From 72457642702df981714bff727ecd6451aed60e9b Mon Sep 17 00:00:00 2001
From: Brandon Vrooman <brandon.vrooman@gmail.com>
Date: Tue, 7 May 2024 19:48:24 -0400
Subject: [PATCH] Populate prev root from last block before regenesis

---
 crates/chain-config/src/config/state.rs | 3 +++
 crates/fuel-core/src/service/genesis.rs | 8 +++++---
 2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/crates/chain-config/src/config/state.rs b/crates/chain-config/src/config/state.rs
index ffef804f90..a8444d36be 100644
--- a/crates/chain-config/src/config/state.rs
+++ b/crates/chain-config/src/config/state.rs
@@ -89,6 +89,8 @@ pub struct LastBlockConfig {
     pub consensus_parameters_version: ConsensusParametersVersion,
     /// The version of state transition function used to produce last block.
     pub state_transition_version: StateTransitionBytecodeVersion,
+    /// The block id of the last block
+    pub block_hash: Bytes32,
 }
 
 impl From<BlockHeader> for LastBlockConfig {
@@ -108,6 +110,7 @@ impl From<&BlockHeader> for LastBlockConfig {
             state_transition_version: header
                 .application()
                 .state_transition_bytecode_version,
+            block_hash: header.consensus().prev_root,
         }
     }
 }
diff --git a/crates/fuel-core/src/service/genesis.rs b/crates/fuel-core/src/service/genesis.rs
index a1b879adf5..ebaf8d5502 100644
--- a/crates/fuel-core/src/service/genesis.rs
+++ b/crates/fuel-core/src/service/genesis.rs
@@ -178,6 +178,7 @@ pub fn create_genesis_block(config: &Config) -> Block {
     let da_height;
     let consensus_parameters_version;
     let state_transition_bytecode_version;
+    let prev_root;
 
     // If the rollup continues the old rollup, the height of the new block should
     // be higher than that of the old chain by one to make it continuous.
@@ -196,8 +197,8 @@ pub fn create_genesis_block(config: &Config) -> Block {
             .state_transition_version
             .checked_add(1)
             .expect("State transition bytecode version overflow");
-
         da_height = latest_block.da_block_height;
+        prev_root = latest_block.block_hash;
     } else {
         height = 0u32.into();
         #[cfg(feature = "relayer")]
@@ -214,6 +215,7 @@ pub fn create_genesis_block(config: &Config) -> Block {
         }
         consensus_parameters_version = ConsensusParametersVersion::MIN;
         state_transition_bytecode_version = StateTransitionBytecodeVersion::MIN;
+        prev_root = Bytes32::zeroed();
     }
 
     let transactions_ids = vec![];
@@ -228,7 +230,7 @@ pub fn create_genesis_block(config: &Config) -> Block {
                 generated: Empty,
             },
             consensus: ConsensusHeader::<Empty> {
-                prev_root: Bytes32::zeroed(),
+                prev_root,
                 height,
                 time: fuel_core_types::tai64::Tai64::UNIX_EPOCH,
                 generated: Empty,
@@ -291,7 +293,7 @@ mod tests {
     use std::vec;
 
     #[tokio::test]
-    async fn config_initializes_block_height_of_genesic_block() {
+    async fn config_initializes_block_height_of_genesis_block() {
         let block_height = BlockHeight::from(99u32);
         let service_config = Config::local_node_with_state_config(StateConfig {
             last_block: Some(LastBlockConfig {