Workaround transactions recreation issue

packages/hardhat-core/src/internal/hardhat-network/provider/node.ts

@@ -1033,6 +1033,8 @@ Hardhat Network's forking functionality only works with blocks from at least spu
       blockOpts: { calcDifficultyFromHeader: parentBlock.header },
     });
 
+    const transactions = [];
+
     try {
       const traces: GatherTracesResult[] = [];
 
@@ -1053,6 +1055,7 @@ Hardhat Network's forking functionality only works with blocks from at least spu
         if (tx.gasLimit.gt(blockGasLimit.sub(blockBuilder.gasUsed))) {
           txHeap.pop();
         } else {
+          transactions.push(tx);
           const txResult = await blockBuilder.addTransaction(tx);
           const { txReceipt } = await generateTxReceipt.bind(this._vm)(
             tx,
@@ -1078,6 +1081,15 @@ Hardhat Network's forking functionality only works with blocks from at least spu
 
       const block = await blockBuilder.build();
 
+      // We replace the block's transactions with the actual ones,
+      // as the block builder recreates them, turning fake transactions
+      // into real ones.
+      //
+      // IMPORTANT: this workaround only works because while BlockBuilder#addTransaction
+      // recreates the transactions you pass it, it actually runs yours.
+      block.transactions.splice(0);
+      block.transactions.push(...transactions);
+
       await this._txPool.updatePendingAndQueued();
 
       return {

packages/hardhat-core/test/internal/hardhat-network/provider/modules/hardhat.ts

@@ -5,6 +5,7 @@ import {
   numberToRpcQuantity,
   rpcQuantityToNumber,
 } from "../../../../../src/internal/core/jsonrpc/types/base-types";
+import { expectErrorAsync } from "../../../../helpers/errors";
 import { ALCHEMY_URL } from "../../../../setup";
 import { workaroundWindowsCiFailures } from "../../../../utils/workaround-windows-ci-failures";
 import { assertInvalidArgumentsError } from "../../helpers/assertions";
@@ -62,17 +63,46 @@ describe("Hardhat module", function () {
             },
           ]);
 
+          // The tx's msg.sender should be correct during execution
+
+          // msg.sender assertion contract:
+          //
+          // pragma solidity 0.7.0;
+          //
+          // contract C {
+          //     constructor() {
+          //         require(msg.sender == 0xC014BA5EC014ba5ec014Ba5EC014ba5Ec014bA5E);
+          //     }
+          // }
+          const CODE =
+            "0x6080604052348015600f57600080fd5b5073c014ba5ec014ba5ec014ba5ec014ba5ec014ba5e73ffffffffffffffffffffffffffffffffffffffff163373ffffffffffffffffffffffffffffffffffffffff1614605b57600080fd5b603f8060686000396000f3fe6080604052600080fdfea26469706673582212208048da4076c3540ec6ad48a816e6531a302449e979836bd7955dc6bd2c87a52064736f6c63430007000033";
+
           await this.provider.send("hardhat_impersonateAccount", [
             impersonatedAddress,
           ]);
 
-          await this.provider.send("eth_sendTransaction", [
+          await expectErrorAsync(() =>
+            deployContract(this.provider, CODE, DEFAULT_ACCOUNTS_ADDRESSES[0])
+          );
+
+          // deploying with the right address should work
+          await deployContract(this.provider, CODE, impersonatedAddress);
+
+          // Getting the tx through the RPC should give the right from
+
+          const tx = await this.provider.send("eth_sendTransaction", [
             {
               from: impersonatedAddress,
-              to: DEFAULT_ACCOUNTS_ADDRESSES[0],
-              value: "0x10",
+              to: impersonatedAddress,
             },
           ]);
+
+          const receipt = await this.provider.send(
+            "eth_getTransactionReceipt",
+            [tx]
+          );
+
+          assert.equal(receipt.from, impersonatedAddress.toLowerCase());
         });
 
         it("lets you deploy a contract from an impersonated account", async function () {