From 9cdc1ef6c2a9684c0ae769ac4ce21c9d593378bb Mon Sep 17 00:00:00 2001
From: "Alex Lam S.L" <alexlamsl@gmail.com>
Date: Wed, 24 Aug 2022 22:01:12 +0100
Subject: [PATCH] fix corner case in `unused` (#5629)

fixes #5628
---
 lib/compress.js          |  2 +-
 test/compress/exports.js | 20 ++++++++++++++++++++
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/lib/compress.js b/lib/compress.js
index 515283f3..22761605 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -6905,7 +6905,7 @@ Compressor.prototype.compress = function(node) {
                     initializations.add(def.id, node);
                     if (tw.parent() instanceof AST_ExportDefault) {
                         export_defaults[def.id] = true;
-                        return;
+                        return scan_ref_scoped(node, descend, true);
                     }
                     if (drop && !(def.id in lambda_ids)) lambda_ids[def.id] = 1;
                     return true;
diff --git a/test/compress/exports.js b/test/compress/exports.js
index a5d0f1bd..236a8af4 100644
--- a/test/compress/exports.js
+++ b/test/compress/exports.js
@@ -560,3 +560,23 @@ issue_5444: {
         export var a = console;
     }
 }
+
+issue_5628: {
+    options = {
+        unused: true,
+    }
+    input: {
+        var a;
+        export default function f() {
+            for (a in 42);
+        }
+        console.log(a);
+    }
+    expect: {
+        var a;
+        export default function f() {
+            for (a in 42);
+        }
+        console.log(a);
+    }
+}