From 1bb1846f61266e8ee3a924b7e57356ac49044d77 Mon Sep 17 00:00:00 2001
From: Nicole Lemaster Slattengren <nlslatt@sandia.gov>
Date: Mon, 20 Sep 2021 13:02:53 -0700
Subject: [PATCH] #1359: config: add cli argument for lb arg help

---
 src/vt/configs/arguments/app_config.h | 2 ++
 src/vt/configs/arguments/args.cc      | 8 +++++++-
 src/vt/runtime/runtime.cc             | 8 ++++++++
 3 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/src/vt/configs/arguments/app_config.h b/src/vt/configs/arguments/app_config.h
index 31323502b3..109ef7a36f 100644
--- a/src/vt/configs/arguments/app_config.h
+++ b/src/vt/configs/arguments/app_config.h
@@ -145,6 +145,7 @@ struct AppConfig {
   std::string vt_lb_stats_file    = "stats.%p.json";
   std::string vt_lb_stats_dir_in  = "vt_lb_stats_in";
   std::string vt_lb_stats_file_in = "stats.%p.json";
+  bool vt_help_lb_args        = false;
 
   bool vt_no_detect_hang       = false;
   bool vt_print_no_progress    = true;
@@ -308,6 +309,7 @@ struct AppConfig {
       | vt_lb_stats_file
       | vt_lb_stats_dir_in
       | vt_lb_stats_file_in
+      | vt_help_lb_args
 
       | vt_no_detect_hang
       | vt_print_no_progress
diff --git a/src/vt/configs/arguments/args.cc b/src/vt/configs/arguments/args.cc
index 07ef21e4ef..a47865ad16 100644
--- a/src/vt/configs/arguments/args.cc
+++ b/src/vt/configs/arguments/args.cc
@@ -343,7 +343,7 @@ void ArgConfig::addLbArgs(CLI::App& app) {
    * Flags for enabling load balancing and configuring it
    */
   auto lb            = "Enable load balancing";
-  auto lb_args       = "Arguments pass to LB: \"x=0 y=1 test=2\"";
+  auto lb_args       = "Arguments pass to LB: \"x=0 y=1\"; try --vt_help_lb_args";
   auto lb_quiet      = "Silence load balancing output";
   auto lb_file_name  = "LB specification file to read";
   auto lb_show_spec  = "Show LB specification during startup";
@@ -393,6 +393,12 @@ void ArgConfig::addLbArgs(CLI::App& app) {
   xx->group(debugLB);
   xy->group(debugLB);
   xz->group(debugLB);
+
+  // help options deliberately omitted from the debugLB group above so that
+  // they appear grouped with --vt_help when --vt_help is used
+  auto help_lb_args  = "Print help for --vt_lb_args";
+  auto h1 = app.add_flag("--vt_help_lb_args", config_.vt_help_lb_args, help_lb_args);
+  (void) h1;
 }
 
 void ArgConfig::addDiagnosticArgs(CLI::App& app) {
diff --git a/src/vt/runtime/runtime.cc b/src/vt/runtime/runtime.cc
index 0d39597ed5..c7506985de 100644
--- a/src/vt/runtime/runtime.cc
+++ b/src/vt/runtime/runtime.cc
@@ -156,6 +156,14 @@ Runtime::Runtime(
     arg_config_->parse(/*out*/ argc, /*out*/ argv);
   int exit_code = std::get<0>(result);
 
+  if (getAppConfig()->vt_help_lb_args) {
+    // Help requested
+    vrt::collection::balance::LBManager::printLBArgsHelp(getAppConfig()->vt_lb_name);
+     if (exit_code == -1) {
+       exit_code = 0;
+     }
+  }
+
   if (exit_code not_eq -1) {
     // Help requested or invalid argument(s).
     MPI_Comm comm = initial_communicator_;