Revert "[cxx-interop] Fix assertion failure from unavailable NS_ENUM typedef"

This reverts commit 80db054.

Author: hamishknight

lib/ClangImporter/ImportEnumInfo.cpp

@@ -259,23 +259,10 @@ ImportedType importer::findOptionSetEnum(clang::QualType type,
   if (!clangEnum)
     return ImportedType();
 
-  // Only ASSERT() on assertions-enabled builds. This preserves existing
-  // behavior and de-risks existing builds, but should be removed after 6.2.
-#ifndef NDEBUG
-  // Assert that the typedef has the same underlying integer representation as
-  // the enum we think it assigns a type name to.
-  //
-  // If these fails, it means that we need a stronger predicate for
+  // If this fails, it means that we need a stronger predicate for
   // determining the relationship between an enum and typedef.
-  if (auto *tdEnum =
-          dyn_cast<clang::EnumType>(typedefType->getCanonicalTypeInternal())) {
-    ASSERT(clangEnum.value()->getIntegerType()->getCanonicalTypeInternal() ==
-           tdEnum->getDecl()->getIntegerType()->getCanonicalTypeInternal());
-  } else {
-    ASSERT(clangEnum.value()->getIntegerType()->getCanonicalTypeInternal() ==
-           typedefType->getCanonicalTypeInternal());
-  }
-#endif // !NDEBUG
+  assert(clangEnum.value()->getIntegerType()->getCanonicalTypeInternal() ==
+         typedefType->getCanonicalTypeInternal());
 
   if (auto *swiftEnum = Impl.importDecl(*clangEnum, Impl.CurrentVersion))
     return {cast<TypeDecl>(swiftEnum)->getDeclaredInterfaceType(), false};