fix(es/compat): Handle useDefineForClassFields: false (#7055)

**BREAKING CHANGE:**

IMPORTANT NOTE: Users of decorators are recommended to configure `"useDefineForClassFields": false` to ensure that your code is properly transpiled.


**Related issue:**
 - Closes #6985.

Author: magic-akari

crates/swc/src/builder.rs

@@ -213,6 +213,10 @@ impl<'a, 'b, P: swc_ecma_visit::Fold> PassBuilder<'a, 'b, P> {
             feature_flag = enable_available_feature_from_es_version(self.target);
 
             Either::Right(chain!(
+                Optional::new(
+                    compat::class_fields_use_set::class_fields_use_set(assumptions.pure_getters),
+                    assumptions.set_public_class_fields,
+                ),
                 Optional::new(
                     compat::es2022::es2022(
                         comments,

crates/swc/src/config/mod.rs

@@ -363,10 +363,10 @@ impl Options {
         // variable management system based on the syntax contexts.
         if syntax.typescript() {
             assumptions.set_class_methods = !transform.use_define_for_class_fields.into_bool();
-            assumptions.set_public_class_fields =
-                !transform.use_define_for_class_fields.into_bool();
         }
 
+        assumptions.set_public_class_fields = !transform.use_define_for_class_fields.into_bool();
+
         program.visit_mut_with(&mut resolver(
             unresolved_mark,
             top_level_mark,
@@ -669,7 +669,6 @@ impl Options {
                                 .into_bool(),
                             ts_enum_is_readonly: assumptions.ts_enum_is_readonly,
                         },
-                        use_define_for_class_fields: !assumptions.set_public_class_fields,
                         import_export_assign_config,
                         ..Default::default()
                     },
@@ -1478,7 +1477,7 @@ pub struct TransformConfig {
     pub treat_const_enum_as_enum: BoolConfig<false>,
 
     #[serde(default)]
-    pub use_define_for_class_fields: BoolConfig<false>,
+    pub use_define_for_class_fields: BoolConfig<true>,
 }
 
 #[derive(Debug, Default, Clone, Serialize, Deserialize, Merge)]

crates/swc/tests/exec.rs

@@ -8,7 +8,10 @@ use std::{
 use anyhow::{Context, Error};
 use once_cell::sync::Lazy;
 use swc::{
-    config::{Config, JsMinifyOptions, JscConfig, ModuleConfig, Options, SourceMapsConfig},
+    config::{
+        Config, JsMinifyOptions, JscConfig, ModuleConfig, Options, SourceMapsConfig,
+        TransformConfig,
+    },
     try_with_handler, BoolOrDataConfig, Compiler, HandlerOpts,
 };
 use swc_common::{errors::ColorConfig, SourceMap, GLOBALS};
@@ -113,10 +116,7 @@ fn init_helpers() -> Arc<PathBuf> {
 }
 
 fn create_matrix(entry: &Path) -> Vec<Options> {
-    // use_define_for_class_fields: false
-    // force to use [[Set]] instead of [[Define]]
-    // EsVersion should be lower than EsVersion::Es2022
-    let force_set_class_field = entry
+    let use_define_for_class_fields = entry
         .parent()
         .map(|parent| parent.join(".swcrc"))
         .and_then(|path| fs::read_to_string(path).ok())
@@ -133,8 +133,8 @@ fn create_matrix(entry: &Path) -> Vec<Options> {
         })
         .and_then(|content| serde_json::from_value::<Config>(content).ok())
         .and_then(|config| config.jsc.transform.into_inner())
-        .map(|c| c.use_define_for_class_fields == false.into())
-        .unwrap_or(false);
+        .map(|c| c.use_define_for_class_fields)
+        .unwrap_or_default();
 
     [
         EsVersion::Es2022,
@@ -148,7 +148,6 @@ fn create_matrix(entry: &Path) -> Vec<Options> {
         EsVersion::Es5,
     ]
     .into_iter()
-    .filter(|e| !force_set_class_field || e < &EsVersion::Es2022)
     .matrix(|| {
         let default_es = Syntax::Es(EsConfig {
             ..Default::default()
@@ -177,7 +176,11 @@ fn create_matrix(entry: &Path) -> Vec<Options> {
                 config: Config {
                     jsc: JscConfig {
                         syntax: Some(syntax),
-                        transform: None.into(),
+                        transform: Some(TransformConfig {
+                            use_define_for_class_fields,
+                            ..Default::default()
+                        })
+                        .into(),
                         // true, false
                         external_helpers: (!external_helpers).into(),
                         target: Some(target),
@@ -307,11 +310,19 @@ fn get_expected_stdout(input: &Path) -> Result<String, Error> {
                         &Options {
                             config: Config {
                                 jsc: JscConfig {
-                                    target: Some(EsVersion::Es2021),
+                                    target: Some(EsVersion::Es2022),
                                     syntax: Some(Syntax::Typescript(TsConfig {
                                         decorators: true,
                                         ..Default::default()
                                     })),
+                                    transform: Some(TransformConfig {
+                                        use_define_for_class_fields: (!input
+                                            .to_string_lossy()
+                                            .contains("set_public_class_fields"))
+                                        .into(),
+                                        ..Default::default()
+                                    })
+                                    .into(),
                                     ..Default::default()
                                 },
                                 module: match input.extension() {

crates/swc/tests/exec/issues-1xxx/1592/.swcrc renamed to crates/swc/tests/exec/issues-1xxx/1592/set_public_class_fields/.swcrc

@@ -12,7 +12,8 @@
         },
         "transform": {
             "legacyDecorator": true,
-            "decoratorMetadata": true
+            "decoratorMetadata": true,
+            "useDefineForClassFields": false
         }
     },
     "module": {

crates/swc/tests/exec/issues-1xxx/1592/exec.ts renamed to crates/swc/tests/exec/issues-1xxx/1592/set_public_class_fields/exec.ts

@@ -2,6 +2,7 @@
 Object.defineProperty(exports, "__esModule", {
     value: true
 });
+const _defineProperty = require("@swc/helpers/lib/_define_property.js").default;
 const _tsDecorate = require("@swc/helpers/lib/_ts_decorate.js").default;
 const _tsMetadata = require("@swc/helpers/lib/_ts_metadata.js").default;
 var MyEnum;
@@ -10,6 +11,9 @@ var MyEnum;
     MyEnum["y"] = "yyy";
 })(MyEnum || (MyEnum = {}));
 class Xpto {
+    constructor(){
+        _defineProperty(this, "value", void 0);
+    }
 }
 _tsDecorate([
     Decorator(),

crates/swc/tests/exec/issues-2xxx/2655/1/.swcrc renamed to crates/swc/tests/exec/issues-2xxx/2655/set_public_class_fields/.swcrc

@@ -1,6 +1,7 @@
+import _define_property from "@swc/helpers/src/_define_property.mjs";
 class Foo {
     constructor(){
-        this.static = 5;
-        this.declare = 5;
+        _define_property(this, "static", 5);
+        _define_property(this, "declare", 5);
     }
 }

crates/swc/tests/exec/issues-2xxx/2655/1/exec.ts renamed to crates/swc/tests/exec/issues-2xxx/2655/set_public_class_fields/exec.ts

@@ -2,6 +2,7 @@
 Object.defineProperty(exports, "__esModule", {
     value: true
 });
+const _defineProperty = require("@swc/helpers/lib/_define_property.js").default;
 const _tsDecorate = require("@swc/helpers/lib/_ts_decorate.js").default;
 const _tsMetadata = require("@swc/helpers/lib/_ts_metadata.js").default;
 function MyDecorator(klass) {
@@ -11,6 +12,9 @@ function MyDecorator(klass) {
     };
 }
 class MyClass {
+    constructor(){
+        _defineProperty(this, "prop", void 0);
+    }
 }
 _tsDecorate([
     MyDecorator(MyClass),