Improve error message for duplicate parameters

src/messages.h

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // The infrastructure used for (localized) message reporting in V8.
 //
 // Note: there's a big unresolved issue about ownership of the data
 // structures used by this framework.
 
 #ifndef V8_MESSAGES_H_
@@ skipping 279 matching lines @@
   T(TypedArraySetSourceTooLarge, "Source is too large")                        \
   T(UnsupportedTimeZone, "Unsupported time zone specified %")                  \
   T(ValueOutOfRange, "Value % out of range for % options property %")          \
   /* SyntaxError */                                                            \
   T(BadGetterArity, "Getter must not have any formal parameters.")             \
   T(BadSetterArity, "Setter must have exactly one formal parameter.")          \
   T(ConstructorIsAccessor, "Class constructor may not be an accessor")         \
   T(ConstructorIsGenerator, "Class constructor may not be a generator")        \
   T(DerivedConstructorReturn,                                                  \
     "Derived constructors may only return object or undefined")                \
-  T(DuplicateArrawFunFormalParam,                                              \
-    "Arrow function may not have duplicate parameter names")                   \
   T(DuplicateConstructor, "A class may only have one constructor")             \
   T(DuplicateExport, "Duplicate export of '%'")                                \
   T(DuplicateProto,                                                            \
     "Duplicate __proto__ fields are not allowed in object literals")           \
   T(ForInLoopInitializer,                                                      \
     "for-in loop variable declaration may not have an initializer.")           \
   T(ForInOfLoopMultiBindings,                                                  \
     "Invalid left-hand side in % loop: Must have a single binding.")           \
   T(ForOfLoopInitializer,                                                      \
     "for-of loop variable declaration may not have an initializer.")           \
@@ skipping 16 matching lines @@
     "Expected () to start arrow function, but got '%' instead of '=>'")        \
   T(ModuleExportUndefined, "Export '%' is not defined in module")              \
   T(MultipleDefaultsInSwitch,                                                  \
     "More than one default clause in switch statement")                        \
   T(NewlineAfterThrow, "Illegal newline after throw")                          \
   T(NoCatchOrFinally, "Missing catch or finally after try")                    \
   T(NotIsvar, "builtin %%IS_VAR: not a variable")                              \
   T(ParamAfterRest, "Rest parameter must be last formal parameter")            \
   T(BadSetterRestParameter,                                                    \
     "Setter function argument must not be a rest parameter")                   \
+  T(ParamDupe, "Duplicate parameter name not allowed in this context")         \
   T(ParenthesisInArgString, "Function arg string contains parenthesis")        \
   T(SingleFunctionLiteral, "Single function literal required")                 \
   T(SloppyLexical,                                                             \
     "Block-scoped declarations (let, const, function, class) not yet "         \
     "supported outside strict mode")                                           \
   T(StrictDelete, "Delete of an unqualified identifier in strict mode.")       \
   T(StrictEvalArguments, "Unexpected eval or arguments in strict mode")        \
   T(StrictFunction,                                                            \
     "In strict mode code, functions can only be declared at top level or "     \
     "immediately within another function.")                                    \
   T(StrictOctalLiteral, "Octal literals are not allowed in strict mode.")      \
-  T(StrictParamDupe,                                                           \
-    "Strict mode function may not have duplicate parameter names")             \
   T(StrictWith, "Strict mode code may not include a with statement")           \
   T(StrongArguments,                                                           \
     "In strong mode, 'arguments' is deprecated, use '...args' instead")        \
   T(StrongConstructorReturnMisplaced,                                          \
     "In strong mode, returning from a constructor before its super "           \
     "constructor invocation or all assignments to 'this' is deprecated")       \
   T(StrongConstructorReturnValue,                                              \
     "In strong mode, returning a value from a constructor is deprecated")      \
   T(StrongConstructorSuper,                                                    \
     "In strong mode, 'super' can only be used to invoke the super "            \
@@ skipping 94 matching lines @@
 
   static void DefaultMessageReport(Isolate* isolate, const MessageLocation* loc,
                                    Handle<Object> message_obj);
   static Handle<String> GetMessage(Isolate* isolate, Handle<Object> data);
   static base::SmartArrayPointer<char> GetLocalizedMessage(Isolate* isolate,
                                                            Handle<Object> data);
 };
 } }  // namespace v8::internal
 
 #endif  // V8_MESSAGES_H_