Stop resolving classes prematurely in the vm (issue 11023).

runtime/vm/parser.cc

Index: runtime/vm/parser.cc
===================================================================
--- runtime/vm/parser.cc	(revision 24964)
+++ runtime/vm/parser.cc	(working copy)
@@ -1281,7 +1281,7 @@
       // mode, because they are part of the function type of closurized
       // functions appearing in type tests with typedefs.
       parameter.type = &AbstractType::ZoneHandle(
-          ParseType(is_top_level_ ? ClassFinalizer::kTryResolve :
+          ParseType(is_top_level_ ? ClassFinalizer::kResolveTypeParameters :
                                     ClassFinalizer::kCanonicalize));
     } else {
       parameter.type = &Type::ZoneHandle(Type::DynamicType());
@@ -2800,20 +2800,17 @@
     ConsumeToken();
     const intptr_t type_pos = TokenPos();
     const AbstractType& type = AbstractType::Handle(
-        ParseType(ClassFinalizer::kTryResolve));
-    if (!type.IsMalformed() &&
-        (type.IsTypeParameter() || type.IsDynamicType())) {
+        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.
           current_class(),
           type_pos,
-          ClassFinalizer::kTryResolve,  // No compile-time error.
-          "factory '%s' may not redirect to %s'%s'",
+          ClassFinalizer::kResolveTypeParameters,  // No compile-time error.
+          "factory '%s' may not redirect to type parameter '%s'",
           method->name->ToCString(),
-          type.IsTypeParameter() ? "type parameter " : "",
-          type.IsTypeParameter() ?
-              String::Handle(type.UserVisibleName()).ToCString() : "dynamic");
+          String::Handle(type.UserVisibleName()).ToCString());
     } else {
       redirection_type ^= type.raw();
     }
@@ -3022,11 +3019,15 @@
       // invocation/compilation.
       // For instance fields, the expression is parsed when a constructor
       // is compiled.
-      // For static fields with very simple initializer expressions
+      // For static const fields with very simple initializer expressions
       // (e.g. a literal number or string) we optimize away the
       // kConstImplicitGetter and initialize the field here.
+      // We also do it for static final non-const fields, but only in production
+      // mode.
 
-      if (field->has_static && (field->has_final || field->has_const) &&
+      if (field->has_static &&
+          (field->has_const ||
+           (!FLAG_enable_type_checks && field->has_final)) &&
           (LookaheadToken(1) == Token::kSEMICOLON)) {
         has_simple_literal = IsSimpleLiteral(*field->type, &init_value);
       }
@@ -3215,7 +3216,7 @@
         // because getters and setters could be closurized at some time (not
         // supported yet).
         member.type = &AbstractType::ZoneHandle(
-            ParseType(ClassFinalizer::kTryResolve));
+            ParseType(ClassFinalizer::kResolveTypeParameters));
       }
     }
   }
@@ -3464,18 +3465,13 @@
   if (CurrentToken() == Token::kEXTENDS) {
     ConsumeToken();
     const intptr_t type_pos = TokenPos();
-    super_type = ParseType(ClassFinalizer::kTryResolve);
+    super_type = ParseType(ClassFinalizer::kResolveTypeParameters);
     if (super_type.IsTypeParameter()) {
       ErrorMsg(type_pos,
                "class '%s' may not extend type parameter '%s'",
                class_name.ToCString(),
                String::Handle(super_type.UserVisibleName()).ToCString());
     }
-    if (super_type.IsDynamicType()) {
-      ErrorMsg(type_pos,
-               "class '%s' may not extend 'dynamic'",
-               class_name.ToCString());
-    }
     if (CurrentToken() == Token::kWITH) {
       super_type = ParseMixins(super_type);
     }
@@ -3671,7 +3667,7 @@
 
   const intptr_t type_pos = TokenPos();
   AbstractType& type =
-      AbstractType::Handle(ParseType(ClassFinalizer::kTryResolve));
+      AbstractType::Handle(ParseType(ClassFinalizer::kResolveTypeParameters));
   if (type.IsTypeParameter()) {
     ErrorMsg(type_pos,
              "class '%s' may not extend type parameter '%s'",
@@ -3787,7 +3783,7 @@
   // result type.
   if (!result_type.IsNull()) {
     ResolveTypeFromClass(function_type_alias,
-                         ClassFinalizer::kTryResolve,
+                         ClassFinalizer::kResolveTypeParameters,
                          &result_type);
   }
   // Parse the formal parameters of the function type.
@@ -3984,7 +3980,7 @@
       type_parameter ^= type_parameters.TypeAt(i);
       type_parameter_bound = type_parameter.bound();
       ResolveTypeFromClass(cls,
-                           ClassFinalizer::kTryResolve,
+                           ClassFinalizer::kResolveTypeParameters,
                            &type_parameter_bound);
       type_parameter.set_bound(type_parameter_bound);
     }
@@ -4046,15 +4042,12 @@
   do {
     ConsumeToken();
     intptr_t interface_pos = TokenPos();
-    interface = ParseType(ClassFinalizer::kTryResolve);
+    interface = ParseType(ClassFinalizer::kResolveTypeParameters);
     if (interface.IsTypeParameter()) {
       ErrorMsg(interface_pos,
                "type parameter '%s' may not be used in interface list",
                String::Handle(interface.UserVisibleName()).ToCString());
     }
-    if (interface.IsDynamicType()) {
-      ErrorMsg(interface_pos, "'dynamic' may not be used in interface list");
-    }
     all_interfaces.Add(interface);
   } while (CurrentToken() == Token::kCOMMA);
   cls_interfaces = Array::MakeArray(all_interfaces);
@@ -4080,7 +4073,7 @@
   do {
     ConsumeToken();
     const intptr_t mixin_pos = TokenPos();
-    mixin_type = ParseType(ClassFinalizer::kTryResolve);
+    mixin_type = ParseType(ClassFinalizer::kResolveTypeParameters);
     if (mixin_type.IsTypeParameter()) {
       ErrorMsg(mixin_pos,
                "mixin type '%s' may not be a type parameter",
@@ -4113,7 +4106,7 @@
     // to get the copy is to rewind the parser, parse the mixin type
     // again and steal its type arguments.
     SetPosition(mixin_pos);
-    mixin_type = ParseType(ClassFinalizer::kTryResolve);
+    mixin_type = ParseType(ClassFinalizer::kResolveTypeParameters);
     mixin_type_arguments = mixin_type.arguments();
 
     mixin_application_type = Type::New(mixin_application,
@@ -4136,7 +4129,7 @@
   const bool is_static = true;
   const AbstractType& type =
       AbstractType::ZoneHandle(ParseConstFinalVarOrType(
-          FLAG_enable_type_checks ? ClassFinalizer::kTryResolve :
+          FLAG_enable_type_checks ? ClassFinalizer::kResolveTypeParameters :
                                     ClassFinalizer::kIgnore));
   Field& field = Field::Handle();
   Function& getter = Function::Handle();
@@ -4175,7 +4168,8 @@
       ConsumeToken();
       Instance& field_value = Instance::Handle(Object::sentinel().raw());
       bool has_simple_literal = false;
-      if (is_final && (LookaheadToken(1) == Token::kSEMICOLON)) {
+      if ((is_const || (!FLAG_enable_type_checks && is_final)) &&
+          (LookaheadToken(1) == Token::kSEMICOLON)) {
         has_simple_literal = IsSimpleLiteral(type, &field_value);
       }
       SkipExpr();
@@ -4234,7 +4228,7 @@
     // Parse optional type.
     if ((CurrentToken() == Token::kIDENT) &&
         (LookaheadToken(1) != Token::kLPAREN)) {
-      result_type = ParseType(ClassFinalizer::kTryResolve);
+      result_type = ParseType(ClassFinalizer::kResolveTypeParameters);
     }
   }
   const intptr_t name_pos = TokenPos();
@@ -4328,7 +4322,7 @@
       ConsumeToken();
       result_type = Type::VoidType();
     } else {
-      result_type = ParseType(ClassFinalizer::kTryResolve);
+      result_type = ParseType(ClassFinalizer::kResolveTypeParameters);
     }
     is_getter = (CurrentToken() == Token::kGET);
     if (CurrentToken() == Token::kGET || CurrentToken() == Token::kSET) {
@@ -5324,30 +5318,41 @@
 
 
 bool Parser::IsSimpleLiteral(const AbstractType& type, Instance* value) {
-  bool no_check = type.IsDynamicType();
-  if ((CurrentToken() == Token::kINTEGER) &&
-      (no_check || type.IsIntType() || type.IsNumberType())) {
+  // Assigning null never causes a type error.
+  if (CurrentToken() == Token::kNULL) {
+    *value = Instance::null();
+    return true;
+  }
+  // If the type of the const field is guaranteed to be instantiated once
+  // resolved at class finalization time, and if the type of the literal is one
+  // of int, double, String, or bool, then preset the field with the value and
+  // perform the type check (in checked mode only) at finalization time.
+  if (type.IsTypeParameter() ||
+      (type.arguments() != AbstractTypeArguments::null())) {
+    // Type parameters are always resolved eagerly by the parser and never
+    // resolved later by the class finalizer. Therefore, we know here that if
+    // 'type' is not a type parameter (an unresolved type will not get resolved
+    // to a type parameter later) and if 'type' has no type arguments, then it
+    // will be instantiated at class finalization time. Otherwise, we return
+    // false, since the type test would not be possible at finalization time for
+    // an uninstantiated type.
+    return false;
+  }
+  if (CurrentToken() == Token::kINTEGER) {
     *value = CurrentIntegerLiteral();
     return true;
-  } else if ((CurrentToken() == Token::kDOUBLE) &&
-      (no_check || type.IsDoubleType() || type.IsNumberType())) {
+  } else if (CurrentToken() == Token::kDOUBLE) {
     *value = CurrentDoubleLiteral();
     return true;
-  } else if ((CurrentToken() == Token::kSTRING) &&
-      (no_check || type.IsStringType())) {
+  } else if (CurrentToken() == Token::kSTRING) {
     *value = CurrentLiteral()->raw();
     return true;
-  } else if ((CurrentToken() == Token::kTRUE) &&
-      (no_check || type.IsBoolType())) {
+  } else if (CurrentToken() == Token::kTRUE) {
     *value = Bool::True().raw();
     return true;
-  } else if ((CurrentToken() == Token::kFALSE) &&
-      (no_check || type.IsBoolType())) {
+  } else if (CurrentToken() == Token::kFALSE) {
     *value = Bool::False().raw();
     return true;
-  } else if (CurrentToken() == Token::kNULL) {
-    *value = Instance::null();
-    return true;
   }
   return false;
 }
@@ -8002,7 +8007,7 @@
 void Parser::ResolveTypeFromClass(const Class& scope_class,
                                   ClassFinalizer::FinalizationKind finalization,
                                   AbstractType* type) {
-  ASSERT(finalization >= ClassFinalizer::kTryResolve);
+  ASSERT(finalization >= ClassFinalizer::kResolveTypeParameters);
   ASSERT(type != NULL);
   if (type->IsResolved()) {
     return;
@@ -8050,25 +8055,29 @@
           return;
         }
       }
-      // Resolve classname in the scope of the current library.
-      Error& error = Error::Handle();
-      // If we finalize a type expression, as opposed to a type annotation, we
-      // tell the resolver (by passing NULL) to immediately report an ambiguous
-      // type as a compile time error.
-      resolved_type_class = ResolveClassInCurrentLibraryScope(
-          unresolved_class.token_pos(),
-          unresolved_class_name,
-          finalization >= ClassFinalizer::kCanonicalizeExpression ?
-              NULL : &error);
-      if (!error.IsNull()) {
-        *type = ClassFinalizer::NewFinalizedMalformedType(
-            error,
-            scope_class,
+      // The referenced class may not have been parsed yet. It would be wrong
+      // to resolve it too early to an imported class of the same name.
+      if (finalization > ClassFinalizer::kResolveTypeParameters) {
+        // Resolve classname in the scope of the current library.
+        Error& error = Error::Handle();
+        // If we finalize a type expression, as opposed to a type annotation,
+        // we tell the resolver (by passing NULL) to immediately report an
+        // ambiguous type as a compile time error.
+        resolved_type_class = ResolveClassInCurrentLibraryScope(
             unresolved_class.token_pos(),
-            finalization,
-            "cannot resolve class '%s'",
-            unresolved_class_name.ToCString());
-        return;
+            unresolved_class_name,
+            finalization >= ClassFinalizer::kCanonicalizeExpression ?
+                NULL : &error);
+        if (!error.IsNull()) {
+          *type = ClassFinalizer::NewFinalizedMalformedType(
+              error,
+              scope_class,
+              unresolved_class.token_pos(),
+              finalization,
+              "cannot resolve class '%s'",
+              unresolved_class_name.ToCString());
+          return;
+        }
       }
     } else {
       LibraryPrefix& lib_prefix =
@@ -8530,8 +8539,8 @@
           if (first_lib_url.raw() == lib.url()) {
             ambiguous_ref_error = FormatErrorMsg(
                 script_, ident_pos, "Error",
-                "ambiguous reference: "
-                "'%s' as library '%s' is imported multiple times",
+                "ambiguous reference to '%s', "
+                "as library '%s' is imported multiple times",
                 name.ToCString(),
                 first_lib_url.ToCString());
           } else {
@@ -8850,7 +8859,7 @@
     parameterized_type.set_arguments(Object::null_abstract_type_arguments());
     parameterized_type.set_malformed_error(malformed_error);
   }
-  if (finalization >= ClassFinalizer::kTryResolve) {
+  if (finalization >= ClassFinalizer::kResolveTypeParameters) {
     ResolveTypeFromClass(current_class(), finalization, &type);
     if (finalization >= ClassFinalizer::kCanonicalize) {
       type ^= ClassFinalizer::FinalizeType(current_class(), type, finalization);
@@ -8953,6 +8962,7 @@
       AstNode* elem = element_list[i];
       // Arguments have been evaluated to a literal value already.
       ASSERT(elem->IsLiteralNode());
+      ASSERT(!is_top_level_);  // We cannot check unresolved types.
       if (FLAG_enable_type_checks &&
           !element_type.IsDynamicType() &&
           (!elem->AsLiteralNode()->literal().IsNull() &&
@@ -9149,6 +9159,7 @@
       AstNode* arg = kv_pairs_list[i];
       // Arguments have been evaluated to a literal value already.
       ASSERT(arg->IsLiteralNode());
+      ASSERT(!is_top_level_);  // We cannot check unresolved types.
       if (FLAG_enable_type_checks &&
           ((i % 2) == 1) &&  // Check values only, not keys.
           !value_type.IsDynamicType() &&
@@ -9305,7 +9316,7 @@
         Error::Handle(),  // No previous error.
         current_class(),
         type_pos,
-        ClassFinalizer::kTryResolve,  // No compile-time error.
+        ClassFinalizer::kResolveTypeParameters,  // No compile-time error.
         "%s'%s' cannot be instantiated",
         type.IsTypeParameter() ? "type parameter " : "",
         type.IsTypeParameter() ?
@@ -9371,7 +9382,7 @@
             Error::Handle(),  // No previous error.
             current_class(),
             call_pos,
-            ClassFinalizer::kTryResolve,  // No compile-time error.
+            ClassFinalizer::kResolveTypeParameters,  // No compile-time error.
             "class '%s' has no constructor or factory named '%s'",
             String::Handle(type_class.Name()).ToCString(),
             external_constructor_name.ToCString());
@@ -9482,6 +9493,7 @@
       if (!type_bound.IsNull()) {
         ASSERT(!type_bound.IsMalformed());
         Error& malformed_error = Error::Handle();
+        ASSERT(!is_top_level_);  // We cannot check unresolved types.
         if (!const_instance.IsInstanceOf(type_bound,
                                          TypeArguments::Handle(),
                                          &malformed_error)) {
@@ -9489,7 +9501,7 @@
               malformed_error,
               current_class(),
               new_pos,
-              ClassFinalizer::kTryResolve,  // No compile-time error.
+              ClassFinalizer::kResolveTypeParameters,  // No compile-time error.
               "const factory result is not an instance of '%s'",
               String::Handle(type_bound.UserVisibleName()).ToCString());
           new_object = ThrowTypeError(new_pos, type_bound);