fix(es/decorators): Fix a regression about class expressions

crates/swc/tests/fixture/issues-4xxx/4063/1/output/index.ts

@@ -17,6 +17,7 @@ define([
     function state() {}
     class Controller {
     }
+    var _cls;
     class _class extends Controller {
         onChange() {}
         constructor(...args){
@@ -26,5 +27,5 @@ define([
     }
     _ts_decorate._([
         state
-    ], _class.prototype, "isTest", void 0);
+    ], _cls.prototype, "isTest", void 0);
 });

crates/swc/tests/fixture/issues-4xxx/4127/1/output/index.ts

@@ -12,8 +12,9 @@ const _ts_decorate = require("@swc/helpers/_/_ts_decorate");
 function test(constructor) {
     console.log(constructor);
 }
+var _cls;
 let _class = class _class {
 };
-_class = _ts_decorate._([
+_cls = _ts_decorate._([
     test
-], _class);
+], _cls);

crates/swc/tests/fixture/issues-4xxx/4127/2/output/index.ts

@@ -2,9 +2,10 @@ import { _ as _ts_decorate } from "@swc/helpers/_/_ts_decorate";
 function test(constructor) {
     console.log(constructor);
 }
+var _cls;
 let _class = class _class {
 };
-_class = _ts_decorate([
+_cls = _ts_decorate([
     test
-], _class);
+], _cls);
 export { _class as default };

crates/swc/tests/fixture/issues-8xxx/8095/es2020/input/.swcrc

@@ -0,0 +1,20 @@
+{
+    "jsc": {
+        "parser": {
+            "syntax": "typescript",
+            "tsx": false,
+            "decorators": true
+        },
+        "target": "es2020",
+        "loose": false,
+        "minify": {
+            "compress": false,
+            "mangle": false
+        }
+    },
+    "module": {
+        "type": "es6"
+    },
+    "minify": false,
+    "isModule": true
+}

crates/swc/tests/fixture/issues-8xxx/8095/es2020/input/1.js

@@ -0,0 +1 @@
+const foo = class { @foo foo(v) { return v } }

crates/swc/tests/fixture/issues-8xxx/8095/es2020/output/1.js

@@ -0,0 +1,10 @@
+import { _ as _ts_decorate } from "@swc/helpers/_/_ts_decorate";
+var _cls;
+const foo = _cls = class _class {
+    foo(v) {
+        return v;
+    }
+};
+_ts_decorate([
+    foo
+], _cls.prototype, "foo", null);

crates/swc/tests/fixture/issues-8xxx/8095/es2022/input/.swcrc

@@ -0,0 +1,20 @@
+{
+    "jsc": {
+        "parser": {
+            "syntax": "typescript",
+            "tsx": false,
+            "decorators": true
+        },
+        "target": "es2022",
+        "loose": false,
+        "minify": {
+            "compress": false,
+            "mangle": false
+        }
+    },
+    "module": {
+        "type": "es6"
+    },
+    "minify": false,
+    "isModule": true
+}

crates/swc/tests/fixture/issues-8xxx/8095/es2022/input/1.js

@@ -0,0 +1 @@
+const foo = class { @foo foo(v) { return v } }

crates/swc/tests/fixture/issues-8xxx/8095/es2022/output/1.js

@@ -0,0 +1,10 @@
+import { _ as _ts_decorate } from "@swc/helpers/_/_ts_decorate";
+var _cls;
+const foo = _cls = class _class {
+    foo(v) {
+        return v;
+    }
+};
+_ts_decorate([
+    foo
+], _cls.prototype, "foo", null);

crates/swc/tests/fixture/issues-8xxx/8095/es5/input/.swcrc

@@ -0,0 +1,20 @@
+{
+    "jsc": {
+        "parser": {
+            "syntax": "typescript",
+            "tsx": false,
+            "decorators": true
+        },
+        "target": "es5",
+        "loose": false,
+        "minify": {
+            "compress": false,
+            "mangle": false
+        }
+    },
+    "module": {
+        "type": "es6"
+    },
+    "minify": false,
+    "isModule": true
+}

crates/swc/tests/fixture/issues-8xxx/8095/es5/input/1.js

@@ -0,0 +1 @@
+const foo = class { @foo foo(v) { return v } }

crates/swc/tests/fixture/issues-8xxx/8095/es5/output/1.js

@@ -0,0 +1,22 @@
+import { _ as _class_call_check } from "@swc/helpers/_/_class_call_check";
+import { _ as _create_class } from "@swc/helpers/_/_create_class";
+import { _ as _ts_decorate } from "@swc/helpers/_/_ts_decorate";
+var _cls;
+var foo = _cls = /*#__PURE__*/ function() {
+    "use strict";
+    function _class() {
+        _class_call_check(this, _class);
+    }
+    _create_class(_class, [
+        {
+            key: "foo",
+            value: function foo(v) {
+                return v;
+            }
+        }
+    ]);
+    return _class;
+}();
+_ts_decorate([
+    foo
+], _cls.prototype, "foo", null);

crates/swc_ecma_transforms/tests/fixture/legacy-only/decl-to-expression/class-decorators/output.ts

@@ -1,5 +1,5 @@
-let A = class A {
-};
+export default class A {
+}
 A = _ts_decorate([
     dec
 ], A);
@@ -8,4 +8,3 @@ let B = class B {
 B = _ts_decorate([
     dec
 ], B);
-export { A as default };

crates/swc_ecma_transforms/tests/fixture/legacy-only/regression-10264/output.ts

@@ -1,7 +1,8 @@
 function myDecorator(decoratee) {}
-let _class = class _class {
+var _cls;
+_cls = class _class {
 };
-_class = _ts_decorate([
+_cls = _ts_decorate([
     myDecorator
-], _class);
-export { _class as default };
+], _cls);
+export { _cls as default };

crates/swc_ecma_transforms/tests/fixture/legacy-only/regression-8041/output.ts

@@ -1,6 +1,8 @@
-export default class _class {
+var _cls;
+_cls = class _class {
     bar() {}
-}
+};
 _ts_decorate([
     foo
-], _class.prototype, "bar", null);
+], _cls.prototype, "bar", null);
+export { _cls as default };

crates/swc_ecma_transforms_proposal/src/decorators/legacy/mod.rs

@@ -30,6 +30,7 @@ pub(super) fn new(metadata: bool) -> TscDecorator {
         class_name: Default::default(),
         constructor_exprs: Default::default(),
         exports: Default::default(),
+        assign_class_expr_to: Default::default(),
     }
 }
 
@@ -49,6 +50,8 @@ pub(super) struct TscDecorator {
     constructor_exprs: Vec<Box<Expr>>,
 
     exports: Vec<ExportSpecifier>,
+
+    assign_class_expr_to: Option<Ident>,
 }
 
 impl TscDecorator {
@@ -291,14 +294,49 @@ impl VisitMut for TscDecorator {
         self.class_name = old;
     }
 
+    fn visit_mut_expr(&mut self, e: &mut Expr) {
+        e.visit_mut_children_with(self);
+
+        if let Some(var_name) = self.assign_class_expr_to.take() {
+            *e = Expr::Assign(AssignExpr {
+                span: DUMMY_SP,
+                op: op!("="),
+                left: var_name.into(),
+                right: Box::new(e.take()),
+            });
+        }
+    }
+
     fn visit_mut_class_expr(&mut self, n: &mut ClassExpr) {
         let old = self.class_name.take();
+
         if contains_decorator(n) && n.ident.is_none() {
-            n.ident = Some(private_ident!("_class"));
-        }
+            let ident = private_ident!("_class");
+
+            let var_name = private_ident!("_cls");
+
+            self.vars.push(VarDeclarator {
+                span: DUMMY_SP,
+                name: Pat::Ident(var_name.clone().into()),
+                init: None,
+                definite: Default::default(),
+            });
+
+            self.class_name = Some(var_name.clone());
+            n.ident = Some(ident);
 
+            n.visit_mut_children_with(self);
+
+            self.class_name = old;
+
+            self.assign_class_expr_to = Some(var_name);
+
+            return;
+        }
         if let Some(ident) = &n.ident {
-            self.class_name = Some(ident.clone());
+            if self.class_name.is_none() {
+                self.class_name = Some(ident.clone());
+            }
         }
 
         n.visit_mut_children_with(self);
@@ -405,6 +443,33 @@ impl VisitMut for TscDecorator {
 
     fn visit_mut_module_item(&mut self, module_item: &mut ModuleItem) {
         match module_item {
+            ModuleItem::ModuleDecl(ModuleDecl::ExportDefaultDecl(ExportDefaultDecl {
+                decl: DefaultDecl::Class(c),
+                ..
+            })) => {
+                c.visit_mut_with(self);
+
+                if let Some(var_name) = self.assign_class_expr_to.take() {
+                    *module_item = ModuleItem::Stmt(
+                        Expr::Assign(AssignExpr {
+                            span: DUMMY_SP,
+                            op: op!("="),
+                            left: var_name.clone().into(),
+                            right: Box::new(Expr::Class(c.take())),
+                        })
+                        .into_stmt(),
+                    );
+
+                    self.exports
+                        .push(ExportSpecifier::Named(ExportNamedSpecifier {
+                            span: DUMMY_SP,
+                            orig: ModuleExportName::Ident(var_name),
+                            exported: Some(ModuleExportName::Ident(quote_ident!("default"))),
+                            is_type_only: Default::default(),
+                        }));
+                }
+            }
+
             ModuleItem::ModuleDecl(ModuleDecl::ExportDecl(n)) => {
                 let export_decl_span = n.span;