From 95657a3b0ce92cb0c029ea99f446b835bcb7bf3c Mon Sep 17 00:00:00 2001
From: overlookmotel <theoverlookmotel@gmail.com>
Date: Sun, 10 Dec 2023 23:16:21 +0000
Subject: [PATCH] Don't freeze temp vars for injecting `this` + `arguments`

---
 lib/serialize/blocks.js |  4 +++-
 test/with.test.js       | 20 ++++++++++----------
 2 files changed, 13 insertions(+), 11 deletions(-)

diff --git a/lib/serialize/blocks.js b/lib/serialize/blocks.js
index d327a809..4dbbb6ba 100644
--- a/lib/serialize/blocks.js
+++ b/lib/serialize/blocks.js
@@ -679,7 +679,9 @@ module.exports = {
 					// Otherwise, can just make `arguments` a normal param.
 					// This can be the case if `arguments` is behind a `with (...)` block,
 					// or `arguments` is a user-defined variable, not `arguments` created by a function.
-					newName = transformVarName(paramName, true);
+					// If block contains a function containing `eval()`, prepend name of temp var with '_'
+					// as it'll be accessible to `eval()`. If param is frozen by `with ()`, this isn't required.
+					newName = transformVarName(paramName, containsEval);
 					if (paramName === 'this') {
 						frozenThisVarName = newName;
 					} else {
diff --git a/test/with.test.js b/test/with.test.js
index aba3a50c..b657de1f 100644
--- a/test/with.test.js
+++ b/test/with.test.js
@@ -81,7 +81,7 @@ describe('with statements', () => {
 					}
 					return outer.call({x: 1});
 				},
-				out: '(_a=>function(){return()=>this}.call(_a))({x:1})',
+				out: '(a=>function(){return()=>this}.call(a))({x:1})',
 				validate(fn) {
 					expect(fn).toBeFunction();
 					expect(fn()).toEqual({x: 1});
@@ -99,11 +99,11 @@ describe('with statements', () => {
 					return outer.call({x: 1});
 				},
 				out: `
-					(y=>_a=>function(){
+					(y=>b=>function(){
 						return a=>{
 							with(a)return()=>[this,y]
 						}
-					}.call(_a))(2)({x:1})({this:3,a:4})
+					}.call(b))(2)({x:1})({this:3,a:4})
 				`,
 				validate(fn) {
 					expect(fn).toBeFunction();
@@ -170,11 +170,11 @@ describe('with statements', () => {
 				},
 				out: `
 					(
-						(_a,_b)=>function(){
+						(b,c)=>function(){
 							return a=>{
 								with(a)return()=>[this,arguments]
 							}
-						}.apply(_a,_b)
+						}.apply(b,c)
 					)({x:1},function(){return arguments}(2,3,4))({a:5})
 				`,
 				validate(fn) {
@@ -201,14 +201,14 @@ describe('with statements', () => {
 				},
 				out: `
 					(
-						(_a,_b)=>function(){
+						(b,c)=>function(){
 							return a=>{
 								with(a)return()=>{
 									"use strict";
 									return[this,arguments]
 								}
 							}
-						}.apply(_a,_b)
+						}.apply(b,c)
 					)({x:1},function(){return arguments}(2,3,4))({a:5})
 				`,
 				validate(fn) {
@@ -232,12 +232,12 @@ describe('with statements', () => {
 			},
 			out: `(()=>{
 				const a=(
-					(_a,b)=>function(){
+					(b,c)=>function(){
 						return[
-							()=>b,
+							()=>c,
 							a=>{with(a)return()=>[x,this]}
 						]
-					}.call(_a)
+					}.call(b)
 				)({y:2},function(){return arguments}(3,4,5));return[a[1]({x:1}),a[0]]
 			})()`,
 			validate([fn1, fn2]) {