cfg: replace std feature gate alloc imports with extern crate alloc (#10861)

crates/revm/src/batch.rs

@@ -4,14 +4,12 @@ use crate::{
     precompile::{Address, HashSet},
     primitives::alloy_primitives::BlockNumber,
 };
+use alloc::vec::Vec;
 use reth_execution_errors::{BlockExecutionError, InternalBlockExecutionError};
 use reth_primitives::{Receipt, Receipts, Request, Requests};
 use reth_prune_types::{PruneMode, PruneModes, PruneSegmentError, MINIMUM_PRUNING_DISTANCE};
 use revm::db::states::bundle_state::BundleRetention;
 
-#[cfg(not(feature = "std"))]
-use alloc::vec::Vec;
-
 /// Takes care of:
 ///  - recording receipts during execution of multiple blocks.
 ///  - pruning receipts according to the pruning configuration.
@@ -183,14 +181,9 @@ impl BlockBatchRecord {
 #[cfg(test)]
 mod tests {
     use super::*;
+    use alloc::collections::BTreeMap;
     use reth_primitives::{Address, Log, Receipt};
     use reth_prune_types::{PruneMode, ReceiptsLogPruneConfig};
-    #[cfg(feature = "std")]
-    use std::collections::BTreeMap;
-    #[cfg(not(feature = "std"))]
-    extern crate alloc;
-    #[cfg(not(feature = "std"))]
-    use alloc::collections::BTreeMap;
 
     #[test]
     fn test_save_receipts_empty() {

crates/revm/src/lib.rs

@@ -9,7 +9,6 @@
 #![cfg_attr(docsrs, feature(doc_cfg, doc_auto_cfg))]
 #![cfg_attr(not(feature = "std"), no_std)]
 
-#[cfg(not(feature = "std"))]
 extern crate alloc;
 
 /// Contains glue code for integrating reth database into revm's [Database].

crates/revm/src/test_utils.rs

@@ -1,4 +1,5 @@
 use crate::precompile::HashMap;
+use alloc::vec::Vec;
 use reth_primitives::{
     keccak256, Account, Address, BlockNumber, Bytecode, Bytes, StorageKey, B256, U256,
 };
@@ -12,9 +13,6 @@ use reth_trie::{
     HashedStorage,
 };
 
-#[cfg(not(feature = "std"))]
-use alloc::vec::Vec;
-
 /// Mock state for testing
 #[derive(Debug, Default, Clone, Eq, PartialEq)]
 pub struct StateProviderTest {