From fc5aee662d99257f59830ebcd5053ead48c9039b Mon Sep 17 00:00:00 2001
From: "Alex Lam S.L" <alexlamsl@gmail.com>
Date: Tue, 5 Jan 2021 06:23:46 +0000
Subject: [PATCH] fix corner case in `merge_vars` (#4505)

fixes #4504
---
 lib/compress.js               | 21 ++++++++++-----------
 test/compress/destructured.js | 26 ++++++++++++++++++++++++++
 2 files changed, 36 insertions(+), 11 deletions(-)

diff --git a/lib/compress.js b/lib/compress.js
index aedbe448..1934ca3d 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -4944,16 +4944,15 @@ merge(Compressor.prototype, {
                         if (node instanceof AST_DestructuredKeyVal) {
                             if (node.key instanceof AST_Node) {
                                 push();
+                                segment.block = node;
                                 node.key.walk(tw);
-                                pop();
-                                push();
                                 node.value.walk(marker);
                                 pop();
                             } else {
                                 node.value.walk(marker);
                             }
                         } else if (node instanceof AST_SymbolRef) {
-                            mark(node, false, true);
+                            mark(node);
                         } else {
                             node.walk(tw);
                         }
@@ -4963,9 +4962,9 @@ merge(Compressor.prototype, {
                     return true;
                 }
                 if (lhs instanceof AST_SymbolRef) {
-                    if (node.operator != "=") mark(lhs, true, false);
+                    if (node.operator != "=") mark(lhs, true);
                     node.right.walk(tw);
-                    mark(lhs, false, true);
+                    mark(lhs);
                     return true;
                 }
                 return;
@@ -5073,7 +5072,7 @@ merge(Compressor.prototype, {
                     var marker = node.uses_arguments && !tw.has_directive("use strict") ? function(node) {
                         if (node instanceof AST_SymbolFunarg) references[node.definition().id] = false;
                     } : function(node) {
-                        if (node instanceof AST_SymbolFunarg) mark(node, false, true);
+                        if (node instanceof AST_SymbolFunarg) mark(node);
                     };
                     var scanner = new TreeWalker(function(ref) {
                         if (ref instanceof AST_SymbolDeclaration) references[ref.definition().id] = false;
@@ -5088,7 +5087,7 @@ merge(Compressor.prototype, {
                         } else {
                             var save = segment;
                             pop();
-                            mark(ref, true, false);
+                            mark(ref, true);
                             segment = save;
                         }
                         return true;
@@ -5125,7 +5124,7 @@ merge(Compressor.prototype, {
                 return true;
             }
             if (node instanceof AST_SymbolRef) {
-                mark(node, true, false);
+                mark(node, true);
                 return true;
             }
             if (node instanceof AST_Try) {
@@ -5153,7 +5152,7 @@ merge(Compressor.prototype, {
                 if (!UNARY_POSTFIX[node.operator]) return;
                 var sym = node.expression;
                 if (!(sym instanceof AST_SymbolRef)) return;
-                mark(sym, true, true);
+                mark(sym, true);
                 return true;
             }
             if (node instanceof AST_VarDef) {
@@ -5161,7 +5160,7 @@ merge(Compressor.prototype, {
                 node.name.mark_symbol(node.value ? function(node) {
                     if (!(node instanceof AST_SymbolDeclaration)) return;
                     if (node instanceof AST_SymbolVar) {
-                        mark(node, false, true);
+                        mark(node, false);
                     } else {
                         references[node.definition().id] = false;
                     }
@@ -5246,7 +5245,7 @@ merge(Compressor.prototype, {
             segment = Object.getPrototypeOf(segment);
         }
 
-        function mark(sym, read, write) {
+        function mark(sym, read) {
             var def = sym.definition(), ldef;
             if (def.id in references) {
                 var refs = references[def.id];
diff --git a/test/compress/destructured.js b/test/compress/destructured.js
index 70c4392a..9812b146 100644
--- a/test/compress/destructured.js
+++ b/test/compress/destructured.js
@@ -2326,3 +2326,29 @@ issue_4500: {
     expect_stdout: "PASS"
     node_version: ">=6"
 }
+
+issue_4504: {
+    options = {
+        inline: true,
+        merge_vars: true,
+    }
+    input: {
+        A = "FAIL";
+        (function f(a) {
+            ({
+                [console.log(a)]: 0[(b => console + b)(A)]
+            } = 0);
+        })("PASS");
+    }
+    expect: {
+        A = "FAIL";
+        (function f(a) {
+            ({
+                [console.log(a)]: 0[b = A, console + b]
+            } = 0);
+            var b;
+        })("PASS");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
-- 
2.34.1