From 87c9edbbc74e87fc0cd6a6af54890376d6669ddd Mon Sep 17 00:00:00 2001
From: "Alex Lam S.L" <alexlamsl@gmail.com>
Date: Mon, 17 Jun 2024 04:36:02 +0300
Subject: [PATCH] fix corner case in `unused` (#5847)

fixes #5843
---
 lib/compress.js                 |  6 +++-
 test/compress/default-values.js |  2 +-
 test/compress/destructured.js   | 55 +++++++++++++++++++++++++++++++--
 test/compress/exports.js        |  2 +-
 test/compress/yields.js         |  2 +-
 5 files changed, 61 insertions(+), 6 deletions(-)

diff --git a/lib/compress.js b/lib/compress.js
index 491f26d0..e161f46d 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -8284,6 +8284,7 @@ Compressor.prototype.compress = function(node) {
                             if (prop instanceof AST_Spread) return prop;
                             var key = prop_keys[index];
                             if (key instanceof AST_Node) return prop;
+                            if (key === "__proto__") return prop;
                             if (drop_keys.has(key)) {
                                 var mapped = drop_keys.get(key);
                                 if (!mapped) return prop;
@@ -8317,7 +8318,10 @@ Compressor.prototype.compress = function(node) {
                         if (value.has_side_effects(compressor) && prop.value.match_symbol(function(node) {
                             return node instanceof AST_PropAccess;
                         })) break;
-                        value = make_node(AST_Sub, node, {
+                        value = is_identifier_string(prop.key) ? make_node(AST_Dot, node, {
+                            expression: value,
+                            property: prop.key,
+                        }) : make_node(AST_Sub, node, {
                             expression: value,
                             property: make_node_from_constant(prop.key, prop),
                         });
diff --git a/test/compress/default-values.js b/test/compress/default-values.js
index 4a248d99..aa83b521 100644
--- a/test/compress/default-values.js
+++ b/test/compress/default-values.js
@@ -2293,7 +2293,7 @@ issue_5340_3: {
     }
     expect: {
         var a;
-        (function() {})(a = true["p"]);
+        (function() {})(a = true.p);
         console.log(a);
     }
     expect_stdout: "undefined"
diff --git a/test/compress/destructured.js b/test/compress/destructured.js
index e051541a..55932111 100644
--- a/test/compress/destructured.js
+++ b/test/compress/destructured.js
@@ -1382,7 +1382,7 @@ side_effects_object: {
         }
     }
     expect: {
-        var a = null, c = (console, 42["c"]);
+        var a = null, c = (console, 42..c);
         try {
             c[a = "PASS"];
         } catch (e) {
@@ -1684,7 +1684,7 @@ singleton_1: {
     expect: {
         var b, a = "P"[0], o = {};
         o.p = [ "FAIL"["1"] ][0];
-        o.q = { foo: "S"[0] }["foo"];
+        o.q = { foo: "S"[0] }.foo;
         [ b = "S" ] = [];
         console.log(a + o.p + o.q + b);
     }
@@ -3886,3 +3886,54 @@ issue_5651: {
     expect_stdout: true
     node_version: ">=6"
 }
+
+issue_5843_1: {
+    options = {
+        unused: true,
+    }
+    input: {
+        var { p: a } = {
+            __proto__: {
+                p: "PASS",
+            },
+        };
+        console.log(a);
+    }
+    expect: {
+        var a = {
+            __proto__: {
+                p: "PASS",
+            },
+        }.p;
+        console.log(a);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5843_2: {
+    options = {
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        var a;
+        ({ p: a } = {
+            __proto__: {
+                p: "PASS",
+            },
+        });
+        console.log(a);
+    }
+    expect: {
+        var a;
+        a = {
+            __proto__: {
+                p: "PASS",
+            },
+        }.p;
+        console.log(a);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
diff --git a/test/compress/exports.js b/test/compress/exports.js
index 236a8af4..8523c7f8 100644
--- a/test/compress/exports.js
+++ b/test/compress/exports.js
@@ -260,7 +260,7 @@ hoist_exports_2: {
         }
     }
     expect: {
-        let e, a = 42["foo"];
+        let e, a = 42..foo;
         function f(t, { [e]: o }) {
             t(o, f);
         }
diff --git a/test/compress/yields.js b/test/compress/yields.js
index 933fc295..ab850f06 100644
--- a/test/compress/yields.js
+++ b/test/compress/yields.js
@@ -1386,7 +1386,7 @@ issue_5076_1: {
     expect: {
         var a;
         console.log("PASS"),
-        a = 42["a"];
+        a = 42..a;
     }
     expect_stdout: "PASS"
     node_version: ">=6"