pallet-evm: configurable gasometer config (#5320)

* pallet-evm: configurable gasometer config

* Bump runtime impl_version

* Update evm to 0.16.1

Documentation updates

Co-authored-by: Gavin Wood <gavin@parity.io>

substrate/frame/evm/src/backend.rs

@@ -7,7 +7,6 @@ use sp_core::{U256, H256, H160};
 use sp_runtime::traits::UniqueSaturatedInto;
 use frame_support::storage::{StorageMap, StorageDoubleMap};
 use sha3::{Keccak256, Digest};
-use evm::Config;
 use evm::backend::{Backend as BackendT, ApplyBackend, Apply};
 use crate::{Trait, Accounts, AccountStorages, AccountCodes, Module, Event};
 
@@ -43,10 +42,6 @@ pub struct Vicinity {
 	pub origin: H160,
 }
 
-/// Gasometer config used for executor. Currently this is hard-coded to
-/// Istanbul hard fork.
-pub static GASOMETER_CONFIG: Config = Config::istanbul();
-
 /// Substrate backend for EVM.
 pub struct Backend<'vicinity, T> {
 	vicinity: &'vicinity Vicinity,

substrate/frame/evm/src/lib.rs

@@ -35,7 +35,7 @@ use sp_runtime::{
 	DispatchResult, traits::{UniqueSaturatedInto, AccountIdConversion, SaturatedConversion},
 };
 use sha3::{Digest, Keccak256};
-use evm::{ExitReason, ExitSucceed, ExitError};
+use evm::{ExitReason, ExitSucceed, ExitError, Config};
 use evm::executor::StackExecutor;
 use evm::backend::ApplyBackend;
 
@@ -116,6 +116,8 @@ impl Precompiles for () {
 	}
 }
 
+static ISTANBUL_CONFIG: Config = Config::istanbul();
+
 /// EVM module trait
 pub trait Trait: frame_system::Trait + pallet_timestamp::Trait {
 	/// Calculator for current gas price.
@@ -128,6 +130,11 @@ pub trait Trait: frame_system::Trait + pallet_timestamp::Trait {
 	type Event: From<Event> + Into<<Self as frame_system::Trait>::Event>;
 	/// Precompiles associated with this EVM engine.
 	type Precompiles: Precompiles;
+
+	/// EVM config used in the module.
+	fn config() -> &'static Config {
+		&ISTANBUL_CONFIG
+	}
 }
 
 decl_storage! {
@@ -381,7 +388,7 @@ impl<T: Trait> Module<T> {
 		let mut executor = StackExecutor::new_with_precompile(
 			&backend,
 			gas_limit as usize,
-			&backend::GASOMETER_CONFIG,
+			T::config(),
 			T::Precompiles::execute,
 		);