fix: make the empty array CID const and export it

runtime/Cargo.toml

@@ -14,7 +14,7 @@ fvm_shared = { version = "2.0.0-alpha.2", default-features = false }
 num-traits = "0.2.14"
 num-derive = "0.3.3"
 serde = { version = "1.0.136", features = ["derive"] }
-lazy_static = "1.4.0"
+lazy_static = { version = "1.4.0", optional = true }
 unsigned-varint = "0.7.1"
 integer-encoding = { version = "3.0.3", default-features = false }
 byteorder = "1.4.3"
@@ -78,4 +78,4 @@ no-provider-deal-collateral = []
 # fake proofs (for testing)
 fake-proofs = []
 
-test_utils = ["hex", "multihash/sha2"]
+test_utils = ["hex", "multihash/sha2", "lazy_static"]

runtime/src/runtime/empty.rs

@@ -0,0 +1,37 @@
+use std::mem;
+
+use cid::multihash::Multihash;
+use cid::Cid;
+use fvm_ipld_encoding::DAG_CBOR;
+use fvm_shared::crypto::hash::SupportedHashes;
+
+const fn const_unwrap<T: Copy, E>(r: Result<T, E>) -> T {
+    let v = match r {
+        Ok(r) => r,
+        Err(_) => panic!(),
+    };
+    mem::forget(r);
+    v
+}
+
+// 45b0cfc220ceec5b7c1c62c4d4193d38e4eba48e8815729ce75f9c0ab0e4c1c0
+const EMPTY_ARR_HASH_DIGEST: &[u8] = &[
+    0x45, 0xb0, 0xcf, 0xc2, 0x20, 0xce, 0xec, 0x5b, 0x7c, 0x1c, 0x62, 0xc4, 0xd4, 0x19, 0x3d, 0x38,
+    0xe4, 0xeb, 0xa4, 0x8e, 0x88, 0x15, 0x72, 0x9c, 0xe7, 0x5f, 0x9c, 0x0a, 0xb0, 0xe4, 0xc1, 0xc0,
+];
+
+// bafy2bzacebc3bt6cedhoyw34drrmjvazhu4oj25er2ebk4u445pzycvq4ta4a
+pub const EMPTY_ARR_CID: Cid = Cid::new_v1(
+    DAG_CBOR,
+    const_unwrap(Multihash::wrap(SupportedHashes::Blake2b256 as u64, EMPTY_ARR_HASH_DIGEST)),
+);
+
+#[test]
+fn test_empty_arr_cid() {
+    use cid::multihash::{Code, MultihashDigest};
+    use fvm_ipld_encoding::to_vec;
+
+    let empty = to_vec::<[(); 0]>(&[]).unwrap();
+    let expected = Cid::new_v1(DAG_CBOR, Code::Blake2b256.digest(&empty));
+    assert_eq!(EMPTY_ARR_CID, expected);
+}

runtime/src/runtime/fvm.rs

@@ -1,8 +1,8 @@
 use anyhow::{anyhow, Error};
-use cid::multihash::{Code, MultihashDigest};
+use cid::multihash::Code;
 use cid::Cid;
 use fvm_ipld_blockstore::Blockstore;
-use fvm_ipld_encoding::{to_vec, Cbor, CborStore, RawBytes, DAG_CBOR};
+use fvm_ipld_encoding::{Cbor, CborStore, RawBytes, DAG_CBOR};
 use fvm_sdk as fvm;
 use fvm_sdk::NO_DATA_BLOCK_ID;
 use fvm_shared::address::Address;
@@ -30,13 +30,7 @@ use crate::runtime::{
 };
 use crate::{actor_error, ActorError, Runtime};
 
-lazy_static::lazy_static! {
-    /// Cid of the empty array Cbor bytes (`EMPTY_ARR_BYTES`).
-    pub static ref EMPTY_ARR_CID: Cid = {
-        let empty = to_vec::<[(); 0]>(&[]).unwrap();
-        Cid::new_v1(DAG_CBOR, Code::Blake2b256.digest(&empty))
-    };
-}
+use super::EMPTY_ARR_CID;
 
 /// A runtime that bridges to the FVM environment through the FVM SDK.
 pub struct FvmRuntime<B = ActorBlockstore> {
@@ -231,7 +225,7 @@ where
 
     fn create<C: Cbor>(&mut self, obj: &C) -> Result<(), ActorError> {
         let root = fvm::sself::root()?;
-        if root != *EMPTY_ARR_CID {
+        if root != EMPTY_ARR_CID {
             return Err(
                 actor_error!(illegal_state; "failed to create state; expected empty array CID, got: {}", root),
             );

runtime/src/runtime/mod.rs

@@ -34,6 +34,9 @@ mod actor_blockstore;
 #[cfg(feature = "fil-actor")]
 pub mod fvm;
 
+pub(crate) mod empty;
+pub use empty::EMPTY_ARR_CID;
+
 /// Runtime is the VM's internal runtime object.
 /// this is everything that is accessible to actors, beyond parameters.
 pub trait Runtime<BS: Blockstore>: Primitives + Verifier + RuntimePolicy {

test_vm/src/lib.rs

@@ -17,7 +17,7 @@ use fil_actors_runtime::cbor::serialize;
 use fil_actors_runtime::runtime::builtins::Type;
 use fil_actors_runtime::runtime::{
     ActorCode, DomainSeparationTag, MessageInfo, Policy, Primitives, Runtime, RuntimePolicy,
-    Verifier,
+    Verifier, EMPTY_ARR_CID,
 };
 use fil_actors_runtime::test_utils::*;
 use fil_actors_runtime::MessageAccumulator;
@@ -66,7 +66,6 @@ pub struct VM<'bs> {
     total_fil: TokenAmount,
     actors_dirty: RefCell<bool>,
     actors_cache: RefCell<HashMap<Address, Actor>>,
-    empty_obj_cid: Cid,
     network_version: NetworkVersion,
     curr_epoch: ChainEpoch,
     invocations: RefCell<Vec<InvocationTrace>>,
@@ -111,14 +110,12 @@ pub const FIRST_TEST_USER_ADDR: ActorID = FIRST_NON_SINGLETON_ADDR + 3;
 impl<'bs> VM<'bs> {
     pub fn new(store: &'bs MemoryBlockstore) -> VM<'bs> {
         let mut actors = Hamt::<&'bs MemoryBlockstore, Actor, BytesKey, Sha256>::new(store);
-        let empty = store.put_cbor(&(), Code::Blake2b256).unwrap();
         VM {
             store,
             state_root: RefCell::new(actors.flush().unwrap()),
             total_fil: TokenAmount::zero(),
             actors_dirty: RefCell::new(false),
             actors_cache: RefCell::new(HashMap::new()),
-            empty_obj_cid: empty,
             network_version: NetworkVersion::V16,
             curr_epoch: ChainEpoch::zero(),
             invocations: RefCell::new(vec![]),
@@ -256,7 +253,6 @@ impl<'bs> VM<'bs> {
             total_fil: self.total_fil,
             actors_dirty: RefCell::new(false),
             actors_cache: RefCell::new(HashMap::new()),
-            empty_obj_cid: self.empty_obj_cid,
             network_version: self.network_version,
             curr_epoch: epoch,
             invocations: RefCell::new(vec![]),
@@ -683,7 +679,7 @@ impl<'invocation, 'bs> Runtime<&'bs MemoryBlockstore> for InvocationCtx<'invocat
                 "attempt to create new actor at existing address".to_string(),
             ));
         }
-        let a = actor(code_id, self.v.empty_obj_cid, 0, TokenAmount::zero());
+        let a = actor(code_id, EMPTY_ARR_CID, 0, TokenAmount::zero());
         self.v.set_actor(addr, a);
         Ok(())
     }
@@ -838,7 +834,7 @@ impl<'invocation, 'bs> Runtime<&'bs MemoryBlockstore> for InvocationCtx<'invocat
                 "failed to create state".to_string(),
             )),
             Some(mut act) => {
-                if act.head != self.v.empty_obj_cid {
+                if act.head != EMPTY_ARR_CID {
                     Err(ActorError::unchecked(
                         ExitCode::SYS_ASSERTION_FAILED,
                         "failed to construct state: already initialized".to_string(),