From e13efa0883c06e4349f7e162bde55f088ea99f70 Mon Sep 17 00:00:00 2001
From: Justin Starry <justin@solana.com>
Date: Wed, 13 Apr 2022 12:54:46 +0800
Subject: [PATCH] fix: do not modify transaction during simulation

---
 web3.js/src/connection.ts | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/web3.js/src/connection.ts b/web3.js/src/connection.ts
index 56b407c234..d1dd883874 100644
--- a/web3.js/src/connection.ts
+++ b/web3.js/src/connection.ts
@@ -3878,7 +3878,14 @@ export class Connection {
   ): Promise<RpcResponseAndContext<SimulatedTransactionResponse>> {
     let transaction;
     if (transactionOrMessage instanceof Transaction) {
-      transaction = transactionOrMessage;
+      let originalTx: Transaction = transactionOrMessage;
+      transaction = new Transaction({
+        recentBlockhash: originalTx.recentBlockhash,
+        nonceInfo: originalTx.nonceInfo,
+        feePayer: originalTx.feePayer,
+        signatures: [...originalTx.signatures],
+      });
+      transaction.instructions = transactionOrMessage.instructions;
     } else {
       transaction = Transaction.populate(transactionOrMessage);
     }
@@ -3888,11 +3895,7 @@ export class Connection {
     } else {
       let disableCache = this._disableBlockhashCaching;
       for (;;) {
-        if (!transaction.recentBlockhash) {
-          transaction.recentBlockhash = await this._recentBlockhash(
-            disableCache,
-          );
-        }
+        transaction.recentBlockhash = await this._recentBlockhash(disableCache);
 
         if (!signers) break;