Merge branch 'nm/maint-conflicted-submodule-entries' into maint

* nm/maint-conflicted-submodule-entries:
  submodule: process conflicting submodules only once

Documentation/git-submodule.txt

@@ -101,9 +101,10 @@ status::
 	currently checked out commit for each submodule, along with the
 	submodule path and the output of 'git describe' for the
 	SHA-1. Each SHA-1 will be prefixed with `-` if the submodule is not
-	initialized and `+` if the currently checked out submodule commit
+	initialized, `+` if the currently checked out submodule commit
 	does not match the SHA-1 found in the index of the containing
-	repository. This command is the default command for 'git submodule'.
+	repository and `U` if the submodule has merge conflicts.
+	This command is the default command for 'git submodule'.
 +
 If '--recursive' is specified, this command will recurse into nested
 submodules, and show their status as well.

git-submodule.sh

@@ -72,7 +72,24 @@ resolve_relative_url ()
 #
 module_list()
 {
-	git ls-files --error-unmatch --stage -- "$@" | sane_grep '^160000 '
+	git ls-files --error-unmatch --stage -- "$@" |
+	perl -e '
+	my %unmerged = ();
+	my ($null_sha1) = ("0" x 40);
+	while (<STDIN>) {
+		chomp;
+		my ($mode, $sha1, $stage, $path) =
+			/^([0-7]+) ([0-9a-f]{40}) ([0-3])\t(.*)$/;
+		next unless $mode eq "160000";
+		if ($stage ne "0") {
+			if (!$unmerged{$path}++) {
+				print "$mode $null_sha1 U\t$path\n";
+			}
+			next;
+		}
+		print "$_\n";
+	}
+	'
 }
 
 #
@@ -427,6 +444,11 @@ cmd_update()
 	module_list "$@" |
 	while read mode sha1 stage path
 	do
+		if test "$stage" = U
+		then
+			echo >&2 "Skipping unmerged submodule $path"
+			continue
+		fi
 		name=$(module_name "$path") || exit
 		url=$(git config submodule."$name".url)
 		update_module=$(git config submodule."$name".update)
@@ -770,6 +792,11 @@ cmd_status()
 		name=$(module_name "$path") || exit
 		url=$(git config submodule."$name".url)
 		displaypath="$prefix$path"
+		if test "$stage" = U
+		then
+			say "U$sha1 $displaypath"
+			continue
+		fi
 		if test -z "$url" || ! test -d "$path"/.git -o -f "$path"/.git
 		then
 			say "-$sha1 $displaypath"

t/t7405-submodule-merge.sh

@@ -56,11 +56,11 @@ test_expect_success setup '
 
 # History setup
 #
-#      b
-#    /   \
-#   a     d
-#    \   /
-#      c
+#             b
+#           /   \
+#  init -- a     d
+#    \      \   /
+#     g       c
 #
 # a in the main repository records to sub-a in the submodule and
 # analogous b and c. d should be automatically found by merging c into
@@ -76,6 +76,8 @@ test_expect_success 'setup for merge search' '
 	 git add file-a &&
 	 git commit -m "sub-a" &&
 	 git branch sub-a) &&
+	git commit --allow-empty -m init &&
+	git branch init &&
 	git add sub &&
 	git commit -m "a" &&
 	git branch a &&
@@ -101,7 +103,13 @@ test_expect_success 'setup for merge search' '
 	 git checkout -b sub-d sub-b &&
 	 git merge sub-c) &&
 	git commit -a -m "d" &&
-	git branch test b)
+	git branch test b &&
+
+	git checkout -b g init &&
+	(cd sub &&
+	 git checkout -b sub-g sub-c) &&
+	git add sub &&
+	git commit -a -m "g")
 '
 
 test_expect_success 'merge with one side as a fast-forward of the other' '
@@ -176,6 +184,44 @@ test_expect_success 'merging should fail for changes that are backwards' '
 	test_must_fail git merge f)
 '
 
+
+# Check that the conflicting submodule is detected when it is
+# in the common ancestor. status should be 'U00...00"
+test_expect_success 'git submodule status should display the merge conflict properly with merge base' '
+       (cd merge-search &&
+       cat >.gitmodules <<EOF &&
+[submodule "sub"]
+       path = sub
+       url = $TRASH_DIRECTORY/sub
+EOF
+       cat >expect <<EOF &&
+U0000000000000000000000000000000000000000 sub
+EOF
+       git submodule status > actual &&
+       test_cmp expect actual &&
+	git reset --hard)
+'
+
+# Check that the conflicting submodule is detected when it is
+# not in the common ancestor. status should be 'U00...00"
+test_expect_success 'git submodule status should display the merge conflict properly without merge-base' '
+       (cd merge-search &&
+	git checkout -b test-no-merge-base g &&
+	test_must_fail git merge b &&
+       cat >.gitmodules <<EOF &&
+[submodule "sub"]
+       path = sub
+       url = $TRASH_DIRECTORY/sub
+EOF
+       cat >expect <<EOF &&
+U0000000000000000000000000000000000000000 sub
+EOF
+       git submodule status > actual &&
+       test_cmp expect actual &&
+       git reset --hard)
+'
+
+
 test_expect_success 'merging with a modify/modify conflict between merge bases' '
 	git reset --hard HEAD &&
 	git checkout -b test2 c &&