From ea7829daf55f8829cc48466379cc6f6cf3394dbd Mon Sep 17 00:00:00 2001
From: "Alex Lam S.L" <alexlamsl@gmail.com>
Date: Thu, 8 Jul 2021 09:31:04 +0100
Subject: [PATCH] fix corner case in `reduce_vars` (#5062)

fixes #5061
---
 lib/compress.js            |  1 +
 test/compress/functions.js | 52 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 53 insertions(+)

diff --git a/lib/compress.js b/lib/compress.js
index 90261d0a..dbfc2e75 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -889,6 +889,7 @@ merge(Compressor.prototype, {
                     } else {
                         right.parent_scope.resolve().fn_defs.push(right);
                         right.safe_ids = null;
+                        if (!node.write_only) mark_fn_def(tw, ld, right);
                     }
                     return true;
                 } else if (scan) {
diff --git a/test/compress/functions.js b/test/compress/functions.js
index 6d41a265..7c6ebe03 100644
--- a/test/compress/functions.js
+++ b/test/compress/functions.js
@@ -6346,3 +6346,55 @@ issue_5046: {
     }
     expect_stdout: "PASS"
 }
+
+issue_5061_1: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        toplevel: true,
+    }
+    input: {
+        var f, a = 1;
+        (f = function() {
+            console.log(a ? "foo" : "bar");
+        })();
+        f(a = 0);
+    }
+    expect: {
+        var f, a = 1;
+        (f = function() {
+            console.log(a ? "foo" : "bar");
+        })();
+        f(a = 0);
+    }
+    expect_stdout: [
+        "foo",
+        "bar",
+    ]
+}
+
+issue_5061_2: {
+    options = {
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var f, a = 1;
+        (f = function() {
+            console.log(a ? "foo" : "bar");
+        })();
+        f(a = 0);
+    }
+    expect: {
+        var f, a = 1;
+        (f = function() {
+            console.log(a ? "foo" : "bar");
+        })();
+        f(a = 0);
+    }
+    expect_stdout: [
+        "foo",
+        "bar",
+    ]
+}