Derive extra traits for fungibles::Imbalance

prdoc/pr_10587.prdoc

@@ -0,0 +1,10 @@
+title: Derive extra traits for fungibles::Imbalance
+doc:
+- audience: Runtime Dev
+  description: |-
+    This PR adds the same derived traits to `fungibles::Imbalance` that are already derived for `fungible::Imbalance`.
+
+    This is required so that the `OnChargeTransaction` configuration of `pallet_transaction_payment` can work for the `fungibles` version of types/traits (it already works for `fungible`).
+crates:
+- name: frame-support
+  bump: patch

substrate/frame/support/src/traits/tokens/fungibles/imbalance.rs

@@ -21,12 +21,15 @@
 //! See the [`crate::traits::fungibles`] doc for more information about fungibles traits.
 
 use super::*;
-use crate::traits::{
-	fungible,
-	misc::{SameOrOther, TryDrop},
-	tokens::{
-		imbalance::{Imbalance as ImbalanceT, TryMerge},
-		AssetId, Balance,
+use crate::{
+	pallet_prelude::{Decode, DecodeWithMemTracking, Encode, MaxEncodedLen, TypeInfo},
+	traits::{
+		fungible,
+		misc::{SameOrOther, TryDrop},
+		tokens::{
+			imbalance::{Imbalance as ImbalanceT, TryMerge},
+			AssetId, Balance,
+		},
 	},
 };
 use core::marker::PhantomData;
@@ -45,7 +48,16 @@ pub trait HandleImbalanceDrop<AssetId, Balance> {
 ///
 /// Importantly, it has a special `Drop` impl, and cannot be created outside of this module.
 #[must_use]
-#[derive(EqNoBound, PartialEqNoBound, RuntimeDebugNoBound)]
+#[derive(
+	EqNoBound,
+	PartialEqNoBound,
+	RuntimeDebugNoBound,
+	Encode,
+	Decode,
+	DecodeWithMemTracking,
+	MaxEncodedLen,
+	TypeInfo,
+)]
 pub struct Imbalance<
 	A: AssetId,
 	B: Balance,
@@ -84,6 +96,18 @@ impl<
 	}
 }
 
+impl<
+		A: AssetId + Default,
+		B: Balance,
+		OnDrop: HandleImbalanceDrop<A, B>,
+		OppositeOnDrop: HandleImbalanceDrop<A, B>,
+	> Default for Imbalance<A, B, OnDrop, OppositeOnDrop>
+{
+	fn default() -> Self {
+		Self::zero(Default::default())
+	}
+}
+
 impl<
 		A: AssetId,
 		B: Balance,