[kernel] Don't emit field initializers in a redirecting constructor

runtime/vm/kernel_binary_flowgraph.cc

 // Copyright (c) 2016, 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/kernel_binary_flowgraph.h"
 
 #include "vm/compiler.h"
 #include "vm/longjump.h"
 #include "vm/object_store.h"
 
@@ skipping 2906 matching lines @@
   instructions += LoadLocal(scopes()->this_variable);
   instructions += BuildExpression();
   instructions += flow_graph_builder_->StoreInstanceFieldGuarded(field, true);
   return instructions;
 }
 
 Fragment StreamingFlowGraphBuilder::BuildInitializers(
     intptr_t constructor_class_parent_offset) {
   Fragment instructions;
 
+  // Start by getting the position of the constructors initializer.
+  intptr_t initializers_offset = -1;
+  {
+    AlternativeReadingScope alt(reader_);
+    SkipFunctionNode();  // read constructors function node.
+    initializers_offset = ReaderOffset();
+  }
+
   // These come from:
   //   class A {
   //     var x = (expr);
   //   }
+  // We don't want to do that when this is a Redirecting Constructors though
+  // (i.e. has a single initializer being of type kRedirectingInitializer).
+  bool is_redirecting_constructor = false;
   {
+    AlternativeReadingScope alt(reader_, initializers_offset);
+    intptr_t list_length = ReadListLength();  // read initializers list length.
+    if (list_length == 1) {
+      Tag tag = ReadTag();
+      if (tag == kRedirectingInitializer) is_redirecting_constructor = true;
+    }
+  }
+
+  if (!is_redirecting_constructor) {
     AlternativeReadingScope alt(reader_, constructor_class_parent_offset);
     ReadClassUntilFields();                   // read first part of class.
     intptr_t list_length = ReadListLength();  // read fields list length.
 
     for (intptr_t i = 0; i < list_length; ++i) {
       intptr_t field_offset = ReaderOffset();
       NameIndex canonical_name;
       TokenPosition position;
       TokenPosition end_position;
       word flags;
@@ skipping 14 matching lines @@
     }
   }
 
   // These to come from:
   //   class A {
   //     var x;
   //     var y;
   //     A(this.x) : super(expr), y = (expr);
   //   }
   {
-    AlternativeReadingScope alt(reader_);
-    SkipFunctionNode();  // read constructors function node.
-
+    AlternativeReadingScope alt(reader_, initializers_offset);
     intptr_t list_length = ReadListLength();  // read initializers list length.
     for (intptr_t i = 0; i < list_length; ++i) {
       Tag tag = ReadTag();
       switch (tag) {
         case kInvalidInitializer:
           UNIMPLEMENTED();
           return Fragment();
         case kFieldInitializer: {
           NameIndex canonical_name =
               ReadCanonicalNameReference();  // read field_reference.
@@ skipping 15 matching lines @@
           argument_count += 1;
 
           const Function& target = Function::ZoneHandle(
               Z, H.LookupConstructorByKernelConstructor(canonical_target));
           instructions += StaticCall(TokenPosition::kNoSource, target,
                                      argument_count, argument_names);
           instructions += Drop();
           break;
         }
         case kRedirectingInitializer: {
           NameIndex canonical_target =

[Vyacheslav Egorov (Google), 2017/06/16 11:14:28]

ASSERT(list_length == 1) here

               ReadCanonicalNameReference();  // read target_reference.
 
           instructions += LoadLocal(scopes()->this_variable);
           instructions += PushArgument();
 
           // TODO(jensj): ASSERT(init->arguments()->types().length() == 0);
           Array& argument_names = Array::ZoneHandle(Z);
           intptr_t argument_count;
           instructions += BuildArguments(&argument_names,
                                          &argument_count);  // read arguments.
@@ skipping 4135 matching lines @@
     metadata_values.SetAt(i, value);
   }
 
   return metadata_values.raw();
 }
 
 }  // namespace kernel
 }  // namespace dart
 
 #endif  // !defined(DART_PRECOMPILED_RUNTIME)