From 1d6cb3517885c1015a6221f1771f18a2d6eff54e Mon Sep 17 00:00:00 2001
From: Paul Lange <palango@gmx.de>
Date: Tue, 7 Nov 2023 16:38:24 +0100
Subject: [PATCH] Clean up `StateTransition` struct

Also change `StateDB` type in `CeloBackend`
---
 core/celo_backend.go     |  3 +--
 core/state_transition.go | 23 +++++++++--------------
 2 files changed, 10 insertions(+), 16 deletions(-)

diff --git a/core/celo_backend.go b/core/celo_backend.go
index 1d5a367d31..370b814d65 100644
--- a/core/celo_backend.go
+++ b/core/celo_backend.go
@@ -6,7 +6,6 @@ import (
 
 	"github.com/ethereum/go-ethereum"
 	"github.com/ethereum/go-ethereum/common"
-	"github.com/ethereum/go-ethereum/core/state"
 	"github.com/ethereum/go-ethereum/core/vm"
 	"github.com/ethereum/go-ethereum/params"
 )
@@ -15,7 +14,7 @@ import (
 // access core contracts during block processing.
 type CeloBackend struct {
 	chainConfig *params.ChainConfig
-	state       *state.StateDB
+	state       vm.StateDB
 }
 
 // ContractCaller implementation
diff --git a/core/state_transition.go b/core/state_transition.go
index 7a5c3b66aa..2151d98b9b 100644
--- a/core/state_transition.go
+++ b/core/state_transition.go
@@ -252,24 +252,15 @@ type StateTransition struct {
 	initialGas   uint64
 	state        vm.StateDB
 	evm          *vm.EVM
-
-	// Celo additions
-	backend *CeloBackend
 }
 
 // NewStateTransition initialises and returns a new state transition object.
 func NewStateTransition(evm *vm.EVM, msg *Message, gp *GasPool) *StateTransition {
-	backend := &CeloBackend{
-		chainConfig: nil,
-		state:       nil,
-	}
-
 	return &StateTransition{
-		gp:      gp,
-		evm:     evm,
-		msg:     msg,
-		state:   evm.StateDB,
-		backend: backend,
+		gp:    gp,
+		evm:   evm,
+		msg:   msg,
+		state: evm.StateDB,
 	}
 }
 
@@ -344,7 +335,11 @@ func (st *StateTransition) canPayFee(checkAmount *big.Int) error {
 			return fmt.Errorf("%w: address %v have %v want %v", ErrInsufficientFunds, st.msg.From.Hex(), balance, checkAmount)
 		}
 	} else {
-		balance, err := contracts.GetBalanceOf(st.backend, st.msg.From, *st.msg.FeeCurrency)
+		backend := &CeloBackend{
+			chainConfig: st.evm.ChainConfig(),
+			state:       st.state,
+		}
+		balance, err := contracts.GetBalanceOf(backend, st.msg.From, *st.msg.FeeCurrency)
 		if err != nil {
 			return err
 		}