AK: Make BigEndian<> and LittleEndian<> work with enum classes

AK/Endian.h

@@ -43,11 +43,11 @@ ALWAYS_INLINE constexpr T convert_between_host_and_little_endian(T value)
     return value;
 #elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
     if constexpr (sizeof(T) == 8)
-        return __builtin_bswap64(value);
+        return static_cast<T>(__builtin_bswap64(static_cast<u64>(value)));
     if constexpr (sizeof(T) == 4)
-        return __builtin_bswap32(value);
+        return static_cast<T>(__builtin_bswap32(static_cast<u32>(value)));
     if constexpr (sizeof(T) == 2)
-        return __builtin_bswap16(value);
+        return static_cast<T>(__builtin_bswap16(static_cast<u16>(value)));
     if constexpr (sizeof(T) == 1)
         return value;
 #endif
@@ -58,11 +58,11 @@ ALWAYS_INLINE constexpr T convert_between_host_and_big_endian(T value)
 {
 #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
     if constexpr (sizeof(T) == 8)
-        return __builtin_bswap64(value);
+        return static_cast<T>(__builtin_bswap64(static_cast<u64>(value)));
     if constexpr (sizeof(T) == 4)
-        return __builtin_bswap32(value);
+        return static_cast<T>(__builtin_bswap32(static_cast<u32>(value)));
     if constexpr (sizeof(T) == 2)
-        return __builtin_bswap16(value);
+        return static_cast<T>(__builtin_bswap16(static_cast<u16>(value)));
     if constexpr (sizeof(T) == 1)
         return value;
 #elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__

Tests/AK/TestEndian.cpp

@@ -15,3 +15,15 @@ static_assert(BigEndian<u32> { 42 } == 42, "Big endian values should be value co
 static_assert(LittleEndian<u32> {} == 0, "Little endian values should be default constructed in a constexpr context.");
 
 static_assert(LittleEndian<u32> { 42 } == 42, "Little endian values should be value constructed in a constexpr context.");
+
+enum class Enum8 : u8 { Element = 1 };
+static_assert(BigEndian<Enum8> { Enum8::Element } == Enum8::Element);
+
+enum class Enum16 : u16 { Element = 2 };
+static_assert(BigEndian<Enum16> { Enum16::Element } == Enum16::Element);
+
+enum class Enum32 : u32 { Element = 3 };
+static_assert(BigEndian<Enum32> { Enum32::Element } == Enum32::Element);
+
+enum class Enum64 : u64 { Element = 4 };
+static_assert(BigEndian<Enum64> { Enum64::Element } == Enum64::Element);