Disallow explicit parameter default values in redirecting factory (issue 13662).

runtime/vm/parser.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/parser.h"
 
 #include "lib/invocation_mirror.h"
 #include "vm/bigint_operations.h"
 #include "vm/bootstrap.h"
 #include "vm/class_finalizer.h"
@@ skipping 426 matching lines @@
 struct ParamList {
   ParamList() {
     Clear();
   }
 
   void Clear() {
     num_fixed_parameters = 0;
     num_optional_parameters = 0;
     has_optional_positional_parameters = false;
     has_optional_named_parameters = false;
+    has_explicit_default_values = false;
     has_field_initializer = false;
     implicitly_final = false;
     skipped = false;
     this->parameters = new ZoneGrowableArray<ParamDesc>();
   }
 
   void AddFinalParameter(intptr_t name_pos,
                          const String* name,
                          const AbstractType* type) {
     this->num_fixed_parameters++;
@@ skipping 25 matching lines @@
   }
 
   void SetImplicitlyFinal() {
     implicitly_final = true;
   }
 
   int num_fixed_parameters;
   int num_optional_parameters;
   bool has_optional_positional_parameters;
   bool has_optional_named_parameters;
+  bool has_explicit_default_values;
   bool has_field_initializer;
   bool implicitly_final;
   bool skipped;
   ZoneGrowableArray<ParamDesc>* parameters;
 };
 
 
 struct MemberDesc {
   MemberDesc() {
     Clear();
@@ skipping 969 matching lines @@
          !params->has_optional_named_parameters) ||
         !allow_explicit_default_value) {
       ErrorMsg("parameter must not specify a default value");
     }
     if (params->has_optional_positional_parameters) {
       ExpectToken(Token::kASSIGN);
     } else {
       ExpectToken(Token::kCOLON);
     }
     params->num_optional_parameters++;
+    params->has_explicit_default_values = true;  // Also if explicitly NULL.
     if (is_top_level_) {
       // Skip default value parsing.
       SkipExpr();
     } else {
       const Object& const_value = ParseConstExpr()->literal();
       parameter.default_value = &const_value;
     }
   } else {
     if (params->has_optional_positional_parameters ||
         params->has_optional_named_parameters) {
@@ skipping 1525 matching lines @@
       ErrorMsg(method->name_pos, "illegal %s parameters",
                method->IsGetter() ? "getter" : "setter");
     }
   }
 
   // Parse redirecting factory constructor.
   Type& redirection_type = Type::Handle();
   String& redirection_identifier = String::Handle();
   bool is_redirecting = false;
   if (method->IsFactory() && (CurrentToken() == Token::kASSIGN)) {
+    // Default parameter values are disallowed in redirecting factories.
+    if (method->params.has_explicit_default_values) {
+      ErrorMsg("redirecting factory '%s' may not specify a default value "

[hausner, 2013/10/25 22:26:38]

Should this message use plural, like: may not specify default values for
optional parameters?

[regis, 2013/10/25 22:54:42]

The spec uses singular, but I changed it to plural here.

+               "for an optional parameter",
+               method->name->ToCString());
+    }
     ConsumeToken();
     const intptr_t type_pos = TokenPos();
     is_redirecting = true;
     const AbstractType& type = AbstractType::Handle(
         ParseType(ClassFinalizer::kResolveTypeParameters));
     if (!type.IsMalformed() && type.IsTypeParameter()) {
       // Replace the type with a malformed type and compile a throw when called.
       redirection_type = ClassFinalizer::NewFinalizedMalformedType(
           Error::Handle(),  // No previous error.
           script_,
@@ skipping 7543 matching lines @@
 void Parser::SkipQualIdent() {
   ASSERT(IsIdentifier());
   ConsumeToken();
   if (CurrentToken() == Token::kPERIOD) {
     ConsumeToken();  // Consume the kPERIOD token.
     ExpectIdentifier("identifier expected after '.'");
   }
 }
 
 }  // namespace dart