From 1d42e9ad556d6024f58ff3a4fee6df310cbcf34d Mon Sep 17 00:00:00 2001
From: "Alex Lam S.L" <alexlamsl@gmail.com>
Date: Sun, 4 Sep 2022 03:10:31 +0100
Subject: [PATCH] fix corner case in `collapse_vars` (#5644)

fixes #5643
---
 lib/compress.js                |  8 ++++++--
 test/compress/collapse_vars.js | 23 +++++++++++++++++++++++
 2 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/lib/compress.js b/lib/compress.js
index c7f13ed7..56a962c6 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -3416,13 +3416,17 @@ Compressor.prototype.compress = function(node) {
                 if (def.references.length - def.replaced == referenced) return true;
                 if (!def.fixed) return false;
                 if (!lhs.fixed) return false;
+                var assigns = lhs.fixed.assigns;
                 var matched = 0;
                 if (!all(def.references, function(ref, index) {
                     var fixed = ref.fixed;
                     if (!fixed) return false;
                     if (fixed.to_binary || fixed.to_prefix) return false;
-                    if (fixed === lhs.fixed) matched++;
-                    return true;
+                    if (fixed === lhs.fixed) {
+                        matched++;
+                        return true;
+                    }
+                    return assigns && fixed.assigns && assigns[0] !== fixed.assigns[0];
                 })) return false;
                 if (matched != referenced) return false;
                 verify_ref = true;
diff --git a/test/compress/collapse_vars.js b/test/compress/collapse_vars.js
index 4b2fe126..2f96bd77 100644
--- a/test/compress/collapse_vars.js
+++ b/test/compress/collapse_vars.js
@@ -10098,3 +10098,26 @@ issue_5638_4: {
     }
     expect_stdout: "foo 42"
 }
+
+issue_5643: {
+    options = {
+        collapse_vars: true,
+        reduce_vars: true,
+        toplevel: true,
+    }
+    input: {
+        var a = 3, b;
+        a *= 7;
+        b = !!this;
+        console || console.log(b);
+        console.log(a * ++b);
+    }
+    expect: {
+        var a = 3, b;
+        a *= 7;
+        b = !!this;
+        console || console.log(b);
+        console.log(a * ++b);
+    }
+    expect_stdout: "42"
+}