From 7a261a1db16adf2104cacb4e16f81a0e2133e65c Mon Sep 17 00:00:00 2001
From: Sebastian McKenzie <sebmck@gmail.com>
Date: Sat, 15 Nov 2014 09:47:48 +1100
Subject: [PATCH] fix duplicate let scoping in functions - fixes #166

---
 CHANGELOG.md                                           |  4 ++++
 lib/6to5/transformation/transformers/let-scoping.js    |  5 +++--
 .../let-scoping/exec-duplicate-function-scope/exec.js  | 10 ++++++++++
 3 files changed, 17 insertions(+), 2 deletions(-)
 create mode 100644 test/fixtures/transformation/let-scoping/exec-duplicate-function-scope/exec.js

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 23975edb7a4a..1ebc01b6104a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+# 1.12.4
+
+ * Fix duplicate let scoping in functions.
+
 # 1.12.13
 
  * Support duplicate constants within different block scopes.
diff --git a/lib/6to5/transformation/transformers/let-scoping.js b/lib/6to5/transformation/transformers/let-scoping.js
index d31cbd7b8476..9ccd879620ef 100644
--- a/lib/6to5/transformation/transformers/let-scoping.js
+++ b/lib/6to5/transformation/transformers/let-scoping.js
@@ -74,7 +74,6 @@ function LetScoping(forParent, block, parent, file, scope) {
 
   this.letReferences = {};
   this.body          = [];
-  this.info          = this.getInfo();
 }
 
 /**
@@ -87,8 +86,10 @@ LetScoping.prototype.run = function () {
   if (block._letDone) return;
   block._letDone = true;
 
+  this.info = this.getInfo();
+
   // this is a block within a `Function` so we can safely leave it be
-  if (t.isFunction(this.parent)) return;
+  if (t.isFunction(this.parent)) return this.noClosure();
 
   // this block has no let references so let's clean up
   if (!this.info.keys.length) return this.noClosure();
diff --git a/test/fixtures/transformation/let-scoping/exec-duplicate-function-scope/exec.js b/test/fixtures/transformation/let-scoping/exec-duplicate-function-scope/exec.js
new file mode 100644
index 000000000000..68cb396aebf6
--- /dev/null
+++ b/test/fixtures/transformation/let-scoping/exec-duplicate-function-scope/exec.js
@@ -0,0 +1,10 @@
+function test () {
+  let value = "outer";
+
+  return (function () {
+    let value = "inner";
+    return value;
+  })();
+}
+
+assert(test(), "inner");