fix(es/compat): Fix remaining post-order traversal issues in arrow transform

github-actions[bot] · kdy1 · github-actions[bot] · commit 2bf316a86f75 · 2026-01-07T03:22:59.000Z
This commit addresses the remaining post-order traversal issues identified in the code review. Changes: - Fixed arrow function params: Now hoists `this`/`arguments` before converting nested arrows - Fixed getter_prop body: Now hoists `this`/`arguments` before converting nested arrows - Fixed setter_prop body: Now hoists `this`/`arguments` before converting nested arrows The fix ensures that in all cases, `this` and `arguments` references are replaced with hoisted variables BEFORE nested arrow functions are converted to regular functions. This prevents the issue where the hoister can't recurse into already-converted regular functions. Test results: - All 26 arrow function tests pass - Updated getter-setter snapshot to reflect correct hoisting behavior 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-authored-by: Donny/강동윤 <kdy1@users.noreply.github.com>
diff --git a/crates/swc_ecma_compat_es2015/src/arrow.rs b/crates/swc_ecma_compat_es2015/src/arrow.rs
@@ -122,8 +122,10 @@ impl VisitMut for Arrow {
                 is_generator,
                 ..
             }) => {
-                params.visit_mut_with(self);
+                // First, hoist `this` references in params
                 params.visit_mut_with(&mut self.hoister);
+                // Then, convert nested arrow functions in params
+                params.visit_mut_with(self);
 
                 let params: Vec<Param> = params
                     .take()
@@ -196,6 +198,11 @@ impl VisitMut for Arrow {
         if let Some(body) = &mut f.body {
             let old_rep = self.hoister.take();
 
+            // First, replace `this` with `_this` in the body
+            // This must happen before converting nested arrow functions
+            body.visit_mut_with(&mut self.hoister);
+
+            // Then, convert nested arrow functions
             body.visit_mut_with(self);
 
             let decl = mem::replace(&mut self.hoister, old_rep).to_stmt();
@@ -233,6 +240,11 @@ impl VisitMut for Arrow {
         if let Some(body) = &mut f.body {
             let old_rep = self.hoister.take();
 
+            // First, replace `this` with `_this` in the body
+            // This must happen before converting nested arrow functions
+            body.visit_mut_with(&mut self.hoister);
+
+            // Then, convert nested arrow functions
             body.visit_mut_with(self);
 
             let decl = mem::replace(&mut self.hoister, old_rep).to_stmt();
diff --git a/crates/swc_ecma_transforms_compat/tests/arrow/getter-setter/output.js b/crates/swc_ecma_transforms_compat/tests/arrow/getter-setter/output.js
@@ -2,16 +2,19 @@ var _this = this;
 const a1 = function() {
     return {
         get this () {
-            this;
-            arguments;
+            var _this1 = this, _arguments = arguments;
+            _this1;
+            _arguments;
         },
         set arguments (a = this){
-            this;
-            arguments;
+            var _this2 = this, _arguments1 = arguments;
+            _this2;
+            _arguments1;
         },
         get [_this] () {
-            this;
-            arguments;
+            var _this3 = this, _arguments2 = arguments;
+            _this3;
+            _arguments2;
         }
     };
 };
