fix(es/minifier): Fix cycle detection (#10950)

**Description:** The super class expression of a class declaration should be analyzed from the outside context of the class declarartions.

Author: kdy1

.changeset/breezy-experts-complain.md

@@ -0,0 +1,9 @@
+---
+swc_ecma_utils: patch
+swc_core: patch
+swc_ecma_lexer: patch
+swc_ecma_parser: patch
+swc_ecma_usage_analyzer: patch
+---
+
+fix(es/minifier): Fix cycle detection

crates/swc/tests/tsc-references/privateNamesConstructorChain-1.2.minified.js

@@ -1,5 +1,32 @@
 //// [privateNamesConstructorChain-1.ts]
-import "@swc/helpers/_/_class_private_field_get";
-import "@swc/helpers/_/_class_private_field_init";
-import "@swc/helpers/_/_class_private_field_set";
-import "@swc/helpers/_/_class_static_private_field_spec_get";
+import { _ as _class_private_field_get } from "@swc/helpers/_/_class_private_field_get";
+import { _ as _class_private_field_init } from "@swc/helpers/_/_class_private_field_init";
+import { _ as _class_private_field_set } from "@swc/helpers/_/_class_private_field_set";
+import { _ as _class_static_private_field_spec_get } from "@swc/helpers/_/_class_static_private_field_spec_get";
+var _foo = /*#__PURE__*/ new WeakMap();
+class Parent {
+ accessChildProps() {
+ _class_private_field_get(new Child(), _foo), _class_static_private_field_spec_get(Child, Parent, _bar);
+ }
+ constructor(){
+ _class_private_field_init(this, _foo, {
+ writable: !0,
+ value: void 0
+ }), _class_private_field_set(this, _foo, 3);
+ }
+}
+var _bar = {
+ writable: !0,
+ value: 5
+}, _foo1 = /*#__PURE__*/ new WeakMap(), _bar1 = /*#__PURE__*/ new WeakMap();
+class Child extends Parent {
+ constructor(...args){
+ super(...args), _class_private_field_init(this, _foo1, {
+ writable: !0,
+ value: void 0
+ }), _class_private_field_init(this, _bar1, {
+ writable: !0,
+ value: void 0
+ }), _class_private_field_set(this, _foo1, "foo"), _class_private_field_set(this, _bar1, "bar");
+ }
+}

crates/swc_ecma_minifier/tests/fixture/issues/cycle-1/input.js

@@ -0,0 +1,26 @@
+(() => {
+ class A {
+ cycle() {
+ return B;
+ }
+ }
+ class B {
+ cycle() {
+ return A
+ }
+ }
+ 
+ class ExtendsA1 extends sideEffectWith(A) {}
+ class Unused1 {
+ constructor() {
+ ExtendsA1
+ }
+ }
+ class ExtendsA2 extends sideEffectWith(A) {}
+ class Unused2 {
+ async put() {
+ ExtendsA2
+ }
+ }
+ })();
+ 

crates/swc_ecma_minifier/tests/fixture/issues/cycle-1/output.js

@@ -0,0 +1,11 @@
+class A {
+ cycle() {
+ return B;
+ }
+}
+class B {
+ cycle() {
+ return A;
+ }
+}
+sideEffectWith(A), sideEffectWith(A);

crates/swc_ecma_minifier/tests/fixture/issues/cycle-2/input.js

@@ -0,0 +1,20 @@
+
+(() => {
+ class C {
+ cycle() {
+ return D;
+ }
+ }
+ class D {
+ cycle() {
+ return C
+ }
+ }
+ 
+ class ExtendsC extends sideEffectWith(C) {}
+ class Unused {
+ constructor() {
+ ExtendsC
+ }
+ }
+ })();

crates/swc_ecma_minifier/tests/fixture/issues/cycle-2/output.js

@@ -0,0 +1,11 @@
+class C {
+ cycle() {
+ return D;
+ }
+}
+class D {
+ cycle() {
+ return C;
+ }
+}
+sideEffectWith(C);

crates/swc_ecma_transforms_optimization/src/simplify/dce/mod.rs

@@ -471,10 +471,16 @@ impl Visit for Analyzer<'_> {
  }
 
  fn visit_class_decl(&mut self, n: &ClassDecl) {
+ if let Some(super_class) = &n.class.super_class {
+ super_class.visit_with(self);
+ }
+
  self.with_ast_path(vec![n.ident.to_id()], |v| {
  let old = v.cur_class_id.take();
  v.cur_class_id = Some(n.ident.to_id());
- n.visit_children_with(v);
+ n.ident.visit_with(v);
+ n.class.decorators.visit_with(v);
+ n.class.body.visit_with(v);
  v.cur_class_id = old;
 
  if !n.class.decorators.is_empty() {