From c0ffd70f920f8a7fd86d0ee8c8ce6f74cd45ee89 Mon Sep 17 00:00:00 2001
From: Shu-yu Guo <shu@rfrn.org>
Date: Tue, 2 Feb 2016 14:26:37 -0800
Subject: [PATCH] Bug 1243793 - Fix handling of labels when emitting hoisted
 function definitions. (r=jorendorff)

---
 js/src/frontend/BytecodeEmitter.cpp                  | 12 +++++++-----
 .../block-scoped-functions-deprecated-redecl.js      | 12 ++++++++++++
 2 files changed, 19 insertions(+), 5 deletions(-)

diff --git a/js/src/frontend/BytecodeEmitter.cpp b/js/src/frontend/BytecodeEmitter.cpp
index 201c25054..435b1b4cf 100644
--- a/js/src/frontend/BytecodeEmitter.cpp
+++ b/js/src/frontend/BytecodeEmitter.cpp
@@ -5377,15 +5377,17 @@ BytecodeEmitter::emitHoistedFunctionsInList(ParseNode* list)
     MOZ_ASSERT(list->pn_xflags & PNX_FUNCDEFS);
 
     for (ParseNode* pn = list->pn_head; pn; pn = pn->pn_next) {
+        ParseNode* maybeFun = pn;
+
         if (!sc->strict()) {
-            while (pn->isKind(PNK_LABEL))
-                pn = pn->as<LabeledStatement>().statement();
+            while (maybeFun->isKind(PNK_LABEL))
+                maybeFun = maybeFun->as<LabeledStatement>().statement();
         }
 
-        if (pn->isKind(PNK_ANNEXB_FUNCTION) ||
-            (pn->isKind(PNK_FUNCTION) && pn->functionIsHoisted()))
+        if (maybeFun->isKind(PNK_ANNEXB_FUNCTION) ||
+            (maybeFun->isKind(PNK_FUNCTION) && maybeFun->functionIsHoisted()))
         {
-            if (!emitTree(pn))
+            if (!emitTree(maybeFun))
                 return false;
         }
     }
diff --git a/js/src/tests/ecma_6/LexicalEnvironment/block-scoped-functions-deprecated-redecl.js b/js/src/tests/ecma_6/LexicalEnvironment/block-scoped-functions-deprecated-redecl.js
index 6f023b454..af32be5d3 100644
--- a/js/src/tests/ecma_6/LexicalEnvironment/block-scoped-functions-deprecated-redecl.js
+++ b/js/src/tests/ecma_6/LexicalEnvironment/block-scoped-functions-deprecated-redecl.js
@@ -9,6 +9,18 @@
 // Annex B still works.
 assertEq(f(), 4);
 
+// The same thing with labels.
+{
+  assertEq(f(), 4);
+  function f() { return 3; }
+  assertEq(f(), 4);
+  l: function f() { return 4; }
+  assertEq(f(), 4);
+}
+
+// Annex B still works.
+assertEq(f(), 4);
+
 function test() {
   {
     assertEq(f(), 2);