## Enum Case Name

```swift
SWIFT_CC(swift) SWIFT_RUNTIME_STDLIB_INTERFACE
const char *swift_EnumCaseName(OpaqueValue *value, const Metadata *type) {
  // Build a magic mirror. Unconditionally destroy the value at the end.
  const Metadata *mirrorType;
  const OpaqueValue *cMirrorValue;
  std::tie(mirrorType, cMirrorValue) = unwrapExistential(type, value);

  OpaqueValue *mirrorValue = const_cast<OpaqueValue*>(cMirrorValue);
  Mirror mirror;

  bool take = mirrorValue == value;
  ::new (&mirror) MagicMirror(mirrorValue, mirrorType, take);

  MagicMirror *theMirror = reinterpret_cast<MagicMirror *>(&mirror);
  MagicMirrorData data = theMirror->Data;
  const char *result = swift_EnumMirror_caseName(data.Owner, data.Value, data.Type);
  return result;
}
```

```swift
SWIFT_CC(swift) SWIFT_RUNTIME_STDLIB_INTERFACE
const char *swift_EnumMirror_caseName(HeapObject *owner,
                                      const OpaqueValue *value,
                                      const Metadata *type) {
  if (!isEnumReflectable(type)) {
    swift_release(owner);
    return nullptr;
  }

  const auto Enum = static_cast<const EnumMetadata *>(type);
  const auto &Description = Enum->Description->Enum;

  unsigned tag;
  getEnumMirrorInfo(value, type, &tag, nullptr, nullptr);

  swift_release(owner);

  return getFieldName(Description.CaseNames, tag);
}
```