[PATCH v3 2/2] builtin/am: allow disabling conflict advice

["Philippe Blain via GitGitGadget" <gitgitgadget@gmail.com>]

From: Philippe Blain <levraiphilippeblain@gmail.com>

When 'git am' or 'git rebase --apply' encounter a conflict, they show a
message instructing the user how to continue the operation. This message
can't be disabled.

Use ADVICE_MERGE_CONFLICT introduced in the previous commit to allow
disabling it. Update the tests accordingly, as the advice output is now
on stderr instead of stdout. In t4150, redirect stdout to 'out' and
stderr to 'err', since this is less confusing. In t4254, as we are
testing a specific failure mode of 'git am', simply disable the advice.
Note that we are not testing that this advice is shown in 'git rebase'
for the apply backend since 2ac0d6273f (rebase: change the default
backend from "am" to "merge", 2020-02-15).

Helped-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Helped-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Philippe Blain <levraiphilippeblain@gmail.com>
---
 builtin/am.c          | 14 +++++++++-----
 t/t4150-am.sh         |  8 ++++----
 t/t4254-am-corrupt.sh |  2 +-
 3 files changed, 14 insertions(+), 10 deletions(-)

diff --git a/builtin/am.c b/builtin/am.c
index d1990d7edcb..d87847205c7 100644
--- a/builtin/am.c
+++ b/builtin/am.c
@@ -1150,19 +1150,23 @@ static const char *msgnum(const struct am_state *state)
 static void NORETURN die_user_resolve(const struct am_state *state)
 {
 	if (state->resolvemsg) {
-		printf_ln("%s", state->resolvemsg);
+		advise_if_enabled(ADVICE_MERGE_CONFLICT, "%s", state->resolvemsg);
 	} else {
 		const char *cmdline = state->interactive ? "git am -i" : "git am";
+		struct strbuf sb = STRBUF_INIT;
 
-		printf_ln(_("When you have resolved this problem, run \"%s --continue\"."), cmdline);
-		printf_ln(_("If you prefer to skip this patch, run \"%s --skip\" instead."), cmdline);
+		strbuf_addf(&sb, _("When you have resolved this problem, run \"%s --continue\".\n"), cmdline);
+		strbuf_addf(&sb, _("If you prefer to skip this patch, run \"%s --skip\" instead.\n"), cmdline);
 
 		if (advice_enabled(ADVICE_AM_WORK_DIR) &&
 		    is_empty_or_missing_file(am_path(state, "patch")) &&
 		    !repo_index_has_changes(the_repository, NULL, NULL))
-			printf_ln(_("To record the empty patch as an empty commit, run \"%s --allow-empty\"."), cmdline);
+			strbuf_addf(&sb, _("To record the empty patch as an empty commit, run \"%s --allow-empty\".\n"), cmdline);
 
-		printf_ln(_("To restore the original branch and stop patching, run \"%s --abort\"."), cmdline);
+		strbuf_addf(&sb, _("To restore the original branch and stop patching, run \"%s --abort\"."), cmdline);
+
+		advise_if_enabled(ADVICE_MERGE_CONFLICT, "%s", sb.buf);
+		strbuf_release(&sb);
 	}
 
 	exit(128);
diff --git a/t/t4150-am.sh b/t/t4150-am.sh
index 3b125762694..5e2b6c80eae 100755
--- a/t/t4150-am.sh
+++ b/t/t4150-am.sh
@@ -1224,8 +1224,8 @@ test_expect_success 'record as an empty commit when meeting e-mail message that
 
 test_expect_success 'skip an empty patch in the middle of an am session' '
 	git checkout empty-commit^ &&
-	test_must_fail git am empty-commit.patch >err &&
-	grep "Patch is empty." err &&
+	test_must_fail git am empty-commit.patch >out 2>err &&
+	grep "Patch is empty." out &&
 	grep "To record the empty patch as an empty commit, run \"git am --allow-empty\"." err &&
 	git am --skip &&
 	test_path_is_missing .git/rebase-apply &&
@@ -1236,8 +1236,8 @@ test_expect_success 'skip an empty patch in the middle of an am session' '
 
 test_expect_success 'record an empty patch as an empty commit in the middle of an am session' '
 	git checkout empty-commit^ &&
-	test_must_fail git am empty-commit.patch >err &&
-	grep "Patch is empty." err &&
+	test_must_fail git am empty-commit.patch >out 2>err &&
+	grep "Patch is empty." out &&
 	grep "To record the empty patch as an empty commit, run \"git am --allow-empty\"." err &&
 	git am --allow-empty >output &&
 	grep "No changes - recorded it as an empty commit." output &&
diff --git a/t/t4254-am-corrupt.sh b/t/t4254-am-corrupt.sh
index 45f1d4f95e5..661feb60709 100755
--- a/t/t4254-am-corrupt.sh
+++ b/t/t4254-am-corrupt.sh
@@ -59,7 +59,7 @@ test_expect_success setup '
 # Also, it had the unwanted side-effect of deleting f.
 test_expect_success 'try to apply corrupted patch' '
 	test_when_finished "git am --abort" &&
-	test_must_fail git -c advice.amWorkDir=false am bad-patch.diff 2>actual &&
+	test_must_fail git -c advice.amWorkDir=false -c advice.mergeConflict=false am bad-patch.diff 2>actual &&
 	echo "error: git diff header lacks filename information (line 4)" >expected &&
 	test_path_is_file f &&
 	test_cmp expected actual
-- 
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