feat(no_std): Add no_std support for reth-engine-primitives (#13924)

crates/engine/primitives/Cargo.toml

@@ -32,3 +32,17 @@ futures.workspace = true
 # misc
 serde.workspace = true
 thiserror.workspace = true
+
+[features]
+default = ["std"]
+std = [
+    "reth-execution-types/std",
+    "reth-primitives/std",
+    "reth-primitives-traits/std",
+    "alloy-primitives/std",
+    "alloy-consensus/std",
+    "alloy-rpc-types-engine/std",
+    "futures/std",
+    "serde/std",
+    "thiserror/std",
+]

crates/engine/primitives/src/error.rs

@@ -1,3 +1,4 @@
+use alloc::boxed::Box;
 use alloy_rpc_types_engine::ForkchoiceUpdateError;
 
 /// Represents all error cases when handling a new payload.

crates/engine/primitives/src/event.rs

@@ -1,16 +1,16 @@
 //! Events emitted by the beacon consensus engine.
 
 use crate::ForkchoiceStatus;
+use alloc::{boxed::Box, sync::Arc};
 use alloy_consensus::BlockHeader;
 use alloy_primitives::B256;
 use alloy_rpc_types_engine::ForkchoiceState;
-use reth_primitives::{EthPrimitives, SealedBlock};
+use core::{
-use reth_primitives_traits::{NodePrimitives, SealedHeader};
-use std::{
     fmt::{Display, Formatter, Result},
-    sync::Arc,
     time::Duration,
 };
+use reth_primitives::{EthPrimitives, SealedBlock};
+use reth_primitives_traits::{NodePrimitives, SealedHeader};
 
 /// Events emitted by the consensus engine.
 #[derive(Clone, Debug)]

crates/engine/primitives/src/lib.rs

@@ -7,6 +7,9 @@
 )]
 #![cfg_attr(not(test), warn(unused_crate_dependencies))]
 #![cfg_attr(docsrs, feature(doc_cfg, doc_auto_cfg))]
+#![cfg_attr(not(feature = "std"), no_std)]
+
+extern crate alloc;
 
 mod error;
 

crates/engine/primitives/src/message.rs

@@ -6,15 +6,15 @@ use alloy_rpc_types_engine::{
     ExecutionPayload, ExecutionPayloadSidecar, ForkChoiceUpdateResult, ForkchoiceState,
     ForkchoiceUpdateError, ForkchoiceUpdated, PayloadId, PayloadStatus, PayloadStatusEnum,
 };
-use futures::{future::Either, FutureExt, TryFutureExt};
+use core::{
-use reth_errors::RethResult;
+    fmt::{self, Display},
-use reth_payload_builder_primitives::PayloadBuilderError;
-use std::{
-    fmt::Display,
     future::Future,
     pin::Pin,
     task::{ready, Context, Poll},
 };
+use futures::{future::Either, FutureExt, TryFutureExt};
+use reth_errors::RethResult;
+use reth_payload_builder_primitives::PayloadBuilderError;
 use tokio::sync::{mpsc::UnboundedSender, oneshot};
 
 /// Represents the outcome of forkchoice update.
@@ -168,7 +168,7 @@ pub enum BeaconEngineMessage<Engine: EngineTypes> {
 }
 
 impl<Engine: EngineTypes> Display for BeaconEngineMessage<Engine> {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self {
             Self::NewPayload { payload, .. } => {
                 write!(