[strong] Declaration-after-use errors.

src/variables.h

 // Copyright 2011 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.
 
 #ifndef V8_VARIABLES_H_
 #define V8_VARIABLES_H_
 
 #include "src/ast-value-factory.h"
 #include "src/zone.h"
 
 namespace v8 {
 namespace internal {
 
 // The AST refers to variables via VariableProxies - placeholders for the actual
 // variables. Variables themselves are never directly referred to from the AST,
 // they are maintained by scopes, and referred to from VariableProxies and Slots
 // after binding and variable allocation.
 
 class Variable: public ZoneObject {
  public:
-  enum Kind { NORMAL, THIS, NEW_TARGET, ARGUMENTS };
+  enum Kind { NORMAL, FUNCTION, THIS, NEW_TARGET, ARGUMENTS };

[arv (Not doing code reviews), 2015/02/23 14:45:55]

I find this change strange. How is FUNCTION related to the other ones?

[marja, 2015/02/24 13:29:35]

The previous NORMAL is split into NORMAL and FUNCTION, to distinguish
declarations like:

let x = 0; // NORMAL

from

function x() { } // FUNCTION

In addition:

let x = function() { ..} // NORMAL

This is needed so that we can make this work:

function foo() {
  bar; // ok
  bar2; // not ok
}

function bar() { }
let bar2 = 0;

... it's not necessary that this information is carried in the Kind; but it
seemed suitable since nothing checked for == NORMAL (only == THIS, ==
ARGUMENTS), so splitting NORMAL was feasible, and, I don't fully understand what
exactly this "Kind" is, except intuitively "it's what kind of a variable it is",
and for that, function seemed a suitable addition.

 
   enum Location {
     // Before and during variable allocation, a variable whose location is
     // not yet determined.  After allocation, a variable looked up as a
     // property on the global object (and possibly absent).  name() is the
     // variable name, index() is invalid.
     UNALLOCATED,
 
     // A slot in the parameter section on the stack.  index() is the
     // parameter index, counting left-to-right.  The receiver is index -1;
@@ skipping 10 matching lines @@
     CONTEXT,
 
     // A named slot in a heap context.  name() is the variable name in the
     // context object on the heap, with lookup starting at the current
     // context.  index() is invalid.
     LOOKUP
   };
 
   Variable(Scope* scope, const AstRawString* name, VariableMode mode,
            bool is_valid_ref, Kind kind, InitializationFlag initialization_flag,
-           MaybeAssignedFlag maybe_assigned_flag = kNotAssigned);
+           int position, MaybeAssignedFlag maybe_assigned_flag = kNotAssigned);
 
   // Printing support
   static const char* Mode2String(VariableMode mode);
 
   bool IsValidReference() { return is_valid_ref_; }
 
   // The source code for an eval() call may refer to a variable that is
   // in an outer scope about which we don't know anything (it may not
   // be the script scope). scope() is NULL in that case. Currently the
   // scope is only used to follow the context chain length.
   Scope* scope() const { return scope_; }
 
   Handle<String> name() const { return name_->string(); }
   const AstRawString* raw_name() const { return name_; }
   VariableMode mode() const { return mode_; }
+  int position() const { return position_; }
   bool has_forced_context_allocation() const {
     return force_context_allocation_;
   }
   void ForceContextAllocation() {
     DCHECK(mode_ != TEMPORARY);
     force_context_allocation_ = true;
   }
   bool is_used() { return is_used_; }
   void set_is_used() { is_used_ = true; }
   MaybeAssignedFlag maybe_assigned() const { return maybe_assigned_; }
@@ skipping 13 matching lines @@
   bool IsContextSlot() const { return location_ == CONTEXT; }
   bool IsLookupSlot() const { return location_ == LOOKUP; }
   bool IsGlobalObjectProperty() const;
 
   bool is_dynamic() const { return IsDynamicVariableMode(mode_); }
   bool is_const_mode() const { return IsImmutableVariableMode(mode_); }
   bool binding_needs_init() const {
     return initialization_flag_ == kNeedsInitialization;
   }
 
+  bool is_function() const { return kind_ == FUNCTION; }
   bool is_this() const { return kind_ == THIS; }
   bool is_new_target() const { return kind_ == NEW_TARGET; }
   bool is_arguments() const { return kind_ == ARGUMENTS; }
 
   // True if the variable is named eval and not known to be shadowed.
   bool is_possibly_eval(Isolate* isolate) const {
     return IsVariable(isolate->factory()->eval_string());
   }
 
   Variable* local_if_not_shadowed() const {
@@ skipping 16 matching lines @@
     index_ = index;
   }
 
   static int CompareIndex(Variable* const* v, Variable* const* w);
 
  private:
   Scope* scope_;
   const AstRawString* name_;
   VariableMode mode_;
   Kind kind_;
+  int position_;
   Location location_;
   int index_;
   int initializer_position_;
 
   // If this field is set, this variable references the stored locally bound
   // variable, but it might be shadowed by variable bindings introduced by
   // sloppy 'eval' calls between the reference scope (inclusive) and the
   // binding scope (exclusive).
   Variable* local_if_not_shadowed_;
 
   // Valid as a reference? (const and this are not valid, for example)
   bool is_valid_ref_;
 
   // Usage info.
   bool force_context_allocation_;  // set by variable resolver
   bool is_used_;
   InitializationFlag initialization_flag_;
   MaybeAssignedFlag maybe_assigned_;
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_VARIABLES_H_