Fix spread array inside array literal

src/ast.cc

 // Copyright 2012 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.
 
 #include "src/ast.h"
 
 #include <cmath>  // For isfinite.
 #include "src/builtins.h"
 #include "src/code-stubs.h"
 #include "src/contexts.h"
@@ skipping 487 matching lines @@
       (max_element_index <= 32) || ((2 * elements) >= max_element_index);
   has_elements_ = elements > 0;
   set_is_simple(is_simple);
   set_depth(depth_acc);
 }
 
 
 void ArrayLiteral::BuildConstantElements(Isolate* isolate) {
   if (!constant_elements_.is_null()) return;
 
+  // Find the first spread; everything before that is part of
+  // the constant elements.
+  // TODO(adamk): Store constant length in the AST.
+  int constants_length = values()->length();
+  for (int i = 0; i < values()->length(); i++) {
+    if (values()->at(i)->IsSpread()) {
+      constants_length = i;

[caitp (gmail), 2015/07/14 05:49:03]

Looks like you just need a `break` here to make this work

[caitp (gmail), 2015/07/14 05:49:53]

Otherwise if there are multiple spread elements, it will make the constant
length too high

[adamk, 2015/07/14 16:04:55]

Oops, indeed, I refactored this from a different approach below.

+    }
+  }
+
   // Allocate a fixed array to hold all the object literals.
   Handle<JSArray> array = isolate->factory()->NewJSArray(
-      FAST_HOLEY_SMI_ELEMENTS, values()->length(), values()->length(),
+      FAST_HOLEY_SMI_ELEMENTS, constants_length, constants_length,
       Strength::WEAK, INITIALIZE_ARRAY_ELEMENTS_WITH_HOLE);
 
   // Fill in the literals.
   bool is_simple = true;
   int depth_acc = 1;
   bool is_holey = false;
   int array_index = 0;
-  for (int n = values()->length(); array_index < n; array_index++) {
+  for (; array_index < constants_length; array_index++) {
     Expression* element = values()->at(array_index);
-    if (element->IsSpread()) break;
+    DCHECK(!element->IsSpread());
     MaterializedLiteral* m_literal = element->AsMaterializedLiteral();
     if (m_literal != NULL) {
       m_literal->BuildConstants(isolate);
       if (m_literal->depth() + 1 > depth_acc) {
         depth_acc = m_literal->depth() + 1;
       }
     }
 
     // New handle scope here, needs to be after BuildContants().
     HandleScope scope(isolate);
     Handle<Object> boilerplate_value = GetBoilerplateValue(element, isolate);
     if (boilerplate_value->IsTheHole()) {
       is_holey = true;
       continue;
     }
 
     if (boilerplate_value->IsUninitialized()) {
       boilerplate_value = handle(Smi::FromInt(0), isolate);
       is_simple = false;
     }
 
     JSObject::AddDataElement(array, array_index, boilerplate_value, NONE)
         .Assert();
   }
 
-  if (array_index != values()->length()) {
-    JSArray::SetLength(array, array_index);
-  }
   JSObject::ValidateElements(array);
   Handle<FixedArrayBase> element_values(array->elements());
 
   // Simple and shallow arrays can be lazily copied, we transform the
   // elements array to a copy-on-write array.
   if (is_simple && depth_acc == 1 && array_index > 0 &&
       array->HasFastSmiOrObjectElements()) {
     element_values->set_map(isolate->heap()->fixed_cow_array_map());
   }
 
@@ skipping 586 matching lines @@
 bool Literal::Match(void* literal1, void* literal2) {
   const AstValue* x = static_cast<Literal*>(literal1)->raw_value();
   const AstValue* y = static_cast<Literal*>(literal2)->raw_value();
   return (x->IsString() && y->IsString() && x->AsString() == y->AsString()) ||
          (x->IsNumber() && y->IsNumber() && x->AsNumber() == y->AsNumber());
 }
 
 
 }  // namespace internal
 }  // namespace v8