Merge pull request #3490 from jayphelps/T7324

create new lexical env inside switch statement blocks, fixes #T7324

packages/babel-plugin-transform-es2015-block-scoping/src/index.js

@@ -16,7 +16,7 @@ export default function () {
       VariableDeclaration(path, file) {
         let { node, parent, scope } = path;
         if (!isBlockScoped(node)) return;
-        convertBlockScopedToVar(path, parent, scope, true);
+        convertBlockScopedToVar(path, null, parent, scope, true);
 
         if (node._tdzThis) {
           let nodes = [node];
@@ -51,7 +51,7 @@ export default function () {
         if (replace) path.replaceWith(replace);
       },
 
-      "BlockStatement|Program"(path, file) {
+      "BlockStatement|SwitchStatement|Program"(path, file) {
         if (!t.isLoop(path.parent)) {
           let blockScoping = new BlockScoping(null, path, path.parent, path.scope, file);
           blockScoping.run();
@@ -72,8 +72,10 @@ function isBlockScoped(node) {
   return true;
 }
 
-function convertBlockScopedToVar(path, parent, scope, moveBindingsToParent = false) {
+function convertBlockScopedToVar(path, node, parent, scope, moveBindingsToParent = false) {
-  const { node } = path;
+  if (!node) {
+    node = path.node;
+  }
   // https://github.com/babel/babel/issues/255
   if (!t.isFor(parent)) {
     for (let i = 0; i < node.declarations.length; i++) {
@@ -536,13 +538,30 @@ class BlockScoping {
         if (t.isClassDeclaration(declar) || t.isFunctionDeclaration(declar) || isBlockScoped(declar)) {
           let declarPath = this.blockPath.get("body")[i];
           if (isBlockScoped(declar)) {
-            convertBlockScopedToVar(declarPath, block, this.scope);
+            convertBlockScopedToVar(declarPath, null, block, this.scope);
           }
           declarators = declarators.concat(declar.declarations || declar);
         }
       }
     }
 
+    if (block.cases) {
+      for (let i = 0; i < block.cases.length; i++) {
+        let consequents = block.cases[i].consequent;
+
+        for (let j = 0; j < consequents.length; j++) {
+          let declar = consequents[j];
+          if (t.isClassDeclaration(declar) || t.isFunctionDeclaration(declar) || isBlockScoped(declar)) {
+            let declarPath = this.blockPath.get("cases")[i];
+            if (isBlockScoped(declar)) {
+              convertBlockScopedToVar(declarPath, declar, block, this.scope);
+            }
+            declarators = declarators.concat(declar.declarations || declar);
+          }
+        }
+      }
+    }
+
     //
     for (let i = 0; i < declarators.length; i++) {
       let declar = declarators[i];

packages/babel-plugin-transform-es2015-block-scoping/test/fixtures/general/switch/actual.js

@@ -1,11 +1,27 @@
 let a = true;
 let b = false;
+class e {}
+function f() {}
 
 switch (a) {
   case true:
     let c = 2;
+    let foo = true;
     break;
   case false:
     let d = 3;
+    foo = false;
     break;
 }
+
+switch (true) {
+  case true:
+    let a = false;
+    let b = true;
+    let c = 4;
+    let d = 5;
+
+  case false:
+    class e {}
+    function f() {}
+}

packages/babel-plugin-transform-es2015-block-scoping/test/fixtures/general/switch/expected.js

@@ -1,11 +1,29 @@
 var a = true;
 var b = false;
+class e {}
+function f() {}
 
 switch (a) {
   case true:
     var c = 2;
+    var foo = true;
     break;
   case false:
     var d = 3;
+    foo = false;
     break;
 }
+
+switch (true) {
+  case true:
+    var _a = false;
+    var _b = true;
+    var _c = 4;
+    var _d = 5;
+
+  case false:
+    class _e {}
+
+    var _f = function () {};
+
+}