From 9f7bedb5680066c79237e85ef30e1849757b55a1 Mon Sep 17 00:00:00 2001
From: alexlamsl <alexlamsl@gmail.com>
Date: Sun, 29 Sep 2024 05:05:45 +0300
Subject: [PATCH] mangle private class properties as local scope

closes #5937
---
 lib/propmangle.js        | 15 ++++++--
 test/compress/classes.js | 80 +++++++++++++++++++++++++++++++++++-----
 2 files changed, 82 insertions(+), 13 deletions(-)

diff --git a/lib/propmangle.js b/lib/propmangle.js
index bd1af120ef..07e2714fce 100644
--- a/lib/propmangle.js
+++ b/lib/propmangle.js
@@ -179,7 +179,7 @@ function mangle_properties(ast, options) {
         reserved.set(name, true);
     });
 
-    var cname = -1;
+    var cname = [ -1, -1 ];
     var cache;
     if (options.cache) {
         cache = options.cache.props;
@@ -245,7 +245,7 @@ function mangle_properties(ast, options) {
     }));
 
     // step 2: renaming properties
-    ast.walk(new TreeWalker(function(node) {
+    ast.walk(new TreeWalker(function(node, descend) {
         if (node instanceof AST_Binary) {
             if (node.operator == "in") mangleStrings(node.left);
         } else if (node.TYPE == "Call") {
@@ -265,6 +265,12 @@ function mangle_properties(ast, options) {
                 mangleStrings(node.args[0]);
                 break;
             }
+        } else if (node instanceof AST_Class) {
+            var save_cname = cname[1];
+            cname[1] = -1;
+            descend();
+            cname[1] = save_cname;
+            return true;
         } else if (node instanceof AST_ClassProperty
             || node instanceof AST_DestructuredKeyVal
             || node instanceof AST_ObjectProperty) {
@@ -331,11 +337,12 @@ function mangle_properties(ast, options) {
                 var debug_mangled = "_$" + name + "$" + debug_suffix + "_";
                 if (can_mangle(debug_mangled)) mangled = debug_mangled;
             }
+            var hash = +/^#/.test(name);
             // either debug mode is off, or it is on and we could not use the mangled name
             if (!mangled) do {
-                mangled = base54(++cname);
+                mangled = base54(++cname[hash]);
             } while (!can_mangle(mangled));
-            if (/^#/.test(name)) mangled = "#" + mangled;
+            if (hash) mangled = "#" + mangled;
             cache.set(name, mangled);
         }
         AST_Node.info("Mapping property {name} to {mangled}", {
diff --git a/test/compress/classes.js b/test/compress/classes.js
index 313e03c377..8bc3f4cee8 100644
--- a/test/compress/classes.js
+++ b/test/compress/classes.js
@@ -2401,31 +2401,93 @@ mangle_properties: {
     expect: {
         class A {
             static #t = "PASS";
-            static get s() {
+            static get t() {
                 return this.#t;
             }
-            #i(t) {
-                return (this["q"] = t) * this.e;
+            #s(t) {
+                return (this["q"] = t) * this.s;
             }
             set q(t) {
-                this.e = t + 1;
+                this.s = t + 1;
             }
-            e = this.#i(6);
+            s = this.#s(6);
         }
-        console.log(A.s, new A().e);
+        console.log(A.t, new A().s);
     }
     expect_stdout: "PASS 42"
     expect_warnings: [
         "INFO: Preserving reserved property q",
         "INFO: Mapping property #P to #t",
-        "INFO: Mapping property Q to s",
-        "INFO: Mapping property #p to #i",
-        "INFO: Mapping property r to e",
+        "INFO: Mapping property Q to t",
+        "INFO: Mapping property #p to #s",
+        "INFO: Mapping property r to s",
         "INFO: Preserving reserved property log",
     ]
     node_version: ">=14.6"
 }
 
+mangle_private_local: {
+    mangle = {
+        properties: {
+            domprops: true,
+        },
+    }
+    input: {
+        class A {
+            p = "foo";
+            #q = "bar";
+            f() {
+                console.log(this.p, this.#q);
+            }
+        }
+        class B {
+            #r = "moo";
+            #g() {
+                return "baz";
+            }
+            h() {
+                console.log(this.#r, this.#g());
+            }
+        }
+        new A().f();
+        new B().h();
+    }
+    expect: {
+        class A {
+            s = "foo";
+            #s = "bar";
+            o() {
+                console.log(this.s, this.#s);
+            }
+        }
+        class B {
+            #s = "moo";
+            #o() {
+                return "baz";
+            }
+            e() {
+                console.log(this.#s, this.#o());
+            }
+        }
+        new A().o();
+        new B().e();
+    }
+    expect_stdout: [
+        "foo bar",
+        "moo baz",
+    ]
+    expect_warnings: [
+        "INFO: Mapping property p to s",
+        "INFO: Mapping property #q to #s",
+        "INFO: Mapping property f to o",
+        "INFO: Preserving reserved property log",
+        "INFO: Mapping property #r to #s",
+        "INFO: Mapping property #g to #o",
+        "INFO: Mapping property h to e",
+    ]
+    node_version: ">=14.6"
+}
+
 issue_4848: {
     options = {
         if_return: true,