From d27591806950034d8d3763a13db6f2c201311991 Mon Sep 17 00:00:00 2001
From: Gaming4JC <g4jc@hyperbola.info>
Date: Sun, 9 Jun 2019 01:48:29 -0400
Subject: 1339137 - Don't do Annex B lexical function behavior when redeclaring
 a parameter name in a function with parameter expressions.

---
 js/src/vm/Scope.cpp |  8 ++++++++
 js/src/vm/Scope.h   | 11 +++++++----
 2 files changed, 15 insertions(+), 4 deletions(-)

(limited to 'js/src/vm')

diff --git a/js/src/vm/Scope.cpp b/js/src/vm/Scope.cpp
index a71c03695..0f80d7b69 100644
--- a/js/src/vm/Scope.cpp
+++ b/js/src/vm/Scope.cpp
@@ -669,6 +669,14 @@ FunctionScope::script() const
     return canonicalFunction()->nonLazyScript();
 }
 
+/* static */ bool
+FunctionScope::isSpecialName(ExclusiveContext* cx, JSAtom* name)
+{
+    return name == cx->names().arguments ||
+           name == cx->names().dotThis ||
+           name == cx->names().dotGenerator;
+}
+
 /* static */ Shape*
 FunctionScope::getEmptyEnvironmentShape(ExclusiveContext* cx, bool hasParameterExprs)
 {
diff --git a/js/src/vm/Scope.h b/js/src/vm/Scope.h
index 1d04fd9f6..4a4ae8090 100644
--- a/js/src/vm/Scope.h
+++ b/js/src/vm/Scope.h
@@ -446,10 +446,11 @@ Scope::is<LexicalScope>() const
 }
 
 //
-// Scope corresponding to a function. Holds formal parameter names and, if the
-// function parameters contain no expressions that might possibly be
-// evaluated, the function's var bindings.  For example, in these functions,
-// the FunctionScope will store a/b/c bindings but not d/e/f bindings:
+// Scope corresponding to a function. Holds formal parameter names, special
+// internal names (see FunctionScope::isSpecialName), and, if the function
+// parameters contain no expressions that might possibly be evaluated, the
+// function's var bindings. For example, in these functions, the FunctionScope
+// will store a/b/c bindings but not d/e/f bindings:
 //
 //   function f1(a, b) {
 //     var c;
@@ -562,6 +563,8 @@ class FunctionScope : public Scope
         return data().nonPositionalFormalStart;
     }
 
+    static bool isSpecialName(ExclusiveContext* cx, JSAtom* name);
+
     static Shape* getEmptyEnvironmentShape(ExclusiveContext* cx, bool hasParameterExprs);
 };
 
-- 
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