completion: teach submodule subcommands to complete options

Each submodule subcommand has specific long-options. Therefore, teach
bash completion to support option completion based on the current
subcommand. All long-options that are mentioned in the man-page synopsis
are added.

Signed-off-by: Cornelius Weig <cornelius.weig@tngtech.com>
Reviewed-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: Cornelius Weig

contrib/completion/git-completion.bash

@@ -2556,17 +2556,45 @@ _git_submodule ()
 	__git_has_doubledash && return
 
 	local subcommands="add status init deinit update summary foreach sync"
-	if [ -z "$(__git_find_on_cmdline "$subcommands")" ]; then
+	local subcommand="$(__git_find_on_cmdline "$subcommands")"
+	if [ -z "$subcommand" ]; then
 		case "$cur" in
 		--*)
-			__gitcomp "--quiet --cached"
+			__gitcomp "--quiet"
 			;;
 		*)
 			__gitcomp "$subcommands"
 			;;
 		esac
 		return
 	fi
+
+	case "$subcommand,$cur" in
+	add,--*)
+		__gitcomp "--branch --force --name --reference --depth"
+		;;
+	status,--*)
+		__gitcomp "--cached --recursive"
+		;;
+	deinit,--*)
+		__gitcomp "--force --all"
+		;;
+	update,--*)
+		__gitcomp "
+			--init --remote --no-fetch
+			--recommend-shallow --no-recommend-shallow
+			--force --rebase --merge --reference --depth --recursive --jobs
+		"
+		;;
+	summary,--*)
+		__gitcomp "--cached --files --summary-limit"
+		;;
+	foreach,--*|sync,--*)
+		__gitcomp "--recursive"
+		;;
+	*)
+		;;
+	esac
 }
 
 _git_svn ()