implicit code_hash issue fixed

light-client-poc/src/circuits/initial_state/circuit.rs

@@ -359,8 +359,6 @@ impl<F: Field> Circuit<F> for InitialStateCircuit<F> {
             vec![q_enable * xnif(is_last_or_padding.expr(), new_root_propagation.expr())]
         });
 
-        /*
-        Note: when there is a non-existing-proof, the state doesn't change
         meta.create_gate(
             "if not last or padding, if state changed in cur row, next row must change state also",
             |meta| {
@@ -380,7 +378,6 @@ impl<F: Field> Circuit<F> for InitialStateCircuit<F> {
                 ]
             },
         );
-        */
 
         meta.create_gate(
             "if not padding and not last row, roots should be chained",

light-client-poc/src/witness/mod.rs

@@ -246,7 +246,12 @@ impl<F: Field> Witness<F> {
             if old.balance != new.balance {
                 changed_values.push(TrieModification::balance(address, new.balance));
             }
-            if old.code_hash != new.code_hash {
+            // If the account has been implicitly created before this code_hash modification
+            // and if this code_hash modification sets it to the default value (which have been
+            // already set implicitly), omit it.
+            let default_code_hash = "0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470";
+            let is_default = new.code_hash == H256::from_str(default_code_hash).unwrap();
+            if old.code_hash != new.code_hash && !is_default {
                 changed_values.push(TrieModification::codehash(address, new.code_hash));
             }