working on win32 uwp! and libremidi update

include/libremidi/backends/dummy.hpp

@@ -23,20 +23,33 @@ class midi_in_dummy final
     , public error_handler
 {
 public:
-  explicit midi_in_dummy(const auto& configuration, const auto&)
+  explicit midi_in_dummy(const input_configuration& configuration, std::any)
   {
-    warning(configuration, "midi_in_dummy: This class provides no functionality.");
+    libremidi_handle_warning(configuration, "This class provides no functionality.");
+  }
+  explicit midi_in_dummy(const ump_input_configuration& configuration, std::any)
+  {
+    libremidi_handle_warning(configuration, "This class provides no functionality.");
   }
 
   libremidi::API get_current_api() const noexcept override { return libremidi::API::DUMMY; }
-  bool open_port(const input_port& /*pt*/, std::string_view /*local_port_name*/) override
+  stdx::error open_port(const input_port& /*pt*/, std::string_view /*local_port_name*/) override
   {
-    return true;
+    return stdx::error{};
+  }
+  stdx::error open_virtual_port(std::string_view /*portName*/) override
+  {
+    return stdx::error{};
+  }
+  stdx::error close_port() override { return stdx::error{}; }
+  stdx::error set_client_name(std::string_view /*clientName*/) override
+  {
+    return stdx::error{};
+  }
+  stdx::error set_port_name(std::string_view /*portName*/) override
+  {
+    return stdx::error{};
   }
-  bool open_virtual_port(std::string_view /*portName*/) override { return true; }
-  void close_port() override { }
-  void set_client_name(std::string_view /*clientName*/) override { }
-  void set_port_name(std::string_view /*portName*/) override { }
   timestamp absolute_timestamp() const noexcept override { return 0; }
 };
 
@@ -45,22 +58,34 @@ class midi_out_dummy final
     , public error_handler
 {
 public:
-  explicit midi_out_dummy(const auto& configuration, const auto&)
+  explicit midi_out_dummy(const output_configuration& configuration, std::any)
   {
-    warning(configuration, "midi_out_dummy: This class provides no functionality.");
+    libremidi_handle_warning(configuration, "This class provides no functionality.");
   }
 
   libremidi::API get_current_api() const noexcept override { return libremidi::API::DUMMY; }
-  bool open_port(const output_port& /*pt*/, std::string_view /*local_port_name*/) override
+  stdx::error open_port(const output_port& /*pt*/, std::string_view /*local_port_name*/) override
   {
-    return true;
+    return stdx::error{};
+  }
+  stdx::error open_virtual_port(std::string_view /*portName*/) override
+  {
+    return stdx::error{};
   }
-  bool open_virtual_port(std::string_view /*portName*/) override { return true; }
 
-  void close_port() override { }
-  void set_client_name(std::string_view /*clientName*/) override { }
-  void set_port_name(std::string_view /*portName*/) override { }
-  void send_message(const unsigned char* /*message*/, size_t /*size*/) override { }
+  stdx::error close_port() override { return stdx::error{}; }
+  stdx::error set_client_name(std::string_view /*clientName*/) override
+  {
+    return stdx::error{};
+  }
+  stdx::error set_port_name(std::string_view /*portName*/) override
+  {
+    return stdx::error{};
+  }
+  stdx::error send_message(const unsigned char* /*message*/, size_t /*size*/) override
+  {
+    return stdx::error{};
+  }
 };
 
 struct dummy_backend