Address comments

core/state/statedb.go

@@ -681,7 +681,7 @@ func (db *StateDB) ForEachStorage(addr common.Address, cb func(key, value common
 
 // copyPredicateStorageSlots creates a deep copy of the provided predicateStorageSlots map.
 func copyPredicateStorageSlots(predicateStorageSlots map[common.Address][]byte) map[common.Address][]byte {
-	res := make(map[common.Address][]byte)
+	res := make(map[common.Address][]byte, len(predicateStorageSlots))
 	for address, slots := range predicateStorageSlots {
 		res[address] = common.CopyBytes(slots)
 	}

precompile/contract/interfaces.go

@@ -22,23 +22,30 @@ type StatefulPrecompiledContract interface {
 
 // PredicateContext provides context to stateful precompile predicates
 type PredicateContext struct {
-	SnowCtx            *snow.Context
+	SnowCtx *snow.Context
+	// Note: ProposerVMBlockCtx may be nil if the Snowman Consensus Engine calls BuildBlock or Verify
+	// instead of BuildBlockWithContext or VerifyWithContext.
+	// In this case, it is up to the precompile to determine if a nil ProposerVMBlockCtx is valid.
 	ProposerVMBlockCtx *block.Context
 }
 
 // Predicater is an optional interface for StatefulPrecompiledContracts to implement.
 // If implemented, the predicate will be enforced on every transaction in a block, prior to the block's execution.
 // If VerifyPredicate returns an error, the block will fail verification with no further processing.
-// WARNING: this is not intended to be used for custom precompiles. Backwards compatibility with custom precompiles that
-// use the Predicater interface will not be supported.
+// Note: ProposerVMBlockCtx may be nil if the engine does not specify it. In this case,
+// it's up to the precompile to determine if a nil ProposerVMBlockCtx is valid.
+// WARNING: If you are implementing a custom precompile, beware that subnet-evm
+// will not maintain backwards compatibility of this interface and your code should not
+// rely on this. Designed for use only by precompiles that ship with subnet-evm.
 type Predicater interface {
 	VerifyPredicate(predicateContext *PredicateContext, storageSlots []byte) error
 }
 
 // Accepter is an optional interface for StatefulPrecompiledContracts to implement.
 // If implemented, Accept will be called for every log with the address of the precompile when the block is accepted.
-// WARNING: this is not intended to be used for custom precompiles. Backwards compatibility with custom precompiles that
-// use the Accepter interface will not be supported.
+// WARNING: If you are implementing a custom precompile, beware that subnet-evm
+// will not maintain backwards compatibility of this interface and your code should not
+// rely on this. Designed for use only by precompiles that ship with subnet-evm.
 type Accepter interface {
 	Accept(txHash common.Hash, logIndex int, topics []common.Hash, logData []byte) error
 }