--- /absl/base/options.h	2021-06-30 10:39:27.504944873 +0900
+++ /absl/base/options.h	2021-06-30 10:40:00.293122622 +0900
@@ -127,7 +127,7 @@
 // absl::optional is a typedef of std::optional, use the feature macro
 // ABSL_USES_STD_OPTIONAL.
 
-#define ABSL_OPTION_USE_STD_OPTIONAL 2
+#define ABSL_OPTION_USE_STD_OPTIONAL 1
 
 
 // ABSL_OPTION_USE_STD_STRING_VIEW