babel · JLHwung · Nov 7, 2025 · Oct 22, 2025
diff --git a/packages/babel-plugin-transform-regenerator/src/regenerator/hoist.ts b/packages/babel-plugin-transform-regenerator/src/regenerator/hoist.ts
@@ -13,7 +13,7 @@ export function hoist(
   const vars: Record<string, t.Identifier> = { __proto__: null };
 
   function varDeclToExpr(
-    { node: vdec, scope }: NodePath,
+    { node: vdec }: NodePath,
     includeIdentifiers: boolean,
   ) {
     t.assertVariableDeclaration(vdec);
@@ -27,10 +27,6 @@ export function hoist(
       // have the same 'loc' value, since that can make sourcemaps and retainLines behave poorly.
       vars[dec.id.name] = t.identifier(dec.id.name);
 
-      // Remove the binding, to avoid "duplicate declaration" errors when it will
-      // be injected again.
-      scope.removeBinding(dec.id.name);
-
       if (dec.init) {
         exprs.push(t.assignmentExpression("=", dec.id, dec.init));
       } else if (includeIdentifiers) {
@@ -52,6 +48,12 @@ export function hoist(
         if (expr === null) {
           path.remove();
         } else {
+          for (const name of Object.keys(vars)) {
+            // Remove the binding, to avoid "duplicate declaration" errors when it will
+            // be injected again.
+            path.scope.removeBinding(name);
+          }
+
           // We don't need to traverse this expression any further because
           // there can't be any new declarations inside an expression.
           path.replaceWith(t.expressionStatement(expr));
@@ -113,11 +115,11 @@ export function hoist(
         // replace the declaration with the equivalent assignment form
         // without worrying about hoisting it.
         path.replaceWith(assignment);
-      }
 
-      // Remove the binding, to avoid "duplicate declaration" errors when it will
-      // be injected again.
-      path.scope.removeBinding(node.id.name);
+        // Remove the binding, to avoid "duplicate declaration" errors when it will
+        // be injected again.
+        path.scope.removeBinding(node.id.name);
+      }
 
       // Don't hoist variables out of inner functions.
       path.skip();

diff --git a/packages/babel-plugin-transform-regenerator/test/fixtures/scope/17543-2/input.mjs b/packages/babel-plugin-transform-regenerator/test/fixtures/scope/17543-2/input.mjs
@@ -0,0 +1,7 @@
+import {useLayoutEffect as n} from "react";
+
+function Ki(i, n) {
+  return i(async () => {
+    var n;
+  }, n); // This n is the one from the Ki function, not from the import statement
+}
diff --git a/packages/babel-plugin-transform-regenerator/test/fixtures/scope/17543-2/options.json b/packages/babel-plugin-transform-regenerator/test/fixtures/scope/17543-2/options.json
@@ -0,0 +1,3 @@
+{
+  "plugins": ["transform-modules-commonjs", "transform-regenerator"]
+}
diff --git a/packages/babel-plugin-transform-regenerator/test/fixtures/scope/17543-2/output.js b/packages/babel-plugin-transform-regenerator/test/fixtures/scope/17543-2/output.js
@@ -0,0 +1,14 @@
+"use strict";
+
+var _react = require("react");
+function Ki(i, n) {
+  return i(() => {
+    var n;
+    return babelHelpers.regeneratorAsync(function (_context) {
+      while (1) switch (_context.n) {
+        case 0:
+          return _context.a(2);
+      }
+    }, null, null, null, Promise);
+  }, n); // This n is the one from the Ki function, not from the import statement
+}
diff --git a/packages/babel-plugin-transform-regenerator/test/fixtures/scope/17543/input.mjs b/packages/babel-plugin-transform-regenerator/test/fixtures/scope/17543/input.mjs
@@ -0,0 +1,7 @@
+import {useLayoutEffect as n} from "react";
+
+function Ki(i, n) {
+  return i(async () => {
+    function n() {}
+  }, n); // This n is the one from the Ki function, not from the import statement
+}
diff --git a/packages/babel-plugin-transform-regenerator/test/fixtures/scope/17543/options.json b/packages/babel-plugin-transform-regenerator/test/fixtures/scope/17543/options.json
@@ -0,0 +1,3 @@
+{
+  "plugins": ["transform-modules-commonjs", "transform-regenerator"]
+}
diff --git a/packages/babel-plugin-transform-regenerator/test/fixtures/scope/17543/output.js b/packages/babel-plugin-transform-regenerator/test/fixtures/scope/17543/output.js
@@ -0,0 +1,16 @@
+"use strict";
+
+var _react = require("react");
+function Ki(i, n) {
+  return i(() => {
+    var n;
+    return babelHelpers.regeneratorAsync(function (_context) {
+      while (1) switch (_context.n) {
+        case 0:
+          n = function _n() {};
+        case 1:
+          return _context.a(2);
+      }
+    }, null, null, null, Promise);
+  }, n); // This n is the one from the Ki function, not from the import statement
+}