+		printf(_("Automatic merge failed; recursive merging with submodules is currently\n"
+			"not supported. To manually complete the merge:\n"));
+		for (i = 0; i < conflicted_submodule_oids.nr; i++) {
+			printf(_(" - go to submodule (%s), and merge commit %s\n"),
+				conflicted_submodule_paths.items[i].string,
+				oid_to_hex(&conflicted_submodule_oids.oid[i]));
+		}
+		printf(_(" - come back to superproject, and `git add"));
+		for (i = 0; i < conflicted_submodule_paths.nr; i++)
+			printf(_(" %s"), conflicted_submodule_paths.items[i].string);
+		printf(_("` to record the above merge \n"
+		" - resolve any other conflicts in the superproject\n"
+		" - commit the resulting index in the superproject\n"));
+	} else {
+		printf(_("Automatic merge failed; "
 			"fix conflicts and then commit the result.\n"));
+	}
 	return 1;
 }
 
diff --git a/merge-ort.c b/merge-ort.c
index 0d3f42592f..c86ee11614 100644
--- a/merge-ort.c
+++ b/merge-ort.c
@@ -3866,8 +3866,13 @@ static void process_entry(struct merge_options *opt,
 			const char *reason = _("content");
 			if (ci->filemask == 6)
 				reason = _("add/add");
-			if (S_ISGITLINK(merged_file.mode))
+			if (S_ISGITLINK(merged_file.mode)) {
 				reason = _("submodule");
+				if (opt->conflicted_submodule_oids && opt->conflicted_submodule_paths) {
+					oid_array_append(opt->conflicted_submodule_oids, &merged_file.oid);
+					string_list_append(opt->conflicted_submodule_paths, path);
+				}
+			}
 			path_msg(opt, path, 0,
 				 _("CONFLICT (%s): Merge conflict in %s"),
 				 reason, path);
diff --git a/merge-recursive.c b/merge-recursive.c
index fd1bbde061..ff7cdbefe9 100644
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -3149,8 +3149,13 @@ static int handle_content_merge(struct merge_file_info *mfi,
 	}
 
 	if (!mfi->clean) {
-		if (S_ISGITLINK(mfi->blob.mode))
+		if (S_ISGITLINK(mfi->blob.mode)) {
 			reason = _("submodule");
+			if (opt->conflicted_submodule_oids && opt->conflicted_submodule_paths) {
+				oid_array_append(opt->conflicted_submodule_oids, &mfi->blob.oid);
+				string_list_append(opt->conflicted_submodule_paths, path);
+			}
+		}
 		output(opt, 1, _("CONFLICT (%s): Merge conflict in %s"),
 				reason, path);
 		if (ci && !df_conflict_remains)
diff --git a/merge-recursive.h b/merge-recursive.h
index b88000e3c2..5d267e7a43 100644
--- a/merge-recursive.h
+++ b/merge-recursive.h
@@ -51,6 +51,10 @@ struct merge_options {
 
 	/* internal fields used by the implementation */
 	struct merge_options_internal *priv;
+
+	/* fields that hold submodule conflict information */
+	struct oid_array *conflicted_submodule_oids;
+	struct string_list *conflicted_submodule_paths;
 };
 
 void init_merge_options(struct merge_options *opt, struct repository *repo);
diff --git a/t/t6437-submodule-merge.sh b/t/t6437-submodule-merge.sh
index 178413c22f..5b384dedc1 100755
--- a/t/t6437-submodule-merge.sh
+++ b/t/t6437-submodule-merge.sh
@@ -141,6 +141,7 @@ test_expect_success 'merging should conflict for non fast-forward' '
 		test_must_fail git merge c 2> actual
 	  fi &&
 	 grep $(cat expect) actual > /dev/null &&
+	 test_i18ngrep "go to submodule (sub), and merge commit $(git -C sub rev-parse sub-b)" actual &&
 	 git reset --hard)
 '
 
@@ -167,6 +168,7 @@ test_expect_success 'merging should fail for ambiguous common parent' '
 	 fi &&
 	grep $(cat expect1) actual > /dev/null &&
 	grep $(cat expect2) actual > /dev/null &&
+	test_i18ngrep "go to submodule (sub), and merge commit $(git -C sub rev-parse sub-b)" actual &&
 	git reset --hard)
 '
 
@@ -205,7 +207,8 @@ test_expect_success 'merging should fail for changes that are backwards' '
 	git commit -a -m "f" &&
 
 	git checkout -b test-backward e &&
-	test_must_fail git merge f)
+	test_must_fail git merge f >actual &&
+	test_i18ngrep "go to submodule (sub), and merge commit $(git -C sub rev-parse sub-a)" actual)
 '
 
 

-- 
2.36.1.476.g0c4daa206d-goog
Previous: Junio C HamanoNext: Elijah Newren
Message 7 of 60 in “submodule merge: update conflict error message”
  1. submodule merge: update conflict error messageCalvin Wan, Jun 6, 2022
  2. Junio C HamanoJun 7, 2022
  3. Calvin WanJun 8, 2022
  4. Glen ChooJun 8, 2022
  5. Calvin WanJun 8, 2022
  6. Junio C HamanoJun 8, 2022
  7. submodule merge: update conflict error messageCalvin Wan, Jun 10, 2022
  8. Elijah NewrenJun 11, 2022
  9. Philippe BlainJun 11, 2022
  10. Elijah NewrenJun 12, 2022
  11. Calvin WanJun 13, 2022
  12. Junio C HamanoJun 12, 2022
  13. Calvin WanJun 13, 2022
  14. submodule merge: update conflict error messageCalvin Wan, Jun 29, 2022
  15. Elijah NewrenJun 30, 2022
  16. Calvin WanJun 30, 2022
  17. Elijah NewrenJul 1, 2022
  18. Glen ChooJun 30, 2022
  19. Glen ChooJun 30, 2022
  20. Calvin WanJun 30, 2022
  21. submodule merge: update conflict error messageCalvin Wan, Jul 12, 2022
  22. Junio C HamanoJul 13, 2022
  23. Elijah NewrenJul 17, 2022
  24. Johannes SchindelinJul 15, 2022
  25. Junio C HamanoJul 16, 2022
  26. Elijah NewrenJul 17, 2022
  27. Calvin WanJul 18, 2022
  28. submodule merge: update conflict error messageCalvin Wan, Jul 18, 2022
  29. Junio C HamanoJul 19, 2022
  30. Calvin WanJul 19, 2022
  31. Junio C HamanoJul 19, 2022
  32. Junio C HamanoJul 19, 2022
  33. Calvin WanJul 19, 2022
  34. Junio C HamanoJul 19, 2022
  35. Ævar Arnfjörð BjarmasonJul 25, 2022
  36. Ævar Arnfjörð BjarmasonJul 25, 2022
  37. Calvin WanJul 25, 2022
  38. Ævar Arnfjörð BjarmasonJul 25, 2022
  39. Calvin WanJul 25, 2022
  40. submodule merge: update conflict error messageCalvin Wan, Jul 26, 2022
  41. Elijah NewrenJul 27, 2022
  42. Calvin WanJul 27, 2022
  43. Elijah NewrenJul 28, 2022
  44. Calvin WanJul 28, 2022
  45. Ævar Arnfjörð BjarmasonJul 27, 2022
  46. submodule merge: update conflict error messageCalvin Wan, Jul 28, 2022
  47. Ævar Arnfjörð BjarmasonJul 28, 2022
  48. Elijah NewrenJul 29, 2022
  49. Calvin WanAug 1, 2022
  50. Ævar Arnfjörð BjarmasonAug 1, 2022
  51. Junio C HamanoAug 2, 2022
  52. Calvin WanAug 2, 2022
  53. Junio C HamanoAug 2, 2022
  54. Calvin WanAug 2, 2022
  55. Junio C HamanoAug 2, 2022
  56. submodule merge: update conflict error messageCalvin Wan, Aug 4, 2022
  57. Junio C HamanoAug 16, 2022
  58. Junio C HamanoAug 16, 2022
  59. Calvin WanAug 16, 2022
  60. Junio C HamanoAug 16, 2022

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