Improve error with incorrect order for command

src/driver/argument_parser.hpp

@@ -377,6 +377,14 @@ struct argument_parser
         };
     }
 
+    template<class T>
+    void set_exe_name_to(T& x)
+    {
+        actions.push_back([&](auto& self) {
+            x = self.exe_name;
+        });
+    }
+
     bool
     run_action(const argument& arg, const std::string& flag, const std::vector<std::string>& inputs)
     {
@@ -441,6 +449,8 @@ struct argument_parser
                 }
             }
         }
+        for(auto&& action:actions)
+            action(*this);
         return false;
     }
 
@@ -484,6 +494,7 @@ struct argument_parser
     private:
     std::list<argument> arguments;
     std::string exe_name = "";
+    std::vector<std::function<void(argument_parser&)>> actions;
 };
 
 } // namespace MIGRAPHX_INLINE_NS

src/driver/main.cpp

@@ -570,7 +570,7 @@ struct main_command
     {
         std::string version_str = "MIGraphX Version: " + std::to_string(MIGRAPHX_VERSION_MAJOR) +
                                   "." + std::to_string(MIGRAPHX_VERSION_MINOR);
-        ap(unused, {}, ap.metavar("<command>"), ap.set_value(true));
+        ap(wrong_commands, {}, ap.metavar("<command>"), ap.append());
         ap(nullptr, {"-h", "--help"}, ap.help("Show help"), ap.show_help(get_command_help()));
         ap(nullptr,
            {"-v", "--version"},
@@ -579,14 +579,32 @@ struct main_command
 
         // Trim command off of exe name
         ap.set_exe_name(ap.get_exe_name().substr(0, ap.get_exe_name().size() - 5));
+        ap.set_exe_name_to(exe_name);
     }
 
-    bool unused = false;
+    std::vector<std::string> wrong_commands{};
+    std::string exe_name = "<exe>";
 
     void run()
     {
         std::cout << color::fg_red << color::bold << "error: " << color::reset;
-        std::cout << get_command_help("missing command:") << std::endl;
+        auto it = std::find_if(wrong_commands.begin(), wrong_commands.end(), [](const auto& c) {
+            return get_commands().count(c) > 0;
+        });
+        if (it == wrong_commands.end())
+        {
+            std::cout << "'" << color::fg_yellow << wrong_commands.front() << color::reset << "' is not a valid command." << std::endl;
+            std::cout << get_command_help("Available commands:") << std::endl;
+        }
+        else
+        {
+            std::cout << "command '" << color::fg_yellow << *it << color::reset << "' must be first argument" << std::endl;
+            std::cout << std::endl;
+
+            std::cout << color::fg_yellow << "USAGE:" << color::reset << std::endl;
+            std::cout << "    " << exe_name << " " << *it << " <options>" << std::endl;
+        }
+        std::cout << std::endl;
     }
 };