Use mem::take instead of mem::replace where appropriate (#5846)

* replace replace with take

* Update client/api/src/cht.rs

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

* Update client/api/src/cht.rs

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

substrate/primitives/core/src/offchain/testing.rs

@@ -105,7 +105,7 @@ impl OffchainState {
 	fn fulfill_expected(&mut self, id: u16) {
 		if let Some(mut req) = self.expected_requests.remove(&RequestId(id)) {
 			let response = req.response.take().expect("Response checked while added.");
-			let headers = std::mem::replace(&mut req.response_headers, vec![]);
+			let headers = std::mem::take(&mut req.response_headers);
 			self.fulfill_pending_request(id, req, response, headers);
 		}
 	}

substrate/primitives/io/src/batch_verifier.rs

@@ -109,13 +109,13 @@ impl BatchVerifier {
 		self.sr25519_items.push(Sr25519BatchItem { signature, pub_key, message });
 
 		if self.sr25519_items.len() >= 128 {
-			let items = std::mem::replace(&mut self.sr25519_items, vec![]);
+			let items = std::mem::take(&mut self.sr25519_items);
 			if self.spawn_verification_task(move || Self::verify_sr25519_batch(items)).is_err() {
 				log::debug!(
 					target: "runtime",
 					"Batch-verification returns false because failed to spawn background task.",
 				);
-	
+
 				return false;
 			}
 		}
@@ -135,7 +135,7 @@ impl BatchVerifier {
 	/// aggregated result.
 	#[must_use]
 	pub fn verify_and_clear(&mut self) -> bool {
-		let pending = std::mem::replace(&mut self.pending_tasks, vec![]);
+		let pending = std::mem::take(&mut self.pending_tasks);
 		let started = std::time::Instant::now();
 
 		log::trace!(
@@ -145,7 +145,7 @@ impl BatchVerifier {
 			self.sr25519_items.len(),
 		);
 
-		if !Self::verify_sr25519_batch(std::mem::replace(&mut self.sr25519_items, vec![])) {
+		if !Self::verify_sr25519_batch(std::mem::take(&mut self.sr25519_items)) {
 			return false;
 		}
 

substrate/primitives/state-machine/src/basic.rs

@@ -82,8 +82,8 @@ impl BasicExternalities {
 	) -> R {
 		let mut ext = Self {
 			inner: Storage {
-				top: std::mem::replace(&mut storage.top, Default::default()),
-				children_default: std::mem::replace(&mut storage.children_default, Default::default()),
+				top: std::mem::take(&mut storage.top),
+				children_default: std::mem::take(&mut storage.children_default),
 			},
 			extensions: Default::default(),
 		};

substrate/primitives/state-machine/src/overlayed_changes.rs

@@ -489,10 +489,10 @@ impl OverlayedChanges {
 	) {
 		assert!(self.prospective.is_empty());
 		(
-			std::mem::replace(&mut self.committed.top, Default::default())
+			std::mem::take(&mut self.committed.top)
 				.into_iter()
 				.map(|(k, v)| (k, v.value)),
-			std::mem::replace(&mut self.committed.children_default, Default::default())
+			std::mem::take(&mut self.committed.children_default)
 				.into_iter()
 				.map(|(sk, (v, ci))| (sk, (v.into_iter().map(|(k, v)| (k, v.value)), ci))),
 		)