make field public

substrate/frame/staking/src/lib.rs

@@ -371,7 +371,7 @@ pub struct ActiveEraInfo {
 	///
 	/// Start can be none if start hasn't been set for the era yet,
 	/// Start is set on the first on_finalize of the era to guarantee usage of `Time`.
-	start: Option<u64>,
+	pub start: Option<u64>,
 }
 
 /// Reward points of an era. Used to split era total payout between validators.