From 75e9fd84174eaa8bf97975ad254fe06958564547 Mon Sep 17 00:00:00 2001
From: "Alex Lam S.L" <alexlamsl@gmail.com>
Date: Thu, 17 Dec 2020 05:51:34 +0000
Subject: [PATCH] fix corner case in `arguments` (#4387)

fixes #4386
---
 lib/compress.js               |  2 ++
 test/compress/destructured.js | 20 ++++++++++++++++++++
 2 files changed, 22 insertions(+)

diff --git a/lib/compress.js b/lib/compress.js
index b767264c..a46cd42b 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -9843,6 +9843,8 @@ merge(Compressor.prototype, {
             var argname = fn.argnames[index];
             if (def.deleted && def.deleted[index]) {
                 argname = null;
+            } else if (argname instanceof AST_Destructured) {
+                argname = null;
             } else if (argname && (compressor.has_directive("use strict")
                 || !(fn_parent instanceof AST_Call && index < fn_parent.args.length))) {
                 var arg_def = argname.definition();
diff --git a/test/compress/destructured.js b/test/compress/destructured.js
index 9fd425d1..81beb7f7 100644
--- a/test/compress/destructured.js
+++ b/test/compress/destructured.js
@@ -1866,3 +1866,23 @@ issue_4383: {
     expect_stdout: "1"
     node_version: ">=6"
 }
+
+issue_4386: {
+    options = {
+        arguments: true,
+    }
+    input: {
+        function f({}) {
+            return arguments[0];
+        }
+        console.log(f("PASS"));
+    }
+    expect: {
+        function f({}) {
+            return arguments[0];
+        }
+        console.log(f("PASS"));
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
-- 
2.34.1