fix(es/decorators): Fix bugs of 2022-03 implementation (#9145)

**Description:**

I extracted some changes from #8970

Author: kdy1

crates/swc/src/config/mod.rs

@@ -42,6 +42,7 @@ use swc_ecma_minifier::option::terser::TerserTopLevelOptions;
 #[allow(deprecated)]
 pub use swc_ecma_parser::JscTarget;
 use swc_ecma_parser::{parse_file_as_expr, Syntax, TsSyntax};
+pub use swc_ecma_transforms::proposals::DecoratorVersion;
 use swc_ecma_transforms::{
     feature::FeatureFlag,
     hygiene, modules,
@@ -676,6 +677,18 @@ impl Options {
         {
             Box::new(plugin_transforms)
         } else {
+            let decorator_pass: Box<dyn Fold> =
+                match transform.decorator_version.unwrap_or_default() {
+                    DecoratorVersion::V202112 => Box::new(decorators(decorators::Config {
+                        legacy: transform.legacy_decorator.into_bool(),
+                        emit_metadata: transform.decorator_metadata.into_bool(),
+                        use_define_for_class_fields: !assumptions.set_public_class_fields,
+                    })),
+                    DecoratorVersion::V202203 => Box::new(
+                        swc_ecma_transforms::proposals::decorator_2022_03::decorator_2022_03(),
+                    ),
+                };
+
             Box::new(chain!(
                 lint_to_fold(swc_ecma_lints::rules::all(LintParams {
                     program: &program,
@@ -686,23 +699,7 @@ impl Options {
                     source_map: cm.clone(),
                 })),
                 // Decorators may use type information
-                Optional::new(
-                    match transform.decorator_version.unwrap_or_default() {
-                        DecoratorVersion::V202112 => {
-                            Either::Left(decorators(decorators::Config {
-                                legacy: transform.legacy_decorator.into_bool(),
-                                emit_metadata: transform.decorator_metadata.into_bool(),
-                                use_define_for_class_fields: !assumptions.set_public_class_fields,
-                            }))
-                        }
-                        DecoratorVersion::V202203 => {
-                            Either::Right(
-                            swc_ecma_transforms::proposals::decorator_2022_03::decorator_2022_03(),
-                        )
-                        }
-                    },
-                    syntax.decorators()
-                ),
+                Optional::new(decorator_pass, syntax.decorators()),
                 Optional::new(
                     explicit_resource_management(),
                     syntax.explicit_resource_management()
@@ -1446,17 +1443,6 @@ pub struct TransformConfig {
     pub decorator_version: Option<DecoratorVersion>,
 }
 
-#[derive(Debug, Default, Clone, Copy, Serialize, Deserialize)]
-#[serde(deny_unknown_fields, rename_all = "camelCase")]
-pub enum DecoratorVersion {
-    #[default]
-    #[serde(rename = "2021-12")]
-    V202112,
-
-    #[serde(rename = "2022-03")]
-    V202203,
-}
-
 #[derive(Debug, Default, Clone, Serialize, Deserialize, Merge)]
 #[serde(deny_unknown_fields, rename_all = "camelCase")]
 pub struct HiddenTransformConfig {

crates/swc_ecma_transforms_proposal/src/decorator_2022_03.rs

@@ -13,11 +13,11 @@ use swc_ecma_utils::{
 use swc_ecma_visit::{as_folder, noop_visit_mut_type, Fold, VisitMut, VisitMutWith};
 
 pub fn decorator_2022_03() -> impl VisitMut + Fold {
-    as_folder(Decorator202203::default())
+    as_folder(Decorator2022_03::default())
 }
 
 #[derive(Default)]
-struct Decorator202203 {
+struct Decorator2022_03 {
     /// Variables without initializer.
     extra_vars: Vec<VarDeclarator>,
 
@@ -35,6 +35,8 @@ struct Decorator202203 {
 
 #[derive(Default)]
 struct ClassState {
+    private_id_index: u32,
+
     static_lhs: Vec<Ident>,
     proto_lhs: Vec<Ident>,
 
@@ -55,7 +57,7 @@ struct ClassState {
     super_class: Option<Ident>,
 }
 
-impl Decorator202203 {
+impl Decorator2022_03 {
     fn preserve_side_effect_of_decorators(
         &mut self,
         decorators: Vec<Decorator>,
@@ -463,6 +465,7 @@ impl Decorator202203 {
         let has_static_member = body.iter().any(|m| match m {
             ClassMember::Method(m) => m.is_static,
             ClassMember::PrivateMethod(m) => m.is_static,
+            ClassMember::AutoAccessor(m) => m.is_static,
             ClassMember::ClassProp(ClassProp { is_static, .. })
             | ClassMember::PrivateProp(PrivateProp { is_static, .. }) => *is_static,
             ClassMember::StaticBlock(_) => true,
@@ -527,7 +530,9 @@ impl Decorator202203 {
 
             for m in body.iter_mut() {
                 match m {
-                    ClassMember::ClassProp(..) | ClassMember::PrivateProp(..) => {
+                    ClassMember::ClassProp(..)
+                    | ClassMember::PrivateProp(..)
+                    | ClassMember::AutoAccessor(..) => {
                         replace_ident(m, c.ident.to_id(), &new_class_name);
                     }
 
@@ -568,6 +573,13 @@ impl Decorator202203 {
                             p.is_static = false;
                         }
                     }
+
+                    ClassMember::AutoAccessor(p) => {
+                        if p.is_static {
+                            should_move = true;
+                            p.is_static = false;
+                        }
+                    }
                     _ => (),
                 }
 
@@ -753,7 +765,7 @@ impl Decorator202203 {
     }
 }
 
-impl VisitMut for Decorator202203 {
+impl VisitMut for Decorator2022_03 {
     noop_visit_mut_type!();
 
     fn visit_mut_class(&mut self, n: &mut Class) {
@@ -932,6 +944,8 @@ impl VisitMut for Decorator202203 {
         for mut m in members.take() {
             match m {
                 ClassMember::AutoAccessor(mut accessor) => {
+                    accessor.value.visit_mut_with(self);
+
                     let name;
                     let init;
                     let field_name_like: JsWord;
@@ -947,9 +961,14 @@ impl VisitMut for Decorator202203 {
                                 init = private_ident!(format!("_init_{}", k.id.sym));
                                 field_name_like = format!("__{}", k.id.sym).into();
 
+                                self.state.private_id_index += 1;
                                 PrivateName {
                                     span: k.span,
-                                    id: Ident::new(format!("__{}", k.id.sym).into(), k.id.span),
+                                    id: Ident::new(
+                                        format!("__{}_{}", k.id.sym, self.state.private_id_index)
+                                            .into(),
+                                        k.id.span,
+                                    ),
                                 }
                             }
                             Key::Public(k) => {
@@ -958,10 +977,16 @@ impl VisitMut for Decorator202203 {
                                     .replacen("init", "private", 1)
                                     .into();
 
+                                self.state.private_id_index += 1;
+
                                 PrivateName {
                                     span: init.span.with_ctxt(SyntaxContext::empty()),
                                     id: Ident::new(
-                                        field_name_like.clone(),
+                                        format!(
+                                            "{field_name_like}_{}",
+                                            self.state.private_id_index
+                                        )
+                                        .into(),
                                         init.span.with_ctxt(SyntaxContext::empty()),
                                     ),
                                 }
@@ -1310,7 +1335,9 @@ impl VisitMut for Decorator202203 {
 
         for mut m in new.take() {
             match m {
-                ClassMember::Method(..) | ClassMember::PrivateMethod(..) => {}
+                ClassMember::Method(..)
+                | ClassMember::PrivateMethod(..)
+                | ClassMember::AutoAccessor(..) => {}
 
                 _ => {
                     if !m.span().is_dummy() {

crates/swc_ecma_transforms_proposal/src/lib.rs

@@ -1,11 +1,24 @@
 #![deny(clippy::all)]
 #![allow(clippy::vec_box)]
 
+use serde::{Deserialize, Serialize};
+
 pub use self::{
     decorators::decorators, export_default_from::export_default_from,
     import_assertions::import_assertions,
 };
 
+#[derive(Debug, Default, Clone, Copy, Serialize, Deserialize)]
+#[serde(deny_unknown_fields, rename_all = "camelCase")]
+pub enum DecoratorVersion {
+    #[default]
+    #[serde(rename = "2021-12")]
+    V202112,
+
+    #[serde(rename = "2022-03")]
+    V202203,
+}
+
 pub mod decorator_2022_03;
 pub mod decorators;
 pub mod explicit_resource_management;

crates/swc_ecma_transforms_proposal/tests/.gitignore

@@ -0,0 +1,39 @@
+(() => {
+    let old;
+    let block;
+    class Bar {
+    }
+    const dec = (cls, ctx) => {
+        old = cls;
+        return Bar;
+    };
+    const Foo = 
+    @dec
+    class Foo {
+        static { block = Foo; }
+        method() { return Foo; }
+        static method() { return Foo; }
+        field = Foo;
+        static field = Foo;
+        get getter() { return Foo; }
+        static get getter() { return Foo; }
+        set setter(x) { x.foo = Foo; }
+        static set setter(x) { x.foo = Foo; }
+        accessor accessor = Foo;
+        static accessor accessor = Foo;
+    };
+    const foo = new old;
+    let obj;
+    assertEq(() => Foo !== old, true);
+    assertEq(() => Foo, Bar);
+    assertEq(() => block, Bar);
+    assertEq(() => Foo.field, Bar);
+    assertEq(() => foo.field, Bar);
+    assertEq(() => old.getter, Bar);
+    assertEq(() => foo.getter, Bar);
+    assertEq(() => (obj = { foo: null }, old.setter = obj, obj.foo), Bar);
+    assertEq(() => (obj = { foo: null }, foo.setter = obj, obj.foo), Bar);
+    // The specification for accessors is potentially wrong at the moment: https://github.com/tc39/proposal-decorators/issues/529
+    // assertEq(() => old.accessor, Bar)
+    // assertEq(() => foo.accessor, Bar)
+})();

crates/swc_ecma_transforms_proposal/tests/decorator-evanw-split/Class-decorators-Binding-initialization-class-expression.js

@@ -0,0 +1,38 @@
+(() => {
+    let old;
+    let block;
+    class Bar {
+    }
+    const dec = (cls, ctx) => {
+        old = cls;
+        return Bar;
+    };
+    @dec
+    class Foo {
+        static { block = Foo; }
+        method() { return Foo; }
+        static method() { return Foo; }
+        field = Foo;
+        static field = Foo;
+        get getter() { return Foo; }
+        static get getter() { return Foo; }
+        set setter(x) { x.foo = Foo; }
+        static set setter(x) { x.foo = Foo; }
+        accessor accessor = Foo;
+        static accessor accessor = Foo;
+    }
+    const foo = new old;
+    let obj;
+    assertEq(() => Foo !== old, true);
+    assertEq(() => Foo, Bar);
+    assertEq(() => block, Bar);
+    assertEq(() => Foo.field, Bar);
+    assertEq(() => foo.field, Bar);
+    assertEq(() => old.getter, Bar);
+    assertEq(() => foo.getter, Bar);
+    assertEq(() => (obj = { foo: null }, old.setter = obj, obj.foo), Bar);
+    assertEq(() => (obj = { foo: null }, foo.setter = obj, obj.foo), Bar);
+    // The specification for accessors is potentially wrong at the moment: https://github.com/tc39/proposal-decorators/issues/529
+    // assertEq(() => old.accessor, Bar)
+    // assertEq(() => foo.accessor, Bar)
+})();

crates/swc_ecma_transforms_proposal/tests/decorator-evanw-split/Class-decorators-Binding-initialization-class-statement.js

@@ -65,4 +65,23 @@
     assertEq(() => Object.getPrototypeOf(foo), null);
     assertEq(() => order(bar), '0,1,2,3,11,12,13,14,4,5,6,7,15,16,17,18,8,19,9,20,10,21');
     assertEq(() => Object.getPrototypeOf(bar), foo);
+    // Test an undecorated class
+    const FooNoDec = class {
+    };
+    const BarNoDec = class extends FooNoDec {
+    };
+    assertEq(() => FooNoDec[Symbol.metadata], null);
+    assertEq(() => BarNoDec[Symbol.metadata], null);
+    // Test a class with no class decorator
+    const FooOneDec = class {
+        @dec
+        x;
+    };
+    const BarOneDec = class extends FooOneDec {
+        @dec
+        y;
+    };
+    assertEq(() => JSON.stringify(FooOneDec[Symbol.metadata]), JSON.stringify({ x: 22 }));
+    assertEq(() => JSON.stringify(BarOneDec[Symbol.metadata]), JSON.stringify({ y: 23 }));
+    assertEq(() => Object.getPrototypeOf(BarOneDec[Symbol.metadata]), FooOneDec[Symbol.metadata]);
 })();

crates/swc_ecma_transforms_proposal/tests/decorator-evanw-split/Decorator-metadata-class-expression.js

@@ -64,4 +64,23 @@
     assertEq(() => Object.getPrototypeOf(foo), null);
     assertEq(() => order(bar), '0,1,2,3,11,12,13,14,4,5,6,7,15,16,17,18,8,19,9,20,10,21');
     assertEq(() => Object.getPrototypeOf(bar), foo);
+    // Test an undecorated class
+    class FooNoDec {
+    }
+    class BarNoDec extends FooNoDec {
+    }
+    assertEq(() => FooNoDec[Symbol.metadata], null);
+    assertEq(() => BarNoDec[Symbol.metadata], null);
+    // Test a class with no class decorator
+    class FooOneDec {
+        @dec
+        x;
+    }
+    class BarOneDec extends FooOneDec {
+        @dec
+        y;
+    }
+    assertEq(() => JSON.stringify(FooOneDec[Symbol.metadata]), JSON.stringify({ x: 22 }));
+    assertEq(() => JSON.stringify(BarOneDec[Symbol.metadata]), JSON.stringify({ y: 23 }));
+    assertEq(() => Object.getPrototypeOf(BarOneDec[Symbol.metadata]), FooOneDec[Symbol.metadata]);
 })();