fix

packages/babel-plugin-transform-for-of/src/index.ts

@@ -18,13 +18,11 @@ function buildLoopBody(
   let block;
   const bodyPath = path.get("body");
   const body = newBody ?? bodyPath.node;
-  const right = path.node.right;
   if (
     t.isBlockStatement(body) &&
-    (Object.keys(path.getBindingIdentifiers()).some(id =>
+    Object.keys(path.getBindingIdentifiers()).some(id =>
       bodyPath.scope.hasOwnBinding(id),
-    ) ||
-      (t.isIdentifier(right) && bodyPath.scope.hasOwnBinding(right.name)))
+    )
   ) {
     block = t.blockStatement([declar, body]);
   } else {
@@ -92,15 +90,14 @@ export default declare((api, options: Options) => {
             return;
           }
           const i = scope.generateUidIdentifier("i");
-          let array: t.Identifier | t.ThisExpression =
-            scope.maybeGenerateMemoised(right, true);
-
-          const inits = [t.variableDeclarator(i, t.numericLiteral(0))];
-          if (array) {
-            inits.push(t.variableDeclarator(array, right));
-          } else {
-            array = right as t.Identifier | t.ThisExpression;
-          }
+          const array: t.Identifier =
+            scope.maybeGenerateMemoised(right, true) ||
+            scope.generateUidIdentifier("arr");
+
+          const inits = [
+            t.variableDeclarator(i, t.numericLiteral(0)),
+            t.variableDeclarator(array, right),
+          ];
 
           const item = t.memberExpression(
             t.cloneNode(array),

packages/babel-plugin-transform-for-of/test/fixtures/assumption-iterableIsArray/for-of-import-amd/output.js

@@ -1,8 +1,8 @@
 define(["foo"], function (_foo) {
   "use strict";
 
-  for (let _i = 0; _i < _foo.array.length; _i++) {
-    const elm = _foo.array[_i];
+  for (let _i = 0, _arr = _foo.array; _i < _arr.length; _i++) {
+    const elm = _arr[_i];
     console.log(elm);
   }
 });

packages/babel-plugin-transform-for-of/test/fixtures/assumption-iterableIsArray/for-of-import-commonjs/output.js

@@ -1,7 +1,7 @@
 "use strict";
 
 var _foo = require("foo");
-for (let _i = 0; _i < _foo.array.length; _i++) {
-  const elm = _foo.array[_i];
+for (let _i = 0, _arr = _foo.array; _i < _arr.length; _i++) {
+  const elm = _arr[_i];
   console.log(elm);
 }

packages/babel-plugin-transform-for-of/test/fixtures/assumption-iterableIsArray/for-of-import-es2015/output.mjs

@@ -1,5 +1,5 @@
 import { array } from "foo";
-for (let _i = 0; _i < array.length; _i++) {
-  const elm = array[_i];
+for (let _i = 0, _arr = array; _i < _arr.length; _i++) {
+  const elm = _arr[_i];
   console.log(elm);
 }

packages/babel-plugin-transform-for-of/test/fixtures/assumption-iterableIsArray/for-of-modify-iterable/input.js

@@ -0,0 +1,3 @@
+for (let o of arr) {
+  arr = null;
+}

packages/babel-plugin-transform-for-of/test/fixtures/assumption-iterableIsArray/for-of-modify-iterable/output.js

@@ -0,0 +1,4 @@
+for (let _i = 0, _arr = arr; _i < _arr.length; _i++) {
+  let o = _arr[_i];
+  arr = null;
+}

packages/babel-plugin-transform-for-of/test/fixtures/assumption-iterableIsArray/for-of-redeclare-iterable/output.js

@@ -1,6 +1,4 @@
 for (let _i = 0, _arr = arr; _i < _arr.length; _i++) {
   let o = _arr[_i];
-  {
-    const arr = o;
-  }
+  const arr = o;
 }

packages/babel-plugin-transform-for-of/test/fixtures/assumption-iterableIsArray/for-of-static-declaration/output.js

@@ -1,5 +1,5 @@
 const array = [];
-for (let _i = 0; _i < array.length; _i++) {
-  const elm = array[_i];
+for (let _i = 0, _arr = array; _i < _arr.length; _i++) {
+  const elm = _arr[_i];
   console.log(elm);
 }

packages/babel-plugin-transform-for-of/test/fixtures/assumption-iterableIsArray/for-of-static/output.js

@@ -1,6 +1,6 @@
 const array = [];
 let elm;
-for (let _i = 0; _i < array.length; _i++) {
-  elm = array[_i];
+for (let _i = 0, _arr = array; _i < _arr.length; _i++) {
+  elm = _arr[_i];
   console.log(elm);
 }

packages/babel-plugin-transform-for-of/test/fixtures/for-of-as-array/for-of-import-amd/output.js

@@ -1,8 +1,8 @@
 define(["foo"], function (_foo) {
   "use strict";
 
-  for (let _i = 0; _i < _foo.array.length; _i++) {
-    const elm = _foo.array[_i];
+  for (let _i = 0, _arr = _foo.array; _i < _arr.length; _i++) {
+    const elm = _arr[_i];
     console.log(elm);
   }
 });

packages/babel-plugin-transform-for-of/test/fixtures/for-of-as-array/for-of-import-commonjs/output.js

@@ -1,7 +1,7 @@
 "use strict";
 
 var _foo = require("foo");
-for (let _i = 0; _i < _foo.array.length; _i++) {
-  const elm = _foo.array[_i];
+for (let _i = 0, _arr = _foo.array; _i < _arr.length; _i++) {
+  const elm = _arr[_i];
   console.log(elm);
 }

packages/babel-plugin-transform-for-of/test/fixtures/for-of-as-array/for-of-import-es2015/output.mjs

@@ -1,5 +1,5 @@
 import { array } from "foo";
-for (let _i = 0; _i < array.length; _i++) {
-  const elm = array[_i];
+for (let _i = 0, _arr = array; _i < _arr.length; _i++) {
+  const elm = _arr[_i];
   console.log(elm);
 }

packages/babel-plugin-transform-for-of/test/fixtures/for-of-as-array/for-of-redeclare-iterable/output.js

@@ -1,6 +1,4 @@
 for (let _i = 0, _arr = arr; _i < _arr.length; _i++) {
   let o = _arr[_i];
-  {
-    const arr = o;
-  }
+  const arr = o;
 }

packages/babel-plugin-transform-for-of/test/fixtures/for-of-as-array/for-of-static-declaration/output.js

@@ -1,5 +1,5 @@
 const array = [];
-for (let _i = 0; _i < array.length; _i++) {
-  const elm = array[_i];
+for (let _i = 0, _arr = array; _i < _arr.length; _i++) {
+  const elm = _arr[_i];
   console.log(elm);
 }

packages/babel-plugin-transform-for-of/test/fixtures/for-of-as-array/for-of-static/output.js

@@ -1,6 +1,6 @@
 const array = [];
 let elm;
-for (let _i = 0; _i < array.length; _i++) {
-  elm = array[_i];
+for (let _i = 0, _arr = array; _i < _arr.length; _i++) {
+  elm = _arr[_i];
   console.log(elm);
 }

packages/babel-plugin-transform-for-of/test/fixtures/regression/redeclare-array-8913/output.js

@@ -1,8 +1,6 @@
 function f(...t) {
   for (var _i = 0, _t = t; _i < _t.length; _i++) {
     let o = _t[_i];
-    {
-      const t = o;
-    }
+    const t = o;
   }
 }

packages/babel-preset-env/test/fixtures/plugins-integration/for-of-array-block-scoping-2/exec.js

@@ -0,0 +1,10 @@
+function x(e){
+  const r = [];
+  for (const s of e) {
+    e = null;
+    r.push(s);
+  }
+  return r;
+}
+
+expect(x([1, 2, 3])).toEqual([1, 2, 3]);

packages/babel-preset-env/test/fixtures/plugins-integration/for-of-array-block-scoping-2/input.js

@@ -0,0 +1,10 @@
+function x(e){
+  const r = [];
+  for (const s of e) {
+    e = null;
+    r.push(s);
+  }
+  return r;
+}
+
+expect(x([1, 2, 3])).toEqual([1, 2, 3]);

packages/babel-preset-env/test/fixtures/plugins-integration/for-of-array-block-scoping-2/options.json

@@ -0,0 +1,7 @@
+{
+  "assumptions": {
+    "iterableIsArray": true
+  },
+  "targets": "node 4.0",
+  "presets": ["env"]
+}

packages/babel-preset-env/test/fixtures/plugins-integration/for-of-array-block-scoping-2/output.js

@@ -0,0 +1,10 @@
+function x(e) {
+  var r = [];
+  for (var _i2 = 0, _e2 = e; _i2 < _e2.length; _i2++) {
+    var s = _e2[_i2];
+    e = null;
+    r.push(s);
+  }
+  return r;
+}
+expect(x([1, 2, 3])).toEqual([1, 2, 3]);

packages/babel-preset-env/test/fixtures/plugins-integration/for-of-array-block-scoping/output.js

@@ -1,11 +1,9 @@
 function x(e) {
   var r = [];
-  for (var _i2 = 0; _i2 < e.length; _i2++) {
-    var s = e[_i2];
-    {
-      var _e = s;
-      r.push(_e);
-    }
+  for (var _i2 = 0, _arr2 = e; _i2 < _arr2.length; _i2++) {
+    var s = _arr2[_i2];
+    var _e = s;
+    r.push(_e);
   }
   return r;
 }