A few minor tweaks to make compatible with build systems (#613)

Author: Scottj1s

cppwinrt/cmd_reader.h

@@ -515,7 +515,7 @@ namespace cppwinrt
         template<typename O, typename L>
         void extract_option(std::string_view arg, O const& options, L& last)
         {
-            if (arg[0] == '-')
+            if (arg[0] == '-' || arg[0] == '/')
             {
                 arg.remove_prefix(1);
                 last = find(options, arg);

cppwinrt/main.cpp

@@ -31,6 +31,7 @@ namespace cppwinrt
         { "base", 0, 0, {}, "Generate base.h unconditionally" },
         { "optimize", 0, 0, {}, "Generate component projection with unified construction support" },
         { "help", 0, option::no_max, {}, "Show detailed help with examples" },
+        { "?", 0, option::no_max, {}, {} },
         { "library", 0, 1, "<prefix>", "Specify library prefix (defaults to winrt)" },
         { "filter" }, // One or more prefixes to include in input (same as -include)
         { "license", 0, 0 }, // Generate license comment
@@ -252,7 +253,7 @@ Where <spec> is one or more of:
 
             reader args{ argc, argv, options };
 
-            if (!args || args.exists("help"))
+            if (!args || args.exists("help") || args.exists("?"))
             {
                 throw usage_exception{};
             }
@@ -366,7 +367,7 @@ Where <spec> is one or more of:
             result = 1;
         }
 
-        w.flush_to_console();
+        w.flush_to_console(result == 0);
         return result;
     }
 }

cppwinrt/text_writer.h

@@ -145,10 +145,10 @@ namespace cppwinrt
             std::swap(m_second, m_first);
         }
 
-        void flush_to_console() noexcept
+        void flush_to_console(bool to_stdout = true) noexcept
         {
-            printf("%.*s", static_cast<int>(m_first.size()), m_first.data());
-            printf("%.*s", static_cast<int>(m_second.size()), m_second.data());
+            fprintf(to_stdout ? stdout : stderr, "%.*s", static_cast<int>(m_first.size()), m_first.data());
+            fprintf(to_stdout ? stdout : stderr, "%.*s", static_cast<int>(m_second.size()), m_second.data());
             m_first.clear();
             m_second.clear();
         }