fix

tokens/src/imbalances.rs

@@ -1,7 +1,7 @@
 // wrapping these imbalances in a private module is necessary to ensure absolute
 // privacy of the inner member.
 use crate::{Config, TotalIssuance};
-use frame_support::traits::{Get, Imbalance, SameOrOther, TryDrop};
+use frame_support::traits::{tokens::imbalance::TryMerge, Get, Imbalance, SameOrOther, TryDrop};
 use sp_runtime::traits::{Saturating, Zero};
 use sp_std::{marker, mem, result};
 
@@ -184,3 +184,14 @@ impl<T: Config, GetCurrencyId: Get<T::CurrencyId>> Drop for NegativeImbalance<T,
 		TotalIssuance::<T>::mutate(GetCurrencyId::get(), |v| *v = v.saturating_sub(self.0));
 	}
 }
+
+impl<T: Config, GetCurrencyId: Get<T::CurrencyId>> TryMerge for PositiveImbalance<T, GetCurrencyId> {
+	fn try_merge(self, other: Self) -> Result<Self, (Self, Self)> {
+		Ok(self.merge(other))
+	}
+}
+impl<T: Config, GetCurrencyId: Get<T::CurrencyId>> TryMerge for NegativeImbalance<T, GetCurrencyId> {
+	fn try_merge(self, other: Self) -> Result<Self, (Self, Self)> {
+		Ok(self.merge(other))
+	}
+}