diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/gc/bug-880776.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/gc/bug-880776.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,21 @@
+
+gczeal(11);
+var otherGlobal = newGlobal();
+function test(str, arg, result)
+{
+        var fun = new Function('x', str);
+            var code = "(function (x) { " + str + " })";
+                var c = clone(otherGlobal.evaluate(code, {compileAndGo: false}));
+                    assertEq(c.toSource(), eval(code).toSource());
+}
+test('return let (y) x;');
+test('return let (x) "" + x;', 'unicorns', 'undefined');
+test('return let (y = x) (y++, "" + y);', 'unicorns', 'NaN');
+test('return let (y = 1) (y = x, y);');
+test('return let ([] = x) x;');
+test('return let ([, ] = x) x;');
+test('return let ([, , , , ] = x) x;');
+test('return let ([[]] = x) x;');
+test('return let ([[[[[[[[[[[[[]]]]]]]]]]]]] = x) x;');
+test('return let ([[], []] = x) x;');
+test('return let ([[[[]]], [], , [], [[]]] = x) x;');