From be53c4838b407d3edd61be11ba5f7af3d843f97b Mon Sep 17 00:00:00 2001
From: "Alex Lam S.L" <alexlamsl@gmail.com>
Date: Mon, 6 Jun 2022 16:36:19 +0100
Subject: [PATCH] fix corner case in `collapse_vars` (#5494)

fixes #5493
---
 lib/compress.js         |  1 +
 test/compress/awaits.js | 21 +++++++++++++++++++++
 2 files changed, 22 insertions(+)

diff --git a/lib/compress.js b/lib/compress.js
index 6d9f2c48..27ac4fe9 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -2831,6 +2831,7 @@ Compressor.prototype.compress = function(node) {
                     }
                     return find_stop_logical(parent, op, level);
                 }
+                if (parent instanceof AST_Await) return find_stop_value(parent, level + 1);
                 if (parent instanceof AST_Binary) {
                     var op;
                     if (parent.left === node || !lazy_op[op = parent.operator]) {
diff --git a/test/compress/awaits.js b/test/compress/awaits.js
index 1bc008f9..3a436e72 100644
--- a/test/compress/awaits.js
+++ b/test/compress/awaits.js
@@ -2961,3 +2961,24 @@ issue_5478: {
     expect_stdout: "PASS"
     node_version: ">=8"
 }
+
+issue_5493: {
+    options = {
+        collapse_vars: true,
+        reduce_vars: true,
+    }
+    input: {
+        (async function(a) {
+            var b = await [ 42 || b, a = b ];
+            console.log(a);
+        })();
+    }
+    expect: {
+        (async function(a) {
+            var b = await [ 42 || b, a = b ];
+            console.log(a);
+        })();
+    }
+    expect_stdout: "undefined"
+    node_version: ">=8"
+}