Updated to Chrome 45 (2454) moved from SVN to git.

bindings/scripts/v8_methods.py

 # Copyright (C) 2013 Google Inc. All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 # notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
 # copyright notice, this list of conditions and the following disclaimer
@@ skipping 21 matching lines @@
 Extends IdlTypeBase and IdlUnionType with property |union_arguments|.
 
 Design doc: http://www.chromium.org/developers/design-documents/idl-compiler
 """
 
 from idl_definitions import IdlArgument, IdlOperation
 from idl_types import IdlTypeBase, IdlUnionType, inherits_interface
 from v8_globals import includes
 import v8_types
 import v8_utilities
-from v8_utilities import has_extended_attribute_value
+from v8_utilities import (has_extended_attribute_value, is_unforgeable,
+                          is_legacy_interface_type_checking)
 
 
 # Methods with any of these require custom method registration code in the
 # interface's configure*Template() function.
 CUSTOM_REGISTRATION_EXTENDED_ATTRIBUTES = frozenset([
     'DoNotCheckSecurity',
     'DoNotCheckSignature',
     'NotEnumerable',
     'Unforgeable',
 ])
 
 
 def use_local_result(method):
     extended_attributes = method.extended_attributes
     idl_type = method.idl_type
     return (has_extended_attribute_value(method, 'CallWith', 'ScriptState') or
             'ImplementedInPrivateScript' in extended_attributes or
             'RaisesException' in extended_attributes or
             idl_type.is_union_type or
             idl_type.is_explicit_nullable)
 
 
-def method_context(interface, method):
+def method_context(interface, method, is_visible=True):
     arguments = method.arguments
     extended_attributes = method.extended_attributes
     idl_type = method.idl_type
     is_static = method.is_static
     name = method.name
 
-    idl_type.add_includes_for_type()
+    if is_visible:
+        idl_type.add_includes_for_type(extended_attributes)
+
     this_cpp_value = cpp_value(interface, method, len(arguments))
 
     def function_template():
         if is_static:
             return 'functionTemplate'
-        if 'Unforgeable' in extended_attributes:
+        if is_unforgeable(interface, method):
             return 'instanceTemplate'
         return 'prototypeTemplate'
 
     is_implemented_in_private_script = 'ImplementedInPrivateScript' in extended_attributes
     if is_implemented_in_private_script:
         includes.add('bindings/core/v8/PrivateScriptRunner.h')
         includes.add('core/frame/LocalFrame.h')
         includes.add('platform/ScriptForbiddenScope.h')
 
     # [OnlyExposedToPrivateScript]
     is_only_exposed_to_private_script = 'OnlyExposedToPrivateScript' in extended_attributes
 
     is_call_with_script_arguments = has_extended_attribute_value(method, 'CallWith', 'ScriptArguments')
     if is_call_with_script_arguments:
         includes.update(['bindings/core/v8/ScriptCallStackFactory.h',
                          'core/inspector/ScriptArguments.h'])
     is_call_with_script_state = has_extended_attribute_value(method, 'CallWith', 'ScriptState')
-    if is_call_with_script_state:
-        includes.add('bindings/core/v8/V8ScriptState.h')
+    is_call_with_this_value = has_extended_attribute_value(method, 'CallWith', 'ThisValue')
+    if is_call_with_script_state or is_call_with_this_value:
+        includes.add('bindings/core/v8/ScriptState.h')
     is_check_security_for_node = 'CheckSecurity' in extended_attributes
     if is_check_security_for_node:
-        includes.add('bindings/common/BindingSecurity.h')
+        includes.add('bindings/core/v8/BindingSecurity.h')
     is_custom_element_callbacks = 'CustomElementCallbacks' in extended_attributes
     if is_custom_element_callbacks:
         includes.add('core/dom/custom/CustomElementProcessingStack.h')
 
     is_do_not_check_security = 'DoNotCheckSecurity' in extended_attributes
 
     is_check_security_for_frame = (
         has_extended_attribute_value(interface, 'CheckSecurity', 'Frame') and
         not is_do_not_check_security)
 
     is_check_security_for_window = (
         has_extended_attribute_value(interface, 'CheckSecurity', 'Window') and
         not is_do_not_check_security)
 
     is_raises_exception = 'RaisesException' in extended_attributes
+    is_custom_call_prologue = has_extended_attribute_value(method, 'Custom', 'CallPrologue')
+    is_custom_call_epilogue = has_extended_attribute_value(method, 'Custom', 'CallEpilogue')
+    is_post_message = 'PostMessage' in extended_attributes
+    if is_post_message:
+        includes.add('bindings/core/v8/SerializedScriptValueFactory.h')
+        includes.add('core/dom/DOMArrayBuffer.h')
+        includes.add('core/dom/MessagePort.h')
+
+    if 'LenientThis' in extended_attributes:
+        raise Exception('[LenientThis] is not supported for operations.')
 
     return {
         'activity_logging_world_list': v8_utilities.activity_logging_world_list(method),  # [ActivityLogging]
-        'arguments': [argument_context(interface, method, argument, index)
+        'arguments': [argument_context(interface, method, argument, index, is_visible=is_visible)
                       for index, argument in enumerate(arguments)],
         'argument_declarations_for_private_script':
             argument_declarations_for_private_script(interface, method),
         'conditional_string': v8_utilities.conditional_string(method),
         'cpp_type': (v8_types.cpp_template_type('Nullable', idl_type.cpp_type)
                      if idl_type.is_explicit_nullable else idl_type.cpp_type),
         'cpp_value': this_cpp_value,
         'cpp_type_initializer': idl_type.cpp_type_initializer,
         'custom_registration_extended_attributes':
             CUSTOM_REGISTRATION_EXTENDED_ATTRIBUTES.intersection(
                 extended_attributes.iterkeys()),
         'deprecate_as': v8_utilities.deprecate_as(method),  # [DeprecateAs]
         'exposed_test': v8_utilities.exposed(method, interface),  # [Exposed]
         'function_template': function_template(),
-        'has_custom_registration': is_static or
+        'has_custom_registration':
+            is_static or
+            is_unforgeable(interface, method) or
             v8_utilities.has_extended_attribute(
                 method, CUSTOM_REGISTRATION_EXTENDED_ATTRIBUTES),
         'has_exception_state':
             is_raises_exception or
             is_check_security_for_frame or
             is_check_security_for_window or
             any(argument for argument in arguments
                 if (argument.idl_type.name == 'SerializedScriptValue' or
                     argument_conversion_needs_exception_state(method, argument))),
         'idl_type': idl_type.base_type,
         'is_call_with_execution_context': has_extended_attribute_value(method, 'CallWith', 'ExecutionContext'),
         'is_call_with_script_arguments': is_call_with_script_arguments,
         'is_call_with_script_state': is_call_with_script_state,
+        'is_call_with_this_value': is_call_with_this_value,
         'is_check_security_for_frame': is_check_security_for_frame,
         'is_check_security_for_node': is_check_security_for_node,
         'is_check_security_for_window': is_check_security_for_window,
-        'is_custom': 'Custom' in extended_attributes,
+        'is_custom': 'Custom' in extended_attributes and
+            not (is_custom_call_prologue or is_custom_call_epilogue),
+        'is_custom_call_prologue': is_custom_call_prologue,
+        'is_custom_call_epilogue': is_custom_call_epilogue,
         'is_custom_element_callbacks': is_custom_element_callbacks,
         'is_do_not_check_security': is_do_not_check_security,
         'is_do_not_check_signature': 'DoNotCheckSignature' in extended_attributes,
         'is_explicit_nullable': idl_type.is_explicit_nullable,
         'is_implemented_in_private_script': is_implemented_in_private_script,
         'is_partial_interface_member':
             'PartialInterfaceImplementedAs' in extended_attributes,
         'is_per_world_bindings': 'PerWorldBindings' in extended_attributes,
+        'is_post_message': is_post_message,
         'is_raises_exception': is_raises_exception,
-        'is_read_only': 'Unforgeable' in extended_attributes,
+        'is_read_only': is_unforgeable(interface, method),
         'is_static': is_static,
         'is_variadic': arguments and arguments[-1].is_variadic,
-        'measure_as': v8_utilities.measure_as(method),  # [MeasureAs]
+        'measure_as': v8_utilities.measure_as(method, interface),  # [MeasureAs]
         'name': name,
         'number_of_arguments': len(arguments),
         'number_of_required_arguments': len([
             argument for argument in arguments
             if not (argument.is_optional or argument.is_variadic)]),
         'number_of_required_or_variadic_arguments': len([
             argument for argument in arguments
             if not argument.is_optional]),
+        'on_instance': v8_utilities.on_instance(interface, method),
+        'on_interface': v8_utilities.on_interface(interface, method),
+        'on_prototype': v8_utilities.on_prototype(interface, method),
         'only_exposed_to_private_script': is_only_exposed_to_private_script,
-        'per_context_enabled_function': v8_utilities.per_context_enabled_function_name(method),  # [PerContextEnabled]
         'private_script_v8_value_to_local_cpp_value': idl_type.v8_value_to_local_cpp_value(
-            extended_attributes, 'v8Value', 'cppValue', isolate='scriptState->isolate()', used_in_private_script=True),
-        'property_attributes': property_attributes(method),
+            extended_attributes, 'v8Value', 'cppValue', isolate='scriptState->isolate()', bailout_return_value='false'),
+        'property_attributes': property_attributes(interface, method),
+        'returns_promise': method.returns_promise,
         'runtime_enabled_function': v8_utilities.runtime_enabled_function_name(method),  # [RuntimeEnabled]
         'should_be_exposed_to_script': not (is_implemented_in_private_script and is_only_exposed_to_private_script),
         'signature': 'v8::Local<v8::Signature>()' if is_static or 'DoNotCheckSignature' in extended_attributes else 'defaultSignature',
-        'union_arguments': idl_type.union_arguments,
+        'use_output_parameter_for_result': idl_type.use_output_parameter_for_result,
         'use_local_result': use_local_result(method),
         'v8_set_return_value': v8_set_return_value(interface.name, method, this_cpp_value),
         'v8_set_return_value_for_main_world': v8_set_return_value(interface.name, method, this_cpp_value, for_main_world=True),
+        'visible': is_visible,
         'world_suffixes': ['', 'ForMainWorld'] if 'PerWorldBindings' in extended_attributes else [''],  # [PerWorldBindings],
     }
 
 
-def argument_context(interface, method, argument, index):
+def argument_context(interface, method, argument, index, is_visible=True):
     extended_attributes = argument.extended_attributes
     idl_type = argument.idl_type
+    if is_visible:
+        idl_type.add_includes_for_type(extended_attributes)
     this_cpp_value = cpp_value(interface, method, index)
     is_variadic_wrapper_type = argument.is_variadic and idl_type.is_wrapper_type
 
+    # [TypeChecking=Interface] / [LegacyInterfaceTypeChecking]
+    has_type_checking_interface = (
+        not is_legacy_interface_type_checking(interface, method) and
+        idl_type.is_wrapper_type)
+
     if ('ImplementedInPrivateScript' in extended_attributes and
         not idl_type.is_wrapper_type and
         not idl_type.is_basic_type):
         raise Exception('Private scripts supports only primitive types and DOM wrappers.')
 
-    default_cpp_value = argument.default_cpp_value
+    set_default_value = argument.set_default_value
+    this_cpp_type = idl_type.cpp_type_args(extended_attributes=extended_attributes,
+                                           raw_type=True,
+                                           used_as_variadic_argument=argument.is_variadic)
     return {
-        'cpp_type': idl_type.cpp_type_args(extended_attributes=extended_attributes,
-                                           raw_type=True,
-                                           used_as_variadic_argument=argument.is_variadic),
+        'cpp_type': (
+            v8_types.cpp_template_type('Nullable', this_cpp_type)
+            if idl_type.is_explicit_nullable and not argument.is_variadic
+            else this_cpp_type),
         'cpp_value': this_cpp_value,
         # FIXME: check that the default value's type is compatible with the argument's
-        'default_value': default_cpp_value,
-        'enum_validation_expression': idl_type.enum_validation_expression,
+        'set_default_value': set_default_value,
+        'enum_type': idl_type.enum_type,
+        'enum_values': idl_type.enum_values,
         'handle': '%sHandle' % argument.name,
         # FIXME: remove once [Default] removed and just use argument.default_value
-        'has_default': 'Default' in extended_attributes or default_cpp_value,
-        'has_type_checking_interface':
-            (has_extended_attribute_value(interface, 'TypeChecking', 'Interface') or
-             has_extended_attribute_value(method, 'TypeChecking', 'Interface')) and
-            idl_type.is_wrapper_type,
-        'has_type_checking_unrestricted':
-            (has_extended_attribute_value(interface, 'TypeChecking', 'Unrestricted') or
-             has_extended_attribute_value(method, 'TypeChecking', 'Unrestricted')) and
-            idl_type.name in ('Float', 'Double'),
+        'has_default': 'Default' in extended_attributes or set_default_value,
+        'has_type_checking_interface': has_type_checking_interface,
         # Dictionary is special-cased, but arrays and sequences shouldn't be
         'idl_type': idl_type.base_type,
         'idl_type_object': idl_type,
         'index': index,
+        'is_callback_function': idl_type.is_callback_function,
         'is_callback_interface': idl_type.is_callback_interface,
         # FIXME: Remove generic 'Dictionary' special-casing
         'is_dictionary': idl_type.is_dictionary or idl_type.base_type == 'Dictionary',
+        'is_explicit_nullable': idl_type.is_explicit_nullable,
         'is_nullable': idl_type.is_nullable,
         'is_optional': argument.is_optional,
+        'is_variadic': argument.is_variadic,
         'is_variadic_wrapper_type': is_variadic_wrapper_type,
         'is_wrapper_type': idl_type.is_wrapper_type,
         'name': argument.name,
         'private_script_cpp_value_to_v8_value': idl_type.cpp_value_to_v8_value(
             argument.name, isolate='scriptState->isolate()',
             creation_context='scriptState->context()->Global()'),
+        'use_permissive_dictionary_conversion': 'PermissiveDictionaryConversion' in extended_attributes,
         'v8_set_return_value': v8_set_return_value(interface.name, method, this_cpp_value),
         'v8_set_return_value_for_main_world': v8_set_return_value(interface.name, method, this_cpp_value, for_main_world=True),
-        'v8_value_to_local_cpp_value': v8_value_to_local_cpp_value(argument, index, return_promise=method.returns_promise),
-        'vector_type': v8_types.cpp_ptr_type('Vector', 'HeapVector', idl_type.gc_type),
+        'v8_value_to_local_cpp_value': v8_value_to_local_cpp_value(method, argument, index),
     }
 
 
 def argument_declarations_for_private_script(interface, method):
     argument_declarations = ['LocalFrame* frame']
     argument_declarations.append('%s* holderImpl' % interface.name)
     argument_declarations.extend(['%s %s' % (argument.idl_type.cpp_type_args(
         used_as_rvalue_type=True), argument.name) for argument in method.arguments])
     if method.idl_type.name != 'void':
         argument_declarations.append('%s* %s' % (method.idl_type.cpp_type, 'result'))
     return argument_declarations
 
 
 ################################################################################
 # Value handling
 ################################################################################
 
 def cpp_value(interface, method, number_of_arguments):
     def cpp_argument(argument):
         idl_type = argument.idl_type
         if idl_type.name == 'EventListener':
             return argument.name
-        if idl_type.is_dictionary:
-            return '*%s' % argument.name
         if (idl_type.name in ['NodeFilter', 'NodeFilterOrNull',
                               'XPathNSResolver', 'XPathNSResolverOrNull']):
             # FIXME: remove this special case
             return '%s.release()' % argument.name
         return argument.name
 
     # Truncate omitted optional arguments
     arguments = method.arguments[:number_of_arguments]
     cpp_arguments = []
     if 'ImplementedInPrivateScript' in method.extended_attributes:
-        cpp_arguments.append('toFrameIfNotDetached(info.GetIsolate()->GetCurrentContext())')
+        cpp_arguments.append('toLocalFrame(toFrameIfNotDetached(info.GetIsolate()->GetCurrentContext()))')
         cpp_arguments.append('impl')
 
     if method.is_constructor:
         call_with_values = interface.extended_attributes.get('ConstructorCallWith')
     else:
         call_with_values = method.extended_attributes.get('CallWith')
     cpp_arguments.extend(v8_utilities.call_with_arguments(call_with_values))
 
     # Members of IDL partial interface definitions are implemented in C++ as
     # static member functions, which for instance members (non-static members)
     # take *impl as their first argument
     if ('PartialInterfaceImplementedAs' in method.extended_attributes and
         not 'ImplementedInPrivateScript' in method.extended_attributes and
         not method.is_static):
         cpp_arguments.append('*impl')
     cpp_arguments.extend(cpp_argument(argument) for argument in arguments)
 
-    this_union_arguments = method.idl_type and method.idl_type.union_arguments
-    if this_union_arguments:
-        cpp_arguments.extend([member_argument['cpp_value']
-                              for member_argument in this_union_arguments])
-
     if 'ImplementedInPrivateScript' in method.extended_attributes:
         if method.idl_type.name != 'void':
             cpp_arguments.append('&result')
     elif ('RaisesException' in method.extended_attributes or
         (method.is_constructor and
          has_extended_attribute_value(interface, 'RaisesException', 'Constructor'))):
         cpp_arguments.append('exceptionState')
 
+    # If a method returns an IDL dictionary or union type, the return value is
+    # passed as an argument to impl classes.
+    idl_type = method.idl_type
+    if idl_type and idl_type.use_output_parameter_for_result:
+        cpp_arguments.append('result')
+
     if method.name == 'Constructor':
         base_name = 'create'
     elif method.name == 'NamedConstructor':
         base_name = 'createForJSConstructor'
     elif 'ImplementedInPrivateScript' in method.extended_attributes:
         base_name = '%sMethod' % method.name
     else:
         base_name = v8_utilities.cpp_name(method)
 
     cpp_method_name = v8_utilities.scoped_name(interface, method, base_name)
@@ skipping 16 matching lines @@
     # [CallWith=ScriptState], [RaisesException]
     if use_local_result(method):
         if idl_type.is_explicit_nullable:
             # result is of type Nullable<T>
             cpp_value = 'result.get()'
         else:
             cpp_value = 'result'
         release = idl_type.release
 
     script_wrappable = 'impl' if inherits_interface(interface_name, 'Node') else ''
-    return idl_type.v8_set_return_value(cpp_value, extended_attributes, script_wrappable=script_wrappable, release=release, for_main_world=for_main_world)
+    return idl_type.v8_set_return_value(cpp_value, extended_attributes, script_wrappable=script_wrappable, release=release, for_main_world=for_main_world, is_static=method.is_static)
 
 
-def v8_value_to_local_cpp_variadic_value(argument, index, return_promise):
+def v8_value_to_local_cpp_variadic_value(method, argument, index, return_promise):
     assert argument.is_variadic
     idl_type = argument.idl_type
+    this_cpp_type = idl_type.cpp_type
 
-    suffix = ''
+    if method.returns_promise:
+        check_expression = 'exceptionState.hadException()'
+    else:
+        check_expression = 'exceptionState.throwIfNeeded()'
 
-    macro = 'TONATIVE_VOID_EXCEPTIONSTATE'
-    macro_args = [
-        argument.name,
-        'toImplArguments<%s>(info, %s, exceptionState)' % (idl_type.cpp_type, index),
-        'exceptionState',
-    ]
+    if idl_type.is_dictionary or idl_type.is_union_type:
+        vector_type = 'HeapVector'
+    else:
+        vector_type = 'Vector'
 
-    if return_promise:
-        suffix += '_PROMISE'
-        macro_args.extend(['info', 'V8ScriptState::current(info.GetIsolate())'])
-
-    suffix += '_INTERNAL'
-
-    return '%s%s(%s)' % (macro, suffix, ', '.join(macro_args))
+    return {
+        'assign_expression': 'toImplArguments<%s<%s>>(info, %s, exceptionState)' % (vector_type, this_cpp_type, index),
+        'check_expression': check_expression,
+        'cpp_type': this_cpp_type,
+        'cpp_name': argument.name,
+        'declare_variable': False,
+    }
 
 
-def v8_value_to_local_cpp_value(argument, index, return_promise=False):
+def v8_value_to_local_cpp_value(method, argument, index, return_promise=False, restricted_float=False):
     extended_attributes = argument.extended_attributes
     idl_type = argument.idl_type
     name = argument.name
     if argument.is_variadic:
-        return v8_value_to_local_cpp_variadic_value(argument, index, return_promise)
+        return v8_value_to_local_cpp_variadic_value(method, argument, index, return_promise)
     return idl_type.v8_value_to_local_cpp_value(extended_attributes, 'info[%s]' % index,
-                                                name, index=index, declare_variable=False, return_promise=return_promise)
+                                                name, index=index, declare_variable=False,
+                                                use_exception_state=method.returns_promise,
+                                                restricted_float=restricted_float)
 
 
 ################################################################################
 # Auxiliary functions
 ################################################################################
 
 # [NotEnumerable]
-def property_attributes(method):
+def property_attributes(interface, method):
     extended_attributes = method.extended_attributes
     property_attributes_list = []
     if 'NotEnumerable' in extended_attributes:
         property_attributes_list.append('v8::DontEnum')
-    if 'Unforgeable' in extended_attributes:
+    if is_unforgeable(interface, method):
         property_attributes_list.append('v8::ReadOnly')
     if property_attributes_list:
         property_attributes_list.insert(0, 'v8::DontDelete')
     return property_attributes_list
 
 
-def union_member_argument_context(idl_type, index):
-    """Returns a context of union member for argument."""
-    this_cpp_value = 'result%d' % index
-    this_cpp_type = idl_type.cpp_type
-    this_cpp_type_initializer = idl_type.cpp_type_initializer
-    cpp_return_value = this_cpp_value
+def argument_set_default_value(argument):
+    idl_type = argument.idl_type
+    default_value = argument.default_value
+    if not default_value:
+        return None
+    if idl_type.is_dictionary:
+        if not argument.default_value.is_null:
+            raise Exception('invalid default value for dictionary type')
+        return None
+    if idl_type.is_array_or_sequence_type:
+        if default_value.value != '[]':
+            raise Exception('invalid default value for sequence type: %s' % default_value.value)
+        # Nothing to do when we set an empty sequence as default value, but we
+        # need to return non-empty value so that we don't generate method calls
+        # without this argument.
+        return '/* Nothing to do */'
+    if idl_type.is_union_type:
+        if argument.default_value.is_null:
+            if not idl_type.includes_nullable_type:
+                raise Exception('invalid default value for union type: null for %s'
+                                % idl_type.name)
+            # Union container objects are "null" initially.
+            return '/* null default value */'
+        if isinstance(default_value.value, basestring):
+            member_type = idl_type.string_member_type
+        elif isinstance(default_value.value, (int, float)):
+            member_type = idl_type.numeric_member_type
+        elif isinstance(default_value.value, bool):
+            member_type = idl_type.boolean_member_type
+        else:
+            member_type = None
+        if member_type is None:
+            raise Exception('invalid default value for union type: %r for %s'
+                            % (default_value.value, idl_type.name))
+        member_type_name = (member_type.inner_type.name
+                            if member_type.is_nullable else
+                            member_type.name)
+        return '%s.set%s(%s)' % (argument.name, member_type_name,
+                                 member_type.literal_cpp_value(default_value))
+    return '%s = %s' % (argument.name,
+                        idl_type.literal_cpp_value(default_value))
 
-    if not idl_type.cpp_type_has_null_value:
-        this_cpp_type = v8_types.cpp_template_type('Nullable', this_cpp_type)
-        this_cpp_type_initializer = ''
-        cpp_return_value = '%s.get()' % this_cpp_value
-
-    if idl_type.is_string_type:
-        null_check_value = '!%s.isNull()' % this_cpp_value
-    else:
-        null_check_value = this_cpp_value
-
-    return {
-        'cpp_type': this_cpp_type,
-        'cpp_type_initializer': this_cpp_type_initializer,
-        'cpp_value': this_cpp_value,
-        'null_check_value': null_check_value,
-        'v8_set_return_value': idl_type.v8_set_return_value(
-            cpp_value=cpp_return_value,
-            release=idl_type.release),
-    }
-
-
-def union_arguments(idl_type):
-    return [union_member_argument_context(member_idl_type, index)
-            for index, member_idl_type
-            in enumerate(idl_type.member_types)]
-
-
-def argument_default_cpp_value(argument):
-    if argument.idl_type.is_dictionary:
-        # We always create impl objects for IDL dictionaries.
-        return '%s::create()' % argument.idl_type.base_type
-    if not argument.default_value:
-        return None
-    return argument.idl_type.literal_cpp_value(argument.default_value)
-
-IdlTypeBase.union_arguments = None
-IdlUnionType.union_arguments = property(union_arguments)
-IdlArgument.default_cpp_value = property(argument_default_cpp_value)
+IdlArgument.set_default_value = property(argument_set_default_value)
 
 
 def method_returns_promise(method):
     return method.idl_type and method.idl_type.name == 'Promise'
 
 IdlOperation.returns_promise = property(method_returns_promise)
 
 
 def argument_conversion_needs_exception_state(method, argument):
     idl_type = argument.idl_type
     return (idl_type.v8_conversion_needs_exception_state or
             argument.is_variadic or
-            (method.returns_promise and (idl_type.is_string_type or
-                                         idl_type.is_enum)))
+            (method.returns_promise and idl_type.is_string_type))