From 85c2de57e4bcd25b9b61eb9a48e56e8de8c439e7 Mon Sep 17 00:00:00 2001
From: Sebastian McKenzie <sebmck@gmail.com>
Date: Sat, 15 Nov 2014 02:50:05 +1100
Subject: [PATCH] fix for-head duplication testing and replacement - fixes #162

---
 .../transformers/let-scoping.js               | 42 ++++++++++++++-----
 .../let-scoping/exec-block-scoped/exec.js     |  6 +++
 .../exec.js                                   |  0
 .../let-scoping/exec-for-loop-head/exec.js    |  5 +++
 4 files changed, 42 insertions(+), 11 deletions(-)
 create mode 100644 test/fixtures/transformation/let-scoping/exec-block-scoped/exec.js
 rename test/fixtures/transformation/let-scoping/{duplicate-in-upper-scope => exec-duplicate-in-upper-scope}/exec.js (100%)
 create mode 100644 test/fixtures/transformation/let-scoping/exec-for-loop-head/exec.js

diff --git a/lib/6to5/transformation/transformers/let-scoping.js b/lib/6to5/transformation/transformers/let-scoping.js
index b99297a9e6..d31cbd7b84 100644
--- a/lib/6to5/transformation/transformers/let-scoping.js
+++ b/lib/6to5/transformation/transformers/let-scoping.js
@@ -145,11 +145,25 @@ LetScoping.prototype.noClosure = function () {
 
   if (_.isEmpty(replacements)) return;
 
-  traverse(block, function (node, parent) {
+  var replace = function (node, parent) {
     if (!t.isIdentifier(node)) return;
     if (!t.isReferenced(node, parent)) return;
     node.name = replacements[node.name] || node.name;
-  });
+  };
+
+  var traverseReplace = function (node, parent) {
+    replace(node, parent);
+    traverse(node, replace);
+  };
+
+  var forParent = this.forParent;
+  if (forParent) {
+    traverseReplace(forParent.right, forParent);
+    traverseReplace(forParent.test, forParent);
+    traverseReplace(forParent.update, forParent);
+  }
+
+  traverse(block, replace);
 };
 
 /**
@@ -181,10 +195,23 @@ LetScoping.prototype.getInfo = function () {
     keys:        []
   };
 
+  var duplicates = function (id, key) {
+    var has = scope.parentGet(key);
+
+    if (has && has !== id) {
+      // there's a variable with this exact name in an upper scope so we need
+      // to generate a new name
+      opts.duplicates[key] = id.name = file.generateUid(key, scope);
+    }
+  };
+
   _.each(opts.declarators, function (declar) {
     opts.declarators.push(declar);
 
-    var keys = t.getIds(declar);
+    var keys = t.getIds(declar, true);
+    _.each(keys, duplicates);
+    keys = _.keys(keys);
+
     opts.outsideKeys = opts.outsideKeys.concat(keys);
     opts.keys = opts.keys.concat(keys);
   });
@@ -193,14 +220,7 @@ LetScoping.prototype.getInfo = function () {
     if (!isLet(declar)) return;
 
     _.each(t.getIds(declar, true), function (id, key) {
-      var has = scope.parentGet(key);
-
-      if (has && has !== id) {
-        // there's a variable with this exact name in an upper scope so we need
-        // to generate a new name
-        opts.duplicates[key] = id.name = file.generateUid(key, scope);
-      }
-
+      duplicates(id, key);
       opts.keys.push(key);
     });
   });
diff --git a/test/fixtures/transformation/let-scoping/exec-block-scoped/exec.js b/test/fixtures/transformation/let-scoping/exec-block-scoped/exec.js
new file mode 100644
index 0000000000..8b1fd6db2b
--- /dev/null
+++ b/test/fixtures/transformation/let-scoping/exec-block-scoped/exec.js
@@ -0,0 +1,6 @@
+let x = 1;
+{
+  let x = 2;
+  assert.equal(x, 2);
+}
+assert.equal(x, 1);
diff --git a/test/fixtures/transformation/let-scoping/duplicate-in-upper-scope/exec.js b/test/fixtures/transformation/let-scoping/exec-duplicate-in-upper-scope/exec.js
similarity index 100%
rename from test/fixtures/transformation/let-scoping/duplicate-in-upper-scope/exec.js
rename to test/fixtures/transformation/let-scoping/exec-duplicate-in-upper-scope/exec.js
diff --git a/test/fixtures/transformation/let-scoping/exec-for-loop-head/exec.js b/test/fixtures/transformation/let-scoping/exec-for-loop-head/exec.js
new file mode 100644
index 0000000000..59aaae854b
--- /dev/null
+++ b/test/fixtures/transformation/let-scoping/exec-for-loop-head/exec.js
@@ -0,0 +1,5 @@
+assert.equal((function(){
+  let a = 1;
+  for (let a = 0; a < 8; a++) {}
+  return a;
+}()), 1);