Cleanup warnings of -Wswitch

Add default branch to the switch-case.

Source/Core/Core/HW/GCMemcard/GCMemcard.cpp

@@ -1108,6 +1108,8 @@ GCMemcardExportFileRetVal GCMemcard::ExportGci(u8 index, const std::string& file
     return GCMemcardExportFileRetVal::FAIL;
   case GCMemcardGetSaveDataRetVal::NOMEMCARD:
     return GCMemcardExportFileRetVal::NOMEMCARD;
+  case GCMemcardGetSaveDataRetVal::SUCCESS:
+    break;
   }
   gci.Seek(DENTRY_SIZE + offset, SEEK_SET);
   for (unsigned int i = 0; i < size; ++i)

Source/Core/Core/HW/SI/SI_DeviceGCSteeringWheel.cpp

@@ -38,9 +38,9 @@ int CSIDevice_GCSteeringWheel::RunBuffer(u8* buffer, int request_length)
     std::memcpy(buffer, &id, sizeof(id));
     return sizeof(id);
   }
+  default:
+    return CSIDevice_GCController::RunBuffer(buffer, request_length);
   }
-
-  return CSIDevice_GCController::RunBuffer(buffer, request_length);
 }
 
 bool CSIDevice_GCSteeringWheel::GetData(u32& hi, u32& low)

Source/Core/DolphinQt/GameList/GameList.cpp

@@ -747,6 +747,7 @@ void GameList::OpenGCSaveFolder()
       break;
     }
     case ExpansionInterface::EXIDEVICE_MEMORYCARD:
+    {
       std::string memcard_path = i == 0 ? Config::Get(Config::MAIN_MEMCARD_A_PATH) :
                                           Config::Get(Config::MAIN_MEMCARD_B_PATH);
 
@@ -756,6 +757,9 @@ void GameList::OpenGCSaveFolder()
       url = QUrl::fromLocalFile(QString::fromStdString(memcard_dir));
       break;
     }
+    default:
+      break;
+    }
 
     found |= !url.isEmpty();
 

Source/Core/VideoCommon/FramebufferShaderGen.cpp

@@ -7,6 +7,8 @@
 #include <sstream>
 #include <string_view>
 
+#include "Common/Logging/Log.h"
+
 #include "VideoCommon/FramebufferManager.h"
 #include "VideoCommon/TextureDecoder.h"
 #include "VideoCommon/VertexShaderGen.h"
@@ -570,6 +572,15 @@ std::string GenerateTextureReinterpretShader(TextureFormat from_format, TextureF
   }
   break;
 
+  case TextureFormat::I4:
+  {
+    ss << "  float4 temp_value = ";
+    EmitTextureLoad(ss, 0, "coords");
+    ss << ";\n"
+          "  raw_value = uint(temp_value.r * 15.0);\n";
+  }
+  break;
+
   case TextureFormat::IA4:
   {
     ss << "  float4 temp_value = ";
@@ -605,6 +616,10 @@ std::string GenerateTextureReinterpretShader(TextureFormat from_format, TextureF
           "  }\n";
   }
   break;
+
+  default:
+    WARN_LOG(VIDEO, "From format %u is not supported", static_cast<u32>(from_format));
+    return "{}\n";
   }
 
   // Now convert it to its new representation.
@@ -654,6 +669,9 @@ std::string GenerateTextureReinterpretShader(TextureFormat from_format, TextureF
           "  }\n";
   }
   break;
+  default:
+    WARN_LOG(VIDEO, "To format %u is not supported", static_cast<u32>(to_format));
+    return "{}\n";
   }
 
   ss << "}\n";