fix(mangler): mangle private class members used in nested classes properly (#14218)

fixes #14209
refs #14027

Author: sapphi-red

crates/oxc_codegen/src/gen.rs

@@ -2752,11 +2752,9 @@ impl Gen for AccessorProperty<'_> {
 impl Gen for PrivateIdentifier<'_> {
     fn r#gen(&self, p: &mut Codegen, _ctx: Context) {
         let name = if let Some(class_index) = p.current_class_index()
-            && let Some(mangled) = &p
-                .private_member_mappings
-                .as_ref()
-                .and_then(|m| m[class_index].get(self.name.as_str()))
-        {
+            && let Some(mangled) = &p.private_member_mappings.as_ref().and_then(|m| {
+                m[0..=class_index].iter().rev().find_map(|m| m.get(self.name.as_str()))
+            }) {
             (*mangled).clone()
         } else {
             self.name.into_compact_str()

crates/oxc_minifier/tests/mangler/mod.rs

@@ -118,6 +118,8 @@ fn private_member_mangling() {
         "class Foo { #x; check() { return #x in this; } }",
         // Nested classes
         "class Outer { #outerField = 1; inner() { return class Inner { #innerField = 2; get() { return this.#innerField; } }; } }",
+        "class Outer { #shared = 1; getInner() { let self = this; return class { method() { return self.#shared; } }; } }",
+        "class Outer { #shared = 1; getInner() { return class { #shared = 2; method() { return this.#shared; } }; } }",
         // Mixed public and private
         "class Foo { publicField = 1; #privateField = 2; getSum() { return this.publicField + this.#privateField; } }",
         // Test same names across different classes should reuse mangled names

crates/oxc_minifier/tests/mangler/snapshots/private_member_mangling.snap

@@ -60,6 +60,32 @@ class Outer {
 	}
 }
 
+class Outer { #shared = 1; getInner() { let self = this; return class { method() { return self.#shared; } }; } }
+class Outer {
+	#e = 1;
+	getInner() {
+		let e = this;
+		return class {
+			method() {
+				return e.#e;
+			}
+		};
+	}
+}
+
+class Outer { #shared = 1; getInner() { return class { #shared = 2; method() { return this.#shared; } }; } }
+class Outer {
+	#e = 1;
+	getInner() {
+		return class {
+			#e = 2;
+			method() {
+				return this.#e;
+			}
+		};
+	}
+}
+
 class Foo { publicField = 1; #privateField = 2; getSum() { return this.publicField + this.#privateField; } }
 class Foo {
 	publicField = 1;