[PATCH v9 29.25/30] merge-recursive: improve output precision around skipping updates

[Elijah Newren <newren@gmail.com>]

When a merge results in contents that already existed in HEAD (because the
changes on a side branch were a subset of what was changed by HEAD), and
those contents were already at the right path, the working directory
updates can be skipped.  However, the relevant code would sometimes claim
the working directory update could be skipped despite the fact that the
contents were at the wrong path.  Make the output reflect the situation
more precisely, including an additional message that tests can check for
to make sure we are getting correct behavior.

Signed-off-by: Elijah Newren <newren@gmail.com>
---
 merge-recursive.c       | 11 ++++++-----
 t/t6022-merge-rename.sh |  2 +-
 2 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/merge-recursive.c b/merge-recursive.c
index 4a1ecdea03..05250939c7 100644
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -2761,21 +2761,22 @@ static int merge_content(struct merge_options *o,
 				       o->branch2, path2, &mfi))
 		return -1;
 
-	if (mfi.clean && !df_conflict_remains &&
-	    oid_eq(&mfi.oid, a_oid) && mfi.mode == a_mode) {
+	if (mfi.clean && oid_eq(&mfi.oid, a_oid) && mfi.mode == a_mode) {
 		int path_renamed_outside_HEAD;
-		output(o, 3, _("Skipped %s (merged same as existing)"), path);
 		/*
 		 * The content merge resulted in the same file contents we
 		 * already had.  We can return early if those file contents
 		 * are recorded at the correct path (which may not be true
-		 * if the merge involves a rename).
+		 * if the merge involves a rename or there's a D/F conflict).
 		 */
 		path_renamed_outside_HEAD = !path2 || !strcmp(path, path2);
-		if (!path_renamed_outside_HEAD) {
+		if (!df_conflict_remains && !path_renamed_outside_HEAD) {
+			output(o, 3, _("Skipped %s (merged same as existing)"), path);
 			add_cacheinfo(o, mfi.mode, &mfi.oid, path,
 				      0, (!o->call_depth), 0);
 			return mfi.clean;
+		} else {
+			output(o, 3, _("Had correct contents for %s, but not at right path"), path);
 		}
 	} else
 		output(o, 2, _("Auto-merging %s"), path);
diff --git a/t/t6022-merge-rename.sh b/t/t6022-merge-rename.sh
index 05ebba7afa..574088bfaf 100755
--- a/t/t6022-merge-rename.sh
+++ b/t/t6022-merge-rename.sh
@@ -245,7 +245,7 @@ test_expect_success 'merge of identical changes in a renamed file' '
 	GIT_MERGE_VERBOSITY=3 git merge change | test_i18ngrep "^Skipped B" &&
 	git reset --hard HEAD^ &&
 	git checkout change &&
-	GIT_MERGE_VERBOSITY=3 git merge change+rename | test_i18ngrep "^Skipped B"
+	GIT_MERGE_VERBOSITY=3 git merge change+rename | test_i18ngrep "^Had correct contents for B, but not at right path"
 '
 
 test_expect_success 'setup for rename + d/f conflicts' '
-- 
2.16.0.35.g6dd7ede834