[es6] Fix default parameters in arrow functions

test/cctest/test-parsing.cc

Index: test/cctest/test-parsing.cc
diff --git a/test/cctest/test-parsing.cc b/test/cctest/test-parsing.cc
index 23a3d2621a8fa78b1ce38d8a8dbbd04f58f6251d..f34315a7f20ccbc24d1e80e414d2f7b989ec4c7d 100644
--- a/test/cctest/test-parsing.cc
+++ b/test/cctest/test-parsing.cc
@@ -1426,6 +1426,7 @@ enum ParserFlag {
   kAllowLazy,
   kAllowNatives,
   kAllowHarmonyArrowFunctions,
+  kAllowHarmonyDefaultParameters,
   kAllowHarmonyRestParameters,
   kAllowHarmonySloppy,
   kAllowHarmonySloppyLet,
@@ -1451,6 +1452,8 @@ void SetParserFlags(i::ParserBase<Traits>* parser,
   parser->set_allow_natives(flags.Contains(kAllowNatives));
   parser->set_allow_harmony_arrow_functions(
       flags.Contains(kAllowHarmonyArrowFunctions));
+  parser->set_allow_harmony_default_parameters(
+      flags.Contains(kAllowHarmonyDefaultParameters));
   parser->set_allow_harmony_rest_parameters(
       flags.Contains(kAllowHarmonyRestParameters));
   parser->set_allow_harmony_spreadcalls(
@@ -3730,10 +3733,27 @@ TEST(NoErrorsArrowFunctions) {
 
     // Arrow has more precedence, this is the same as: foo ? bar : (baz = {})
     "foo ? bar : baz => {}",
+
+    // Arrows with non-simple parameters.
+    "({a}) => {}",
+    "(x = 9) => {}",
+    "(x, y = 9) => {}",
+    "(x = 9, y) => {}",
+    "(x, y = 9, z) => {}",
+    "(x, y = 9, z = 8) => {}",
+    "(...a) => {}",
+    "(x, ...a) => {}",
+    "(x = 9, ...a) => {}",
+    "(x, y = 9, ...a) => {}",
+    "(x, y = 9, {b}, z = 8, ...a) => {}",
+    // TODO(wingo, rossberg): This is not accepted right now.
+    // "({a} = {}) => {}",

[wingo, 2015/08/24 16:01:47]

Perhaps add a pattern for ({a=42})=>{} too?  Unless I am misreading the grammar
of course.   Same thing for array patterns with initializers.  I don't remember
what the state of the implementation is though.

AFAIU default parameters should work now so we probably also need functional
tests, i.e. tests that also invoke the arrow function.

[rossberg, 2015/08/24 17:01:41]

Done.

     NULL
   };
 
-  static const ParserFlag always_flags[] = {kAllowHarmonyArrowFunctions};
+  static const ParserFlag always_flags[] = {
+      kAllowHarmonyArrowFunctions, kAllowHarmonyDefaultParameters,
+      kAllowHarmonyRestParameters, kAllowHarmonyDestructuring};
   RunParserSyncTest(context_data, statement_data, kSuccess, NULL, 0,
                     always_flags, arraysize(always_flags));
 }