fix(es/compat): Hoist env in function params (#4210)

crates/swc/tests/fixture/issues-4xxx/issue-4208/1/input/.swcrc

@@ -0,0 +1,24 @@
+{
+    "jsc": {
+        "externalHelpers": true,
+        "parser": {
+            "syntax": "typescript",
+            "decorators": true,
+            "tsx": true
+        },
+        "transform": {
+            "legacyDecorator": true,
+            "decoratorMetadata": false
+        },
+        "target": "es5",
+        "loose": false,
+        "minify": {
+            "compress": false,
+            "mangle": false
+        }
+    },
+    "module": {
+        "type": "es6"
+    },
+    "minify": false
+}

crates/swc/tests/fixture/issues-4xxx/issue-4208/1/input/index.ts

@@ -0,0 +1,7 @@
+export class CompanyBgStore {
+    public corpName = 123;
+
+    public getBusinessInfo = async (corpName = this.corpName) => {
+        console.log(corpName);
+    };
+}

crates/swc/tests/fixture/issues-4xxx/issue-4208/1/output/index.ts

@@ -0,0 +1,21 @@
+import * as swcHelpers from "@swc/helpers";
+import regeneratorRuntime from "regenerator-runtime";
+export var CompanyBgStore = function CompanyBgStore() {
+    "use strict";
+    swcHelpers.classCallCheck(this, CompanyBgStore);
+    this.corpName = 123;
+    var _this = this;
+    this.getBusinessInfo = swcHelpers.asyncToGenerator(regeneratorRuntime.mark(function _callee() {
+        var corpName, _args = arguments;
+        return regeneratorRuntime.wrap(function _callee$(_ctx) {
+            while(1)switch(_ctx.prev = _ctx.next){
+                case 0:
+                    corpName = _args.length > 0 && _args[0] !== void 0 ? _args[0] : _this.corpName;
+                    console.log(corpName);
+                case 2:
+                case "end":
+                    return _ctx.stop();
+            }
+        }, _callee);
+    }));
+};

crates/swc_ecma_transforms_compat/src/es2017/async_to_generator.rs

@@ -309,7 +309,7 @@ impl Actual {
             Expr::Arrow(arrow_expr @ ArrowExpr { is_async: true, .. }) => {
                 let mut state = FnEnvHoister::default();
 
-                arrow_expr.body.visit_mut_with(&mut state);
+                arrow_expr.visit_mut_with(&mut state);
 
                 self.hoist_stmts.extend(state.to_stmt());
 

crates/swc_ecma_transforms_compat/tests/es2017_async_to_generator.rs

@@ -3557,6 +3557,32 @@ const p = Z((f)=>_asyncToGenerator(function*(n = 0) {
 "
 );
 
+test!(
+    Syntax::default(),
+    |_| async_to_generator(Default::default()),
+    issue_4208,
+    "
+    function foo() {
+        const bar = async (baz = this.baz) => {
+            console.log(this);
+        }
+    }
+    ",
+    "
+    function foo() {
+        var _this = this;
+        const bar = function() {
+            var _ref = _asyncToGenerator(function*(baz = _this.baz) {
+                console.log(_this);
+            });
+            return function bar() {
+                return _ref.apply(this, arguments);
+            };
+        }();
+    }
+    "
+);
+
 #[testing::fixture("tests/async-to-generator/**/exec.js")]
 fn exec(input: PathBuf) {
     let input = read_to_string(&input).unwrap();