PreParser scope analysis: sloppy block funcs.

src/parsing/parser-base.h

 // 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.
 
 #ifndef V8_PARSING_PARSER_BASE_H
 #define V8_PARSING_PARSER_BASE_H
 
 #include "src/ast/ast.h"
 #include "src/ast/scopes.h"
 #include "src/bailout-reason.h"
@@ skipping 3762 matching lines @@
   FuncNameInferrer::State fni_state(fni_);
   impl()->PushEnclosingName(name);
   FunctionLiteralT function = impl()->ParseFunctionLiteral(
       name, scanner()->location(), name_validity,
       is_generator ? FunctionKind::kGeneratorFunction
                    : is_async ? FunctionKind::kAsyncFunction
                               : FunctionKind::kNormalFunction,
       pos, FunctionLiteral::kDeclaration, language_mode(),
       CHECK_OK_CUSTOM(NullStatement));
 
-  return impl()->DeclareFunction(variable_name, function, pos, is_generator,
-                                 is_async, names, ok);
+  // In ES6, a function behaves as a lexical binding, except in
+  // a script scope, or the initial scope of eval or another function.
+  VariableMode mode =
+      (!scope()->is_declaration_scope() || scope()->is_module_scope()) ? LET
+                                                                       : VAR;
+  // Async functions don't undergo sloppy mode block scoped hoisting, and don't
+  // allow duplicates in a block. Both are represented by the
+  // sloppy_block_function_map. Don't add them to the map for async functions.
+  // Generators are also supposed to be prohibited; currently doing this behind
+  // a flag and UseCounting violations to assess web compatibility.
+  bool is_sloppy_block_function =
+      is_sloppy(language_mode()) && !scope()->is_declaration_scope() &&
+      !is_async && !(allow_harmony_restrictive_generators() && is_generator);
+
+  return impl()->DeclareFunction(variable_name, function, mode, pos,
+                                 is_generator, is_async,
+                                 is_sloppy_block_function, names, ok);
 }
 
 template <typename Impl>
 typename ParserBase<Impl>::StatementT ParserBase<Impl>::ParseClassDeclaration(
     ZoneList<const AstRawString*>* names, bool default_export, bool* ok) {
   // ClassDeclaration ::
   //   'class' Identifier ('extends' LeftHandExpression)? '{' ClassBody '}'
   //   'class' ('extends' LeftHandExpression)? '{' ClassBody '}'
   //
   // The anonymous form is allowed iff [default_export] is true.
@@ skipping 1734 matching lines @@
     has_seen_constructor_ = true;
     return;
   }
 }
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_PARSING_PARSER_BASE_H