fix: set block.number to l1BlockNumber on arbitrum (foundry-rs#4669)

evm/src/utils.rs

@@ -39,7 +39,6 @@ pub fn apply_chain_and_block_specific_env_changes<T>(env: &mut revm::Env, block:
     if let Ok(chain) = Chain::try_from(env.cfg.chain_id) {
         let block_number = block.number.unwrap_or_default();
 
-        #[allow(clippy::single_match)]
         match chain {
             Chain::Mainnet => {
                 // after merge difficulty is supplanted with prevrandao EIP-4399
@@ -49,6 +48,18 @@ pub fn apply_chain_and_block_specific_env_changes<T>(env: &mut revm::Env, block:
 
                 return
             }
+            Chain::Arbitrum |
+            Chain::ArbitrumGoerli |
+            Chain::ArbitrumNova |
+            Chain::ArbitrumTestnet => {
+                // on arbitrum `block.number` is the L1 block which is included in the
+                // `l1BlockNumber` field
+                if let Some(l1_block_number) = block.other.get("l1BlockNumber").cloned() {
+                    if let Ok(l1_block_number) = serde_json::from_value::<U256>(l1_block_number) {
+                        env.block.number = l1_block_number;
+                    }
+                }
+            }
             _ => {}
         }
     }

forge/tests/it/repros.rs

@@ -96,6 +96,12 @@ fn test_issue_2984() {
     test_repro!("Issue2984");
 }
 
+// <https://github.com/foundry-rs/foundry/issues/4640>
+#[test]
+fn test_issue_4640() {
+    test_repro!("Issue4640");
+}
+
 // <https://github.com/foundry-rs/foundry/issues/3077>
 #[test]
 fn test_issue_3077() {

forge/tests/it/test_helpers.rs

@@ -63,7 +63,7 @@ pub static COMPILED_WITH_LIBS: Lazy<ProjectCompileOutput> = Lazy::new(|| {
 pub static EVM_OPTS: Lazy<EvmOpts> = Lazy::new(|| EvmOpts {
     env: Env {
         gas_limit: 18446744073709551615,
-        chain_id: Some(foundry_common::DEV_CHAIN_ID),
+        chain_id: None,
         tx_origin: Config::DEFAULT_SENDER,
         block_number: 1,
         block_timestamp: 1,

testdata/repros/Issue4640.t.sol

@@ -0,0 +1,17 @@
+// SPDX-License-Identifier: Unlicense
+pragma solidity >=0.8.0;
+
+import "ds-test/test.sol";
+import "../cheats/Cheats.sol";
+
+// https://github.com/foundry-rs/foundry/issues/4640
+contract Issue4640Test is DSTest {
+    Cheats constant vm = Cheats(HEVM_ADDRESS);
+
+    function testArbitrumBlockNumber() public {
+        // <https://arbiscan.io/block/75219831>
+        vm.createSelectFork("https://rpc.ankr.com/arbitrum", 75219831);
+        // L1 block number
+        assertEq(block.number, 16939475);
+    }
+}