[PATCH v3 4/9] merge-ort: capture and print ll-merge warnings in our preferred fashion

["Elijah Newren via GitGitGadget" <gitgitgadget@xxxxxxxxx>]

From: Elijah Newren <newren@xxxxxxxxx>

Instead of immediately printing ll-merge warnings to stderr, we save
them in our output strbuf.  Besides allowing us to move these warnings
to a special file for --remerge-diff, this has two other benefits for
regular merges done by merge-ort:

  * The deferral of messages ensures we can print all messages about
    any given path together (merge-recursive was known to sometimes
    intersperse messages about other paths, particularly when renames
    were involved).

  * The deferral of messages means we can avoid printing spurious
    conflict messages when we just end up aborting due to local user
    modifications in the way.  (In contrast to merge-recursive.c which
    prematurely checks for local modifications in the way via
    unpack_trees() and gets the check wrong both in terms of false
    positives and false negatives relative to renames, merge-ort does
    not perform the local modifications in the way check until the
    checkout() step after the full merge has been computed.)

Signed-off-by: Elijah Newren <newren@xxxxxxxxx>
---
 merge-ort.c                | 5 +++--
 t/t6404-recursive-merge.sh | 9 +++++++--
 t/t6406-merge-attr.sh      | 9 +++++++--
 3 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/merge-ort.c b/merge-ort.c
index c24da2ba3cb..a18f47e23c5 100644
--- a/merge-ort.c
+++ b/merge-ort.c
@@ -1788,8 +1788,9 @@ static int merge_3way(struct merge_options *opt,
 				&src1, name1, &src2, name2,
 				&opt->priv->attr_index, &ll_opts);
 	if (merge_status == LL_MERGE_BINARY_CONFLICT)
-		warning("Cannot merge binary files: %s (%s vs. %s)",
-			path, name1, name2);
+		path_msg(opt, path, 0,
+			 "warning: Cannot merge binary files: %s (%s vs. %s)",
+			 path, name1, name2);
 
 	free(base);
 	free(name1);
diff --git a/t/t6404-recursive-merge.sh b/t/t6404-recursive-merge.sh
index eaf48e941e2..b8735c6db4d 100755
--- a/t/t6404-recursive-merge.sh
+++ b/t/t6404-recursive-merge.sh
@@ -108,8 +108,13 @@ test_expect_success 'refuse to merge binary files' '
 	printf "\0\0" >binary-file &&
 	git add binary-file &&
 	git commit -m binary2 &&
-	test_must_fail git merge F >merge.out 2>merge.err &&
-	grep "Cannot merge binary files: binary-file (HEAD vs. F)" merge.err
+	if test "$GIT_TEST_MERGE_ALGORITHM" = ort
+	then
+		test_must_fail git merge F >merge_output
+	else
+		test_must_fail git merge F 2>merge_output
+	fi &&
+	grep "Cannot merge binary files: binary-file (HEAD vs. F)" merge_output
 '
 
 test_expect_success 'mark rename/delete as unmerged' '
diff --git a/t/t6406-merge-attr.sh b/t/t6406-merge-attr.sh
index 84946458371..c41584eb33e 100755
--- a/t/t6406-merge-attr.sh
+++ b/t/t6406-merge-attr.sh
@@ -221,8 +221,13 @@ test_expect_success 'binary files with union attribute' '
 	printf "two\0" >bin.txt &&
 	git commit -am two &&
 
-	test_must_fail git merge bin-main 2>stderr &&
-	grep -i "warning.*cannot merge.*HEAD vs. bin-main" stderr
+	if test "$GIT_TEST_MERGE_ALGORITHM" = ort
+	then
+		test_must_fail git merge bin-main >output
+	else
+		test_must_fail git merge bin-main 2>output
+	fi &&
+	grep -i "warning.*cannot merge.*HEAD vs. bin-main" output
 '
 
 test_done
-- 
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