fix duplicate let scoping in functions - fixes #166

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.

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();

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");