fix(es/decorators): Fix init order of 2022-03 impl (#9760)

**Description:**
Fix the order of initialization for 2022-03 decorators. TBH the [proposal](https://github.com/tc39/proposal-decorators) isn't very clear on how `init` is executed for [auto-accessor](https://github.com/tc39/proposal-decorators) decorator


**Related issue:**

 - Closes #9669

Author: jzhan-canva

.changeset/tame-hairs-applaud.md

@@ -0,0 +1,6 @@
+---
+swc_ecma_transforms_proposal: patch
+swc_core: patch
+---
+
+Fix 2022-03 decorators initialization order

crates/swc/tests/fixture/issues-7xxx/7220/1/output/index.js

@@ -14,8 +14,7 @@ var TestClass = /*#__PURE__*/ function() {
     "use strict";
     function TestClass() {
         _class_call_check(this, TestClass);
-        _define_property(this, "calls", []);
-        _initProto(this);
+        _define_property(this, "calls", (_initProto(this), []));
     }
     _create_class(TestClass, [
         {

crates/swc_ecma_transforms_proposal/src/decorator_impl.rs

@@ -51,7 +51,6 @@ struct ClassState {
     /// If not empty, `initProto` should be injected to the constructor.
     init_proto: Option<Ident>,
     init_proto_args: Vec<Option<ExprOrSpread>>,
-    is_init_proto_called: bool,
 
     init_static: Option<Ident>,
     init_static_args: Vec<Option<ExprOrSpread>>,
@@ -718,10 +717,10 @@ impl DecoratorPass {
             }
         }
         body.visit_mut_with(self);
-        c.visit_mut_with(self);
         c.ident = preserved_class_name.clone();
         replace_ident(&mut c.class, c.ident.to_id(), &preserved_class_name);
         c.class.body.extend(body);
+        c.visit_mut_with(self);
         c.class.body.push(ClassMember::StaticBlock(StaticBlock {
             span: DUMMY_SP,
             body: BlockStmt {
@@ -814,19 +813,48 @@ impl VisitMut for DecoratorPass {
 
         n.visit_mut_children_with(self);
 
-        if !self.state.is_init_proto_called {
-            if let Some(init_proto) = self.state.init_proto.clone() {
+        if let Some(init_proto) = self.state.init_proto.clone() {
+            let init_proto_expr = CallExpr {
+                span: DUMMY_SP,
+                callee: init_proto.clone().as_callee(),
+                args: vec![ThisExpr { span: DUMMY_SP }.as_arg()],
+                ..Default::default()
+            };
+            let mut proto_inited = false;
+            for member in n.body.iter_mut() {
+                if let ClassMember::ClassProp(prop) = member {
+                    if prop.is_static {
+                        continue;
+                    }
+                    if let Some(value) = prop.value.clone() {
+                        prop.value = Some(Expr::from_exprs(vec![
+                            init_proto_expr.clone().into(),
+                            value,
+                        ]));
+
+                        proto_inited = true;
+                        break;
+                    }
+                } else if let ClassMember::PrivateProp(prop) = member {
+                    if prop.is_static {
+                        continue;
+                    }
+                    if let Some(value) = prop.value.clone() {
+                        prop.value = Some(Expr::from_exprs(vec![
+                            init_proto_expr.clone().into(),
+                            value,
+                        ]));
+
+                        proto_inited = true;
+                        break;
+                    }
+                }
+            }
+
+            if !proto_inited {
                 let c = self.ensure_constructor(n);
 
-                inject_after_super(
-                    c,
-                    vec![Box::new(Expr::Call(CallExpr {
-                        span: DUMMY_SP,
-                        callee: init_proto.as_callee(),
-                        args: vec![ThisExpr { span: DUMMY_SP }.as_arg()],
-                        ..Default::default()
-                    }))],
-                )
+                inject_after_super(c, vec![Box::new(init_proto_expr.into())])
             }
         }
 
@@ -847,7 +875,6 @@ impl VisitMut for DecoratorPass {
         }
 
         self.state.init_proto = None;
-        self.state.is_init_proto_called = false;
 
         self.state.extra_stmts = old_stmts;
     }
@@ -1045,29 +1072,6 @@ impl VisitMut for DecoratorPass {
                         value: if accessor.decorators.is_empty() {
                             accessor.value
                         } else {
-                            let init_proto =
-                                if self.state.is_init_proto_called || accessor.is_static {
-                                    None
-                                } else {
-                                    self.state.is_init_proto_called = true;
-
-                                    let init_proto = self
-                                        .state
-                                        .init_proto
-                                        .get_or_insert_with(|| private_ident!("_initProto"))
-                                        .clone();
-
-                                    Some(
-                                        CallExpr {
-                                            span: DUMMY_SP,
-                                            callee: init_proto.clone().as_callee(),
-                                            args: vec![ThisExpr { span: DUMMY_SP }.as_arg()],
-                                            ..Default::default()
-                                        }
-                                        .into(),
-                                    )
-                                };
-
                             let init_call = CallExpr {
                                 span: DUMMY_SP,
                                 callee: init.clone().as_callee(),
@@ -1078,9 +1082,7 @@ impl VisitMut for DecoratorPass {
                             }
                             .into();
 
-                            Some(Expr::from_exprs(
-                                init_proto.into_iter().chain(once(init_call)).collect(),
-                            ))
+                            Some(init_call)
                         },
                         type_ann: None,
                         is_static: accessor.is_static,

crates/swc_ecma_transforms_proposal/tests/decorators/2022-03-duplicated-keys/method-and-field/output.js

@@ -2,7 +2,7 @@ var _init_a, _initProto;
 const dec = ()=>{};
 class Foo {
     static{
-        ({ e: [_init_a, _initProto]  } = _apply_decs_2203_r(this, [
+        ({ e: [_init_a, _initProto] } = _apply_decs_2203_r(this, [
             [
                 dec,
                 2,
@@ -15,10 +15,7 @@ class Foo {
             ]
         ], []));
     }
-    constructor(){
-        _initProto(this);
-    }
-    a = _init_a(this, 123);
+    a = (_initProto(this), _init_a(this, 123));
     a() {
         return 1;
     }

crates/swc_ecma_transforms_proposal/tests/decorators/2022-03-getters--to-es2015/private/output.js

@@ -10,8 +10,7 @@ class Foo {
             get: get_a,
             set: void 0
         });
-        _define_property(this, "value", 1);
-        _initProto(this);
+        _define_property(this, "value", (_initProto(this), 1));
     }
 }
 ({ e: [_call_a, _initProto] } = _apply_decs_2203_r(Foo, [

crates/swc_ecma_transforms_proposal/tests/decorators/2022-03-getters--to-es2015/public/output.js

@@ -10,8 +10,7 @@ class Foo {
         return this.value;
     }
     constructor(){
-        _define_property(this, "value", 1);
-        _initProto(this);
+        _define_property(this, "value", (_initProto(this), 1));
     }
 }
 ({ e: [_initProto] } = _apply_decs_2203_r(Foo, [

crates/swc_ecma_transforms_proposal/tests/decorators/2022-03-getters-and-setters--to-es2015/private/output.js

@@ -13,8 +13,7 @@ class Foo {
             get: get_a,
             set: set_a
         });
-        _define_property(this, "value", 1);
-        _initProto(this);
+        _define_property(this, "value", (_initProto(this), 1));
     }
 }
 ({ e: [_call_a, _call_a1, _initProto] } = _apply_decs_2203_r(Foo, [

crates/swc_ecma_transforms_proposal/tests/decorators/2022-03-getters-and-setters--to-es2015/public/output.js

@@ -16,8 +16,7 @@ class Foo {
         this.value = v;
     }
     constructor(){
-        _define_property(this, "value", 1);
-        _initProto(this);
+        _define_property(this, "value", (_initProto(this), 1));
     }
 }
 ({ e: [_initProto] } = _apply_decs_2203_r(Foo, [

crates/swc_ecma_transforms_proposal/tests/decorators/2022-03-getters-and-setters/private/output.js

@@ -21,10 +21,7 @@ class Foo {
             ]
         ], []));
     }
-    constructor(){
-        _initProto(this);
-    }
-    value = 1;
+    value = (_initProto(this), 1);
     get #a() {
         return _call_a(this);
     }

crates/swc_ecma_transforms_proposal/tests/decorators/2022-03-getters-and-setters/public/output.js

@@ -3,7 +3,7 @@ const dec = ()=>{};
 _computedKey = 'b', _computedKey1 = 'b';
 class Foo {
     static{
-        ({ e: [_initProto]  } = _apply_decs_2203_r(this, [
+        ({ e: [_initProto] } = _apply_decs_2203_r(this, [
             [
                 dec,
                 3,
@@ -26,10 +26,7 @@ class Foo {
             ]
         ], []));
     }
-    constructor(){
-        _initProto(this);
-    }
-    value = 1;
+    value = (_initProto(this), 1);
     get a() {
         return this.value;
     }