submodule: add --progress option to add command

The '--progress' was introduced in 72c5f88311 (clone: pass --progress
decision to recursive submodules, 2016-09-22) to fix the progress reporting
of the clone command. Also add the progress option to the 'submodule add'
command. The update command already supports the progress flag, but it
is not documented.

Signed-off-by: Casey Fitzpatrick <kcghost@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-submodule.txt

@@ -239,6 +239,13 @@ OPTIONS
 --quiet::
 	Only print error messages.
 
+--progress::
+	This option is only valid for add and update commands.
+	Progress status is reported on the standard error stream
+	by default when it is attached to a terminal, unless -q
+	is specified. This flag forces progress status even if the
+	standard error stream is not directed to a terminal.
+
 --all::
 	This option is only valid for the deinit command. Unregister all
 	submodules in the working tree.

git-submodule.sh

@@ -117,6 +117,9 @@ cmd_add()
 		-q|--quiet)
 			GIT_QUIET=1
 			;;
+		--progress)
+			progress=1
+			;;
 		--reference)
 			case "$2" in '') usage ;; esac
 			reference_path=$2
@@ -255,7 +258,7 @@ or you are unsure what this means choose another name with the '--name' option."
 				eval_gettextln "Reactivating local git directory for submodule '\$sm_name'."
 			fi
 		fi
-		git submodule--helper clone ${GIT_QUIET:+--quiet} --prefix "$wt_prefix" --path "$sm_path" --name "$sm_name" --url "$realrepo" ${reference:+"$reference"} ${depth:+"$depth"} || exit
+		git submodule--helper clone ${GIT_QUIET:+--quiet} ${progress:+"--progress"} --prefix "$wt_prefix" --path "$sm_path" --name "$sm_name" --url "$realrepo" ${reference:+"$reference"} ${depth:+"$depth"} || exit
 		(
 			sanitize_submodule_env
 			cd "$sm_path" &&

t/t7400-submodule-basic.sh

@@ -126,6 +126,22 @@ test_expect_success 'submodule add' '
 	test_cmp empty untracked
 '
 
+test_create_repo parent &&
+test_commit -C parent one
+
+test_expect_success 'redirected submodule add does not show progress' '
+	git -C addtest submodule add "file://$submodurl/parent" submod-redirected \
+		2>err &&
+	! grep % err &&
+	test_i18ngrep ! "Checking connectivity" err
+'
+
+test_expect_success 'redirected submodule add --progress does show progress' '
+	git -C addtest submodule add --progress "file://$submodurl/parent" \
+		submod-redirected-progress 2>err && \
+	grep % err
+'
+
 test_expect_success 'submodule add to .gitignored path fails' '
 	(
 		cd addtest-ignore &&