From 1e9b576ee9938d6acb9dff277474e9a32f866690 Mon Sep 17 00:00:00 2001
From: "Alex Lam S.L" <alexlamsl@gmail.com>
Date: Fri, 1 Nov 2019 00:01:25 +0800
Subject: [PATCH] fix corner case in `evaluate` (#3559)

fixes #3558
---
 lib/compress.js           |  8 ++++----
 test/compress/evaluate.js | 21 +++++++++++++++++++++
 2 files changed, 25 insertions(+), 4 deletions(-)

diff --git a/lib/compress.js b/lib/compress.js
index a6f5d20b12..65768c023a 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -2862,10 +2862,10 @@ merge(Compressor.prototype, {
               case "+": return +v;
               case "++":
               case "--":
-                if (e instanceof AST_SymbolRef) {
-                    var refs = e.definition().references;
-                    if (refs[refs.length - 1] === e) return v;
-                }
+                if (!(e instanceof AST_SymbolRef)) return this;
+                var refs = e.definition().references;
+                if (refs[refs.length - 1] !== e) return this;
+                return HOP(e, "_eval") ? +(this.operator[0] + 1) + +v : v;
             }
             return this;
         });
diff --git a/test/compress/evaluate.js b/test/compress/evaluate.js
index 771bd4f6d6..6eadbe514c 100644
--- a/test/compress/evaluate.js
+++ b/test/compress/evaluate.js
@@ -1838,3 +1838,24 @@ recursive_function_2: {
     }
     expect_stdout: "120"
 }
+
+issue_3558: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        toplevel: true,
+    }
+    input: {
+        function f(a) {
+            return 1 + --a;
+        }
+        console.log(f(true), f(false));
+    }
+    expect: {
+        function f(a) {
+            return 1 + --a;
+        }
+        console.log(1, 0);
+    }
+    expect_stdout: "1 0"
+}