Skip discriminant when renaming starting from SwitchStatement (#12530)

packages/babel-plugin-transform-block-scoping/test/fixtures/general/rename-inside-switch/input.js

@@ -0,0 +1,20 @@
+window.test = () => {
+    const e = "TEST";
+    switch (e) {
+        case "TEST":
+            const e = [];
+            e.push('111');
+            alert(e);
+            break;
+        default: alert('666'); break;
+    }
+};
+
+window.test = () => {
+    const e = "TEST";
+    switch (e) {
+        case "TEST":
+            const e = [];
+            switch(e) {}
+    }
+};

packages/babel-plugin-transform-block-scoping/test/fixtures/general/rename-inside-switch/output.js

@@ -0,0 +1,29 @@
+window.test = function () {
+  var e = "TEST";
+
+  switch (e) {
+    case "TEST":
+      var _e = [];
+
+      _e.push('111');
+
+      alert(_e);
+      break;
+
+    default:
+      alert('666');
+      break;
+  }
+};
+
+window.test = function () {
+  var e = "TEST";
+
+  switch (e) {
+    case "TEST":
+      var _e2 = [];
+
+      switch (_e2) {}
+
+  }
+};

packages/babel-traverse/src/scope/lib/renamer.js

@@ -119,7 +119,15 @@ export default class Renamer {
       }
     }
 
-    scope.traverse(block || scope.block, renameVisitor, this);
+    const blockToTraverse = block || scope.block;
+    if (blockToTraverse?.type === "SwitchStatement") {
+      // discriminant is not part of current scope, should be skipped.
+      blockToTraverse.cases.forEach(c => {
+        scope.traverse(c, renameVisitor, this);
+      });
+    } else {
+      scope.traverse(blockToTraverse, renameVisitor, this);
+    }
 
     if (!block) {
       scope.removeOwnBinding(oldName);