fix(es/codegen): Emit decorators on class methods (#4103)

Cargo.lock

@@ -3039,6 +3039,7 @@ dependencies = [
  "swc_ecma_parser",
  "swc_ecma_transforms_base",
  "swc_ecma_transforms_optimization",
+ "swc_ecma_transforms_proposal",
  "swc_ecma_transforms_react",
  "swc_ecma_transforms_typescript",
  "swc_ecma_utils",

crates/swc_bundler/Cargo.toml

@@ -65,6 +65,7 @@ swc_ecma_loader = { version = "0.29.0", path = "../swc_ecma_loader", features =
   "cache",
 ] }
 swc_ecma_minifier = { version = "0.94.0", path = "../swc_ecma_minifier" }
+swc_ecma_transforms_proposal = { version = "0.91.0", path = "../swc_ecma_transforms_proposal" }
 swc_ecma_transforms_react = { version = "0.98.0", path = "../swc_ecma_transforms_react" }
 swc_ecma_transforms_typescript = { version = "0.101.0", path = "../swc_ecma_transforms_typescript" }
 swc_node_base = { version = "0.5.0", path = "../swc_node_base" }

crates/swc_bundler/tests/common/mod.rs

@@ -18,7 +18,11 @@ use swc_common::{
 };
 use swc_ecma_ast::EsVersion;
 use swc_ecma_parser::{parse_file_as_module, Syntax, TsConfig};
-use swc_ecma_transforms_base::resolver::resolver_with_mark;
+use swc_ecma_transforms_base::{
+    helpers::{inject_helpers, Helpers, HELPERS},
+    resolver::resolver_with_mark,
+};
+use swc_ecma_transforms_proposal::decorators;
 use swc_ecma_transforms_react::react;
 use swc_ecma_transforms_typescript::strip;
 use swc_ecma_visit::FoldWith;
@@ -128,15 +132,22 @@ impl Load for Loader {
         });
 
         let mark = Mark::fresh(Mark::root());
-        let module = module
-            .fold_with(&mut resolver_with_mark(mark))
-            .fold_with(&mut strip(mark))
-            .fold_with(&mut react::<SingleThreadedComments>(
-                self.cm.clone(),
-                None,
-                Default::default(),
-                top_level_mark,
-            ));
+        let module = HELPERS.set(&Helpers::new(false), || {
+            module
+                .fold_with(&mut resolver_with_mark(mark))
+                .fold_with(&mut decorators(decorators::Config {
+                    legacy: true,
+                    emit_metadata: Default::default(),
+                }))
+                .fold_with(&mut strip(mark))
+                .fold_with(&mut react::<SingleThreadedComments>(
+                    self.cm.clone(),
+                    None,
+                    Default::default(),
+                    top_level_mark,
+                ))
+                .fold_with(&mut inject_helpers())
+        });
 
         Ok(ModuleData {
             fm,

crates/swc_ecma_codegen/src/lib.rs

@@ -1223,6 +1223,10 @@ where
 
         srcmap!(n, true);
 
+        for d in &n.function.decorators {
+            emit!(d);
+        }
+
         self.emit_accessibility(n.accessibility)?;
 
         if n.is_static {