[strong] Fix scoping related errors for methods.

src/scopes.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/v8.h"
 
 #include "src/scopes.h"
 
 #include "src/accessors.h"
 #include "src/bootstrapper.h"
@@ skipping 780 matching lines @@
 static const char* Header(ScopeType scope_type) {
   switch (scope_type) {
     case EVAL_SCOPE: return "eval";
     case FUNCTION_SCOPE: return "function";
     case MODULE_SCOPE: return "module";
     case SCRIPT_SCOPE: return "global";
     case CATCH_SCOPE: return "catch";
     case BLOCK_SCOPE: return "block";
     case WITH_SCOPE: return "with";
     case ARROW_SCOPE: return "arrow";
+    case CLASS_SCOPE:
+      return "class";
   }
   UNREACHABLE();
   return NULL;
 }
 
 
 static void Indent(int n, const char* str) {
   PrintF("%*s%s", n, "", str);
 }
 
@@ skipping 252 matching lines @@
   // (functions and consts may be resolved by the parser).
   if (proxy->is_resolved()) return true;
 
   // Otherwise, try to resolve the variable.
   BindingKind binding_kind;
   Variable* var = LookupRecursive(proxy, &binding_kind, factory);
   switch (binding_kind) {
     case BOUND:
       // We found a variable binding.
       if (is_strong(language_mode())) {
-        // Check for declaration-after use (for variables) in strong mode. Note
-        // that we can only do this in the case where we have seen the
-        // declaration. And we always allow referencing functions (for now).
-
-        // If both the use and the declaration are inside an eval scope
-        // (possibly indirectly), or one of them is, we need to check whether
-        // they are inside the same eval scope or different
-        // ones.
-
-        // TODO(marja,rossberg): Detect errors across different evals (depends
-        // on the future of eval in strong mode).
-        const Scope* eval_for_use = NearestOuterEvalScope();
-        const Scope* eval_for_declaration =
-            var->scope()->NearestOuterEvalScope();
-
-        if (proxy->position() != RelocInfo::kNoPosition &&
-            proxy->position() < var->initializer_position() &&
-            !var->is_function() && eval_for_use == eval_for_declaration) {
-          DCHECK(proxy->end_position() != RelocInfo::kNoPosition);
-          ReportMessage(proxy->position(), proxy->end_position(),
-                        "strong_use_before_declaration", proxy->raw_name());
-          return false;
-        }
+        if (!CheckStrongModeDeclaration(proxy, var)) return false;
       }
       break;
 
     case BOUND_EVAL_SHADOWED:
       // We either found a variable binding that might be shadowed by eval  or
       // gave up on it (e.g. by encountering a local with the same in the outer
       // scope which was not promoted to a context, this can happen if we use
       // debugger to evaluate arbitrary expressions at a break point).
       if (var->IsGlobalObjectProperty()) {
         var = NonLocal(proxy->raw_name(), DYNAMIC_GLOBAL);
@@ skipping 24 matching lines @@
 
   DCHECK(var != NULL);
   if (proxy->is_assigned()) var->set_maybe_assigned();
 
   proxy->BindTo(var);
 
   return true;
 }
 
 
+bool Scope::CheckStrongModeDeclaration(VariableProxy* proxy, Variable* var) {
+  // Check for declaration-after use (for variables) in strong mode. Note that
+  // we can only do this in the case where we have seen the declaration. And we
+  // always allow referencing functions (for now).
+
+  // If both the use and the declaration are inside an eval scope (possibly
+  // indirectly), or one of them is, we need to check whether they are inside
+  // the same eval scope or different ones.
+
+  // TODO(marja,rossberg): Detect errors across different evals (depends on the
+  // future of eval in strong mode).
+  const Scope* eval_for_use = NearestOuterEvalScope();
+  const Scope* eval_for_declaration = var->scope()->NearestOuterEvalScope();
+
+  // Allow referencing the class name from methods, even though the initializer
+  // position for class names is only after the body. Note that the only
+  // variable declared in the class scope is the class name.
+  bool legal_class_name_reference = false;
+  if (var->scope()->is_class_scope()) {
+    // Referencing the class name is only allowed inside methods of that class.
+    Scope* scope = this;
+    bool found_method_scope = false;
+    while (scope && !found_method_scope && scope != var->scope()) {
+      if (scope->is_function_scope() && scope->outer_scope_ == var->scope()) {
+        found_method_scope = true;

[arv (Not doing code reviews), 2015/03/03 15:36:28]

It is still not clear why this is only matching the class name?

[marja, 2015/03/03 15:52:14]

This check only fires when we have resolved the VariableProxy against
*something* and then we reason that the *something* is a class name if it's
declared in the class scope. (The only declaration in that scope seems to be the
class name. (Empirically.))

+        break;
+      }
+      scope = scope->outer_scope();
+    }
+    legal_class_name_reference = found_method_scope;
+  }
+
+  if (proxy->position() != RelocInfo::kNoPosition &&
+      proxy->position() < var->initializer_position() && !var->is_function() &&
+      eval_for_use == eval_for_declaration && !legal_class_name_reference) {
+    DCHECK(proxy->end_position() != RelocInfo::kNoPosition);
+    ReportMessage(proxy->position(), proxy->end_position(),
+                  "strong_use_before_declaration", proxy->raw_name());
+    return false;
+  }
+  return true;
+}
+
+
 bool Scope::ResolveVariablesRecursively(CompilationInfo* info,
                                         AstNodeFactory* factory) {
   DCHECK(info->script_scope()->is_script_scope());
 
   // Resolve unresolved variables for this scope.
   for (int i = 0; i < unresolved_.length(); i++) {
     if (!ResolveVariable(info, unresolved_[i], factory)) return false;
   }
 
   // Resolve unresolved variables for inner scopes.
@@ skipping 44 matching lines @@
 }
 
 
 bool Scope::MustAllocate(Variable* var) {
   // Give var a read/write use if there is a chance it might be accessed
   // via an eval() call.  This is only possible if the variable has a
   // visible name.
   if ((var->is_this() || var->is_new_target() || !var->raw_name()->IsEmpty()) &&
       (var->has_forced_context_allocation() || scope_calls_eval_ ||
        inner_scope_calls_eval_ || scope_contains_with_ || is_catch_scope() ||
-       is_block_scope() || is_module_scope() || is_script_scope())) {
+       is_block_scope() || is_class_scope() || is_module_scope() ||
+       is_script_scope())) {
     var->set_is_used();
     if (scope_calls_eval_ || inner_scope_calls_eval_) var->set_maybe_assigned();
   }
   // Global variables do not need to be allocated.
   return !var->IsGlobalObjectProperty() && var->is_used();
 }
 
 
 bool Scope::MustAllocateInContext(Variable* var) {
   // If var is accessed from an inner scope, or if there is a possibility
   // that it might be accessed from the current or an inner scope (through
   // an eval() call or a runtime with lookup), it must be allocated in the
   // context.
   //
   // Exceptions: If the scope as a whole has forced context allocation, all
   // variables will have context allocation, even temporaries.  Otherwise
   // temporary variables are always stack-allocated.  Catch-bound variables are
   // always context-allocated.
   if (has_forced_context_allocation()) return true;
   if (var->mode() == TEMPORARY) return false;
   if (var->mode() == INTERNAL) return true;
-  if (is_catch_scope() || is_block_scope() || is_module_scope()) return true;
+  if (is_catch_scope() || is_block_scope() || is_class_scope() ||
+      is_module_scope()) {
+    return true;
+  }
   if (is_script_scope() && IsLexicalVariableMode(var->mode())) return true;
   return var->has_forced_context_allocation() ||
       scope_calls_eval_ ||
       inner_scope_calls_eval_ ||
       scope_contains_with_;
 }
 
 
 bool Scope::HasArgumentsParameter(Isolate* isolate) {
   for (int i = 0; i < params_.length(); i++) {
@@ skipping 188 matching lines @@
 }
 
 
 int Scope::ContextLocalCount() const {
   if (num_heap_slots() == 0) return 0;
   return num_heap_slots() - Context::MIN_CONTEXT_SLOTS -
       (function_ != NULL && function_->proxy()->var()->IsContextSlot() ? 1 : 0);
 }
 
 } }  // namespace v8::internal