From 61b66e83f1885dd8ad18ff510e38ab601ebf4c5c Mon Sep 17 00:00:00 2001
From: "Alex Lam S.L" <alexlamsl@gmail.com>
Date: Mon, 20 Jul 2020 19:32:20 +0100
Subject: [PATCH] fix corner case in `ie8` (#4016)

fixes #4015
---
 lib/scope.js         |  1 +
 test/compress/ie8.js | 45 ++++++++++++++++++++++++++++++++++++++++++--
 2 files changed, 44 insertions(+), 2 deletions(-)

diff --git a/lib/scope.js b/lib/scope.js
index 66314766..3297b8e6 100644
--- a/lib/scope.js
+++ b/lib/scope.js
@@ -230,6 +230,7 @@ AST_Toplevel.DEFMETHOD("figure_out_scope", function(options) {
         } else {
             new_def = scope.def_variable(node);
         }
+        old_def.defun = new_def.scope;
         old_def.orig.concat(old_def.references).forEach(function(node) {
             node.thedef = new_def;
             node.reference(options);
diff --git a/test/compress/ie8.js b/test/compress/ie8.js
index df06c625..2115dbc6 100644
--- a/test/compress/ie8.js
+++ b/test/compress/ie8.js
@@ -2544,12 +2544,12 @@ issue_3999: {
     expect: {
         (function() {
             (function f() {
-                for (var c = 0; c < 2; c++)
+                for (var o = 0; o < 2; o++)
                     try {
                         f[0];
                     } catch (f) {
                         var f = 0;
-                        console.log(c);
+                        console.log(o);
                     }
             })();
         })(typeof f);
@@ -2593,3 +2593,44 @@ issue_4001: {
     }
     expect_stdout: "undefined"
 }
+
+issue_4015: {
+    rename = true
+    mangle = {
+        ie8: true,
+        toplevel: true,
+    }
+    input: {
+        var n, a = 0, b;
+        function f() {
+            try {
+                throw 0;
+            } catch (b) {
+                (function g() {
+                    (function b() {
+                        a++;
+                    })();
+                })();
+            }
+        }
+        f();
+        console.log(a);
+    }
+    expect: {
+        var n, o = 0, c;
+        function t() {
+            try {
+                throw 0;
+            } catch (c) {
+                (function n() {
+                    (function c() {
+                        o++;
+                    })();
+                })();
+            }
+        }
+        t();
+        console.log(o);
+    }
+    expect_stdout: "1"
+}
-- 
2.34.1