Fix program path in help

pi2-demo/meson.build

@@ -13,6 +13,6 @@ pi2_demo_src = files(
 boost_po_dep = dependency('boost', modules : ['program_options'])
 executable('pi2-demo', pi2_demo_src,
     include_directories: pi2_demo_inc,
-    dependencies: [pi2_view_dep, boost_po_dep],
+    dependencies: [pi2_view_dep, boost_po_dep, microsoft_gsl_dep],
     install: true
 )

pi2-demo/src/main.cpp

@@ -2,6 +2,8 @@
 #include <boost/program_options.hpp>
 #include <chrono>
 #include <fstream>
+#include <gsl/span>
+#include <gsl/string_span>
 #include <iostream>
 #include <ratio>
 #include <string>
@@ -9,6 +11,8 @@
 namespace po = boost::program_options;
 
 int main(int argc, char *argv[]) {
+  auto args = gsl::make_span(argv, argc);
+
   try {
     std::string durationString;
     double timescale;
@@ -45,10 +49,11 @@ int main(int argc, char *argv[]) {
     po::notify(variablesMap);
 
     if (variablesMap.count("help") > 0) {
-      std::cout
-          << "Usage: ./pi2-demo/pi2-demo [OPTION]... [FILE]\n"
-             "Parses and simulates FILE according to the PI-2 of the RWTH.\n\n"
-          << visibleOptions << std::endl;
+      std::cout << "Usage: " + std::string(args.at(0)) +
+                       " [OPTION]... [FILE]\n"
+                       "Parses and simulates FILE according to the PI-2 of the "
+                       "RWTH.\n\n"
+                << visibleOptions << std::endl;
       return 1;
     }