From e460f39e9f08dc58d7517c07a23626ab137fd5d0 Mon Sep 17 00:00:00 2001
From: Hadrien Croubois <hadrien.croubois@gmail.com>
Date: Mon, 18 Oct 2021 14:02:45 +0200
Subject: [PATCH] Re-enable immutable forwarder in ERC2771Context

---
 contracts/metatx/ERC2771Context.sol    | 4 ++--
 contracts/mocks/ERC2771ContextMock.sol | 6 ++++--
 hardhat.config.js                      | 2 +-
 3 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/contracts/metatx/ERC2771Context.sol b/contracts/metatx/ERC2771Context.sol
index d6b50a28aac..ae0a284f897 100644
--- a/contracts/metatx/ERC2771Context.sol
+++ b/contracts/metatx/ERC2771Context.sol
@@ -1,6 +1,6 @@
 // SPDX-License-Identifier: MIT
 
-pragma solidity ^0.8.0;
+pragma solidity ^0.8.8;
 
 import "../utils/Context.sol";
 
@@ -8,7 +8,7 @@ import "../utils/Context.sol";
  * @dev Context variant with ERC2771 support.
  */
 abstract contract ERC2771Context is Context {
-    address private _trustedForwarder;
+    address private immutable _trustedForwarder;
 
     constructor(address trustedForwarder) {
         _trustedForwarder = trustedForwarder;
diff --git a/contracts/mocks/ERC2771ContextMock.sol b/contracts/mocks/ERC2771ContextMock.sol
index 7bc1c4538dc..e466c07db21 100644
--- a/contracts/mocks/ERC2771ContextMock.sol
+++ b/contracts/mocks/ERC2771ContextMock.sol
@@ -1,13 +1,15 @@
 // SPDX-License-Identifier: MIT
 
-pragma solidity ^0.8.0;
+pragma solidity ^0.8.8;
 
 import "./ContextMock.sol";
 import "../metatx/ERC2771Context.sol";
 
 // By inheriting from ERC2771Context, Context's internal functions are overridden automatically
 contract ERC2771ContextMock is ContextMock, ERC2771Context {
-    constructor(address trustedForwarder) ERC2771Context(trustedForwarder) {}
+    constructor(address trustedForwarder) ERC2771Context(trustedForwarder) {
+        emit Sender(_msgSender()); // _msgSender() should be accessible during construction
+    }
 
     function _msgSender() internal view virtual override(Context, ERC2771Context) returns (address) {
         return ERC2771Context._msgSender();
diff --git a/hardhat.config.js b/hardhat.config.js
index aaa1ca03606..d12a1914c56 100644
--- a/hardhat.config.js
+++ b/hardhat.config.js
@@ -33,7 +33,7 @@ const argv = require('yargs/yargs')()
     compiler: {
       alias: 'compileVersion',
       type: 'string',
-      default: '0.8.3',
+      default: '0.8.9',
     },
     coinmarketcap: {
       alias: 'coinmarketcapApiKey',