Allow eval/arguments in arrow functions

Originally landed in https://codereview.chromium.org/1061983004;
re-landing after re-landing formal parameter parsing refactors.

R=marja@chromium.org
BUG=v8:4020
LOG=N

Review URL: https://codereview.chromium.org/1077153005

Cr-Commit-Position: refs/heads/master@{#27971}

src/messages.js

@@ -166,7 +166,9 @@ var kMessages = {
   for_of_loop_initializer:       ["for-of loop variable declaration may not have an initializer."],
   for_inof_loop_multi_bindings:  ["Invalid left-hand side in ", "%0", " loop: Must have a single binding."],
   bad_getter_arity:              ["Getter must not have any formal parameters."],
-  bad_setter_arity:              ["Setter must have exactly one formal parameter."]
+  bad_setter_arity:              ["Setter must have exactly one formal parameter."],
+  this_formal_parameter:         ["'this' is not a valid formal parameter name"],
+  duplicate_arrow_function_formal_parameter: ["Arrow function may not have duplicate parameter names"]
 };
 
 

src/parser.h

@@ -696,7 +696,6 @@ class ParserTraits {
   static Expression* EmptyExpression() {
     return NULL;
   }
-  static Expression* EmptyArrowParamList() { return NULL; }
   static Literal* EmptyLiteral() {
     return NULL;
   }
@@ -746,11 +745,6 @@ class ParserTraits {
   V8_INLINE Scope* NewScope(Scope* parent_scope, ScopeType scope_type,
                             FunctionKind kind = kNormalFunction);
 
-  // Utility functions
-  int DeclareArrowParametersFromExpression(Expression* expression, Scope* scope,
-                                           FormalParameterErrorLocations* locs,
-                                           bool* ok);
-
   bool DeclareFormalParameter(Scope* scope, const AstRawString* name,
                               bool is_rest) {
     bool is_duplicate = false;
@@ -764,6 +758,14 @@ class ParserTraits {
     return is_duplicate;
   }
 
+  void DeclareArrowFunctionParameters(Scope* scope, Expression* expr,
+                                      const Scanner::Location& params_loc,
+                                      FormalParameterErrorLocations* error_locs,
+                                      bool* ok);
+  void ParseArrowFunctionFormalParameters(
+      Scope* scope, Expression* params, const Scanner::Location& params_loc,
+      FormalParameterErrorLocations* error_locs, bool* is_rest, bool* ok);
+
   // Temporary glue; these functions will move to ParserBase.
   Expression* ParseV8Intrinsic(bool* ok);
   FunctionLiteral* ParseFunctionLiteral(
@@ -1060,8 +1062,6 @@ class Parser : public ParserBase<ParserTraits> {
   ScriptCompiler::CompileOptions compile_options_;
   ParseData* cached_parse_data_;
 
-  bool parsing_lazy_arrow_parameters_;  // for lazily parsed arrow functions.
-
   PendingCompilationErrorHandler pending_error_handler_;
 
   // Other information which will be stored in Parser and moved to Isolate after

test/cctest/test-parsing.cc

@@ -3502,20 +3502,23 @@ TEST(ErrorsArrowFunctions) {
     "(x, (y, z)) => 0",
     "((x, y), z) => 0",
 
-    // Parameter lists are always validated as strict, so those are errors.
-    "eval => {}",
-    "arguments => {}",
-    "yield => {}",
-    "interface => {}",
-    "(eval) => {}",
-    "(arguments) => {}",
-    "(yield) => {}",
-    "(interface) => {}",
-    "(eval, bar) => {}",
-    "(bar, eval) => {}",
-    "(bar, arguments) => {}",
-    "(bar, yield) => {}",
-    "(bar, interface) => {}",
+    // Arrow function formal parameters are parsed as StrictFormalParameters,
+    // which confusingly only implies that there are no duplicates.  Words
+    // reserved in strict mode, and eval or arguments, are indeed valid in
+    // sloppy mode.
+    "eval => { 'use strict'; 0 }",
+    "arguments => { 'use strict'; 0 }",
+    "yield => { 'use strict'; 0 }",
+    "interface => { 'use strict'; 0 }",
+    "(eval) => { 'use strict'; 0 }",
+    "(arguments) => { 'use strict'; 0 }",
+    "(yield) => { 'use strict'; 0 }",
+    "(interface) => { 'use strict'; 0 }",
+    "(eval, bar) => { 'use strict'; 0 }",
+    "(bar, eval) => { 'use strict'; 0 }",
+    "(bar, arguments) => { 'use strict'; 0 }",
+    "(bar, yield) => { 'use strict'; 0 }",
+    "(bar, interface) => { 'use strict'; 0 }",
     // TODO(aperez): Detecting duplicates does not work in PreParser.
     // "(bar, bar) => {}",
 
@@ -3622,6 +3625,66 @@ TEST(NoErrorsArrowFunctions) {
 }
 
 
+TEST(ArrowFunctionsSloppyParameterNames) {
+  const char* strong_context_data[][2] = {
+    {"'use strong'; ", ";"},
+    {"'use strong'; bar ? (", ") : baz;"},
+    {"'use strong'; bar ? baz : (", ");"},
+    {"'use strong'; bar, ", ";"},
+    {"'use strong'; ", ", bar;"},
+    {NULL, NULL}
+  };
+
+  const char* strict_context_data[][2] = {
+    {"'use strict'; ", ";"},
+    {"'use strict'; bar ? (", ") : baz;"},
+    {"'use strict'; bar ? baz : (", ");"},
+    {"'use strict'; bar, ", ";"},
+    {"'use strict'; ", ", bar;"},
+    {NULL, NULL}
+  };
+
+  const char* sloppy_context_data[][2] = {
+    {"", ";"},
+    {"bar ? (", ") : baz;"},
+    {"bar ? baz : (", ");"},
+    {"bar, ", ";"},
+    {"", ", bar;"},
+    {NULL, NULL}
+  };
+
+  const char* statement_data[] = {
+    "eval => {}",
+    "arguments => {}",
+    "yield => {}",
+    "interface => {}",
+    "(eval) => {}",
+    "(arguments) => {}",
+    "(yield) => {}",
+    "(interface) => {}",
+    "(eval, bar) => {}",
+    "(bar, eval) => {}",
+    "(bar, arguments) => {}",
+    "(bar, yield) => {}",
+    "(bar, interface) => {}",
+    "(interface, eval) => {}",
+    "(interface, arguments) => {}",
+    "(eval, interface) => {}",
+    "(arguments, interface) => {}",
+    NULL
+  };
+
+  static const ParserFlag always_flags[] = { kAllowHarmonyArrowFunctions,
+                                             kAllowStrongMode};
+  RunParserSyncTest(strong_context_data, statement_data, kError, NULL, 0,
+                    always_flags, arraysize(always_flags));
+  RunParserSyncTest(strict_context_data, statement_data, kError, NULL, 0,
+                    always_flags, arraysize(always_flags));
+  RunParserSyncTest(sloppy_context_data, statement_data, kSuccess, NULL, 0,
+                    always_flags, arraysize(always_flags));
+}
+
+
 TEST(SuperNoErrors) {
   // Tests that parser and preparser accept 'super' keyword in right places.
   const char* context_data[][2] = {