From 4c89550c43974d5d570f132b2d8bc105c05cc618 Mon Sep 17 00:00:00 2001
From: "Alex Lam S.L" <alexlamsl@gmail.com>
Date: Tue, 5 Jan 2021 17:26:19 +0000
Subject: [PATCH] fix corner case in`default_values` (#4511)

fixes #4510
---
 lib/compress.js                 |  3 ++-
 test/compress/default-values.js | 48 +++++++++++++++++++++++++++++++++
 2 files changed, 50 insertions(+), 1 deletion(-)

diff --git a/lib/compress.js b/lib/compress.js
index 1714306e..dcb2cc4c 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -6143,8 +6143,9 @@ merge(Compressor.prototype, {
                     var values = value instanceof AST_Array && value.elements;
                     var elements = [];
                     node.elements.forEach(function(element, index) {
-                        if (element instanceof AST_Hole) return;
                         value = values && values[index];
+                        if (value instanceof AST_Spread) value = values = null;
+                        if (element instanceof AST_Hole) return;
                         element = element.transform(trimmer);
                         if (element) elements[index] = element;
                     });
diff --git a/test/compress/default-values.js b/test/compress/default-values.js
index 0fa27ea5..8e5910d9 100644
--- a/test/compress/default-values.js
+++ b/test/compress/default-values.js
@@ -1479,3 +1479,51 @@ issue_4502_4: {
     expect_stdout: "42"
     node_version: ">=6"
 }
+
+issue_4510_1: {
+    options = {
+        default_values: true,
+        unused: true,
+    }
+    input: {
+        var a = [];
+        var [ , b = console.log("PASS") ] = [ ...a, null ];
+    }
+    expect: {
+        var a = [];
+        var [ , b = console.log("PASS") ] = [ ...a, null ];
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_4510_2: {
+    options = {
+        default_values: true,
+        unused: true,
+    }
+    input: {
+        var o = {
+            p: void 0,
+        };
+        var {
+            p: a = console.log("PASS"),
+        } = {
+            p: null,
+            ...o,
+        };
+    }
+    expect: {
+        var o = {
+            p: void 0,
+        };
+        var {
+            p: a = console.log("PASS"),
+        } = {
+            p: null,
+            ...o,
+        };
+    }
+    expect_stdout: "PASS"
+    node_version: ">=8"
+}
-- 
2.34.1