From 8926a2f327f9954e856161169a92a4190f0318e4 Mon Sep 17 00:00:00 2001
From: "Alex Lam S.L" <alexlamsl@gmail.com>
Date: Tue, 20 Jul 2021 18:10:58 +0100
Subject: [PATCH] fix corner case in `unused` (#5090)

fixes #5089
---
 lib/compress.js            |  2 +-
 test/compress/loops.js     |  4 +--
 test/compress/rests.js     | 55 +++++++++++++++++++++++++++++++++++++-
 test/compress/transform.js |  2 +-
 4 files changed, 58 insertions(+), 5 deletions(-)

diff --git a/lib/compress.js b/lib/compress.js
index c5d75d42..6d1f93d4 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -7276,6 +7276,7 @@ merge(Compressor.prototype, {
             }
 
             function retain_lhs(node) {
+                if (node instanceof AST_DefaultValue) return retain_lhs(node.name);
                 if (node instanceof AST_Destructured) {
                     if (value === null) {
                         value = make_node(AST_Number, node, { value: 0 });
@@ -7289,7 +7290,6 @@ merge(Compressor.prototype, {
                     }
                     return make_node(AST_DestructuredObject, node, { properties: [] });
                 }
-                if (node instanceof AST_DefaultValue) node = node.name;
                 node.__unused = null;
                 return node;
             }
diff --git a/test/compress/loops.js b/test/compress/loops.js
index 034537a6..d5f9269a 100644
--- a/test/compress/loops.js
+++ b/test/compress/loops.js
@@ -193,9 +193,9 @@ evaluate: {
         } while (false);
     }
     expect: {
-        for(;;)
+        for (;;)
             a();
-        for(;;)
+        for (;;)
             c();
         d();
     }
diff --git a/test/compress/rests.js b/test/compress/rests.js
index 18064603..f6878aa8 100644
--- a/test/compress/rests.js
+++ b/test/compress/rests.js
@@ -943,10 +943,63 @@ issue_4666: {
     expect: {
         var a = 0, b = 0;
         var o = (c => +a + c)([ b ]);
-        for(var k in o)
+        for (var k in o)
             b++;
         console.log(1, b);
     }
     expect_stdout: "1 2"
     node_version: ">=6"
 }
+
+issue_5089_1: {
+    options = {
+        unused: true,
+    }
+    input: {
+        var {
+            p: [] = 42,
+            ...o
+        } = {
+            p: [],
+        };
+        console.log(o.p);
+    }
+    expect: {
+        var {
+            p: {},
+            ...o
+        } = {
+            p: 0,
+        };
+        console.log(o.p);
+    }
+    expect_stdout: "undefined"
+    node_version: ">=8"
+}
+
+issue_5089_2: {
+    options = {
+        pure_getters: "strict",
+        unused: true,
+    }
+    input: {
+        var {
+            p: {} = null,
+            ...o
+        } = {
+            p: {},
+        };
+        console.log(o.p);
+    }
+    expect: {
+        var {
+            p: {},
+            ...o
+        } = {
+            p: 0,
+        };
+        console.log(o.p);
+    }
+    expect_stdout: "undefined"
+    node_version: ">=8"
+}
diff --git a/test/compress/transform.js b/test/compress/transform.js
index d8e1ee79..1bee8da9 100644
--- a/test/compress/transform.js
+++ b/test/compress/transform.js
@@ -95,7 +95,7 @@ while_if_break: {
         }
     }
     expect: {
-        for(; a && (b && c && d, !e););
+        for (; a && (b && c && d, !e););
     }
 }