Sloppy mode webcompat: allow conflicting function declarations in blocks

src/parsing/parser.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/parsing/parser.h"
 
 #include "src/api.h"
 #include "src/ast/ast.h"
 #include "src/ast/ast-expression-rewriter.h"
 #include "src/ast/ast-expression-visitor.h"
@@ skipping 1908 matching lines @@
 }
 
 
 Variable* Parser::Declare(Declaration* declaration,
                           DeclarationDescriptor::Kind declaration_kind,
                           bool resolve, bool* ok, Scope* scope) {
   VariableProxy* proxy = declaration->proxy();
   DCHECK(proxy->raw_name() != NULL);
   const AstRawString* name = proxy->raw_name();
   VariableMode mode = declaration->mode();
+  bool is_function_declaration = declaration->IsFunctionDeclaration();
   if (scope == nullptr) scope = scope_;
   Scope* declaration_scope =
       IsLexicalVariableMode(mode) ? scope : scope->DeclarationScope();
   Variable* var = NULL;
 
   // If a suitable scope exists, then we can statically declare this
   // variable and also set its mode. In any case, a Declaration node
   // will be added to the scope so that the declaration can be added
   // to the corresponding activation frame at runtime if necessary.
   // For instance, var declarations inside a sloppy eval scope need
   // to be added to the calling function context. Similarly, strict
   // mode eval scope and lexical eval bindings do not leak variable
   // declarations to the caller's scope so we declare all locals, too.
   if (declaration_scope->is_function_scope() ||
       declaration_scope->is_block_scope() ||
       declaration_scope->is_module_scope() ||
       declaration_scope->is_script_scope() ||
       (declaration_scope->is_eval_scope() &&
        (is_strict(declaration_scope->language_mode()) ||
         IsLexicalVariableMode(mode)))) {
     // Declare the variable in the declaration scope.
     var = declaration_scope->LookupLocal(name);
     if (var == NULL) {
       // Declare the name.
       Variable::Kind kind = Variable::NORMAL;
       int declaration_group_start = -1;
-      if (declaration->IsFunctionDeclaration()) {
+      if (is_function_declaration) {
         kind = Variable::FUNCTION;
       } else if (declaration->IsVariableDeclaration() &&
                  declaration->AsVariableDeclaration()->is_class_declaration()) {
         kind = Variable::CLASS;
         declaration_group_start =
             declaration->AsVariableDeclaration()->declaration_group_start();
       }
       var = declaration_scope->DeclareLocal(
           name, mode, declaration->initialization(), kind, kNotAssigned,
           declaration_group_start);
-    } else if (IsLexicalVariableMode(mode) ||
-               IsLexicalVariableMode(var->mode()) ||
+    } else if (((IsLexicalVariableMode(mode) ||
+                 IsLexicalVariableMode(var->mode())) &&
+                // Allow duplicate function decls for web compat, see bug 4693.
+                (is_strict(language_mode()) || !is_function_declaration ||
+                 !var->is_function())) ||
                ((mode == CONST_LEGACY || var->mode() == CONST_LEGACY) &&
                 !declaration_scope->is_script_scope())) {
       // The name was declared in this scope before; check for conflicting
       // re-declarations. We have a conflict if either of the declarations is
       // not a var (in script scope, we also have to ignore legacy const for
       // compatibility). There is similar code in runtime.cc in the Declare
       // functions. The function CheckConflictingVarDeclarations checks for
       // var and let bindings from different scopes whereas this is a check for
       // conflicting declarations within the same scope. This check also covers
       // the special case
@@ skipping 3751 matching lines @@
     auto class_literal = value->AsClassLiteral();
     if (class_literal->raw_name() == nullptr) {
       class_literal->set_raw_name(name);
     }
   }
 }
 
 
 }  // namespace internal
 }  // namespace v8