LibusbUtils: Create ErrorWrap

Source/Core/Core/LibusbUtils.cpp

@@ -23,7 +23,7 @@ public:
   Impl()
   {
     const int ret = libusb_init(&m_context);
-    ASSERT_MSG(IOS_USB, ret == LIBUSB_SUCCESS, "Failed to init libusb: {}", libusb_error_name(ret));
+    ASSERT_MSG(IOS_USB, ret == LIBUSB_SUCCESS, "Failed to init libusb: {}", ErrorWrap(ret));
     if (ret != LIBUSB_SUCCESS)
       return;
 
@@ -118,4 +118,22 @@ ConfigDescriptor MakeConfigDescriptor(libusb_device* device, u8 config_num)
 #endif
   return {nullptr, [](auto) {}};
 }
+
+const char* ErrorWrap::GetName() const
+{
+#if defined(__LIBUSB__)
+  return libusb_error_name(m_error);
+#else
+  return "__LIBUSB__ not defined";
+#endif
+}
+
+const char* ErrorWrap::GetStrError() const
+{
+#if defined(__LIBUSB__)
+  return libusb_strerror(static_cast<libusb_error>(m_error));
+#else
+  return "__LIBUSB__ not defined";
+#endif
+}
 }  // namespace LibusbUtils

Source/Core/Core/LibusbUtils.h

@@ -3,6 +3,7 @@
 
 #pragma once
 
+#include <fmt/format.h>
 #include <functional>
 #include <memory>
 
@@ -39,4 +40,28 @@ private:
 
 using ConfigDescriptor = UniquePtr<libusb_config_descriptor>;
 ConfigDescriptor MakeConfigDescriptor(libusb_device* device, u8 config_num = 0);
+
+// Wrapper for libusb_error to be used with fmt.  Note that we can't create a fmt::formatter
+// directly for libusb_error as it is a plain enum and most libusb functions actually return an
+// int instead of a libusb_error.
+struct ErrorWrap
+{
+  constexpr explicit ErrorWrap(int error) : m_error(error) {}
+  const int m_error;
+
+  const char* GetStrError() const;
+  const char* GetName() const;
+};
 }  // namespace LibusbUtils
+
+template <>
+struct fmt::formatter<LibusbUtils::ErrorWrap>
+{
+  constexpr auto parse(fmt::format_parse_context& ctx) { return ctx.begin(); }
+  template <typename FormatContext>
+  auto format(const LibusbUtils::ErrorWrap& wrap, FormatContext& ctx) const
+  {
+    return fmt::format_to(ctx.out(), "{} ({}: {})", wrap.GetStrError(), wrap.m_error,
+                          wrap.GetName());
+  }
+};