Add warning comments to RegionSwitch and code that uses it

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

@@ -44,6 +44,7 @@ int GCMemcardDirectory::LoadGCI(const std::string& file_name, DiscIO::Region car
       return NO_INDEX;
     }
 
+    // This isn't a reliable way to detect regions. TODO: Get rid of this?
     DiscIO::Region gci_region = DiscIO::RegionSwitchGC(gci.m_gci_header.Gamecode[3]);
     // Some special save files have game IDs that we parse as UNKNOWN_REGION. For instance:
     // - Datel Action Replay uses C as the fourth character. (Can be on any region's card.)

Source/Core/Core/IOS/ES/Formats.cpp

@@ -232,14 +232,6 @@ u64 TMDReader::GetIOSId() const
   return Common::swap64(m_bytes.data() + offsetof(TMDHeader, ios_id));
 }
 
-DiscIO::Region TMDReader::GetRegion() const
-{
-  if (GetTitleId() == Titles::SYSTEM_MENU)
-    return DiscIO::GetSysMenuRegion(GetTitleVersion());
-
-  return DiscIO::RegionSwitchWii(static_cast<u8>(GetTitleId() & 0xff));
-}
-
 u64 TMDReader::GetTitleId() const
 {
   return Common::swap64(m_bytes.data() + offsetof(TMDHeader, title_id));
@@ -260,6 +252,14 @@ u16 TMDReader::GetGroupId() const
   return Common::swap16(m_bytes.data() + offsetof(TMDHeader, group_id));
 }
 
+DiscIO::Region TMDReader::GetRegion() const
+{
+  if (GetTitleId() == Titles::SYSTEM_MENU)
+    return DiscIO::GetSysMenuRegion(GetTitleVersion());
+
+  return DiscIO::RegionSwitchWii(static_cast<u8>(GetTitleId() & 0xff));
+}
+
 std::string TMDReader::GetGameID() const
 {
   char game_id[6];

Source/Core/Core/IOS/ES/Formats.h

@@ -185,12 +185,14 @@ public:
 
   u16 GetBootIndex() const;
   u64 GetIOSId() const;
-  DiscIO::Region GetRegion() const;
   u64 GetTitleId() const;
   u32 GetTitleFlags() const;
   u16 GetTitleVersion() const;
   u16 GetGroupId() const;
 
+  // Provides a best guess for the region. Might be inaccurate or UNKNOWN_REGION.
+  DiscIO::Region GetRegion() const;
+
   // Constructs a 6-character game ID in the format typically used by Dolphin.
   // If the 6-character game ID would contain unprintable characters,
   // the title ID converted to hexadecimal is returned instead.

Source/Core/DiscIO/Enums.h

@@ -71,11 +71,16 @@ enum class Language
 bool IsDisc(Platform volume_type);
 bool IsWii(Platform volume_type);
 bool IsNTSC(Region region);
+
 Country TypicalCountryForRegion(Region region);
+// Avoid using this function if you can. Country codes aren't always reliable region indicators.
 Region RegionSwitchGC(u8 country_code);
+// Avoid using this function if you can. Country codes aren't always reliable region indicators.
 Region RegionSwitchWii(u8 country_code);
 Country CountrySwitch(u8 country_code);
+
 Region GetSysMenuRegion(u16 title_version);
 std::string GetSysMenuVersionString(u16 title_version);
+
 std::string GetCompanyFromID(const std::string& company_id);
 }

Source/Core/DiscIO/Volume.h

@@ -83,6 +83,7 @@ public:
   virtual Platform GetVolumeType() const = 0;
   virtual bool SupportsIntegrityCheck() const { return false; }
   virtual bool CheckIntegrity(const Partition& partition) const { return false; }
+  // May be inaccurate for WADs
   virtual Region GetRegion() const = 0;
   Country GetCountry() const { return GetCountry(GetGamePartition()); }
   virtual Country GetCountry(const Partition& partition) const = 0;

Source/Core/DiscIO/VolumeWad.h

@@ -50,6 +50,7 @@ public:
     return "";
   }
   Platform GetVolumeType() const override;
+  // Provides a best guess for the region. Might be inaccurate or UNKNOWN_REGION.
   Region GetRegion() const override;
   Country GetCountry(const Partition& partition = PARTITION_NONE) const override;