Don't skip hole checks inside patterns in parameter lists

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 <memory>
 
 #include "src/api.h"
 #include "src/ast/ast-expression-rewriter.h"
@@ skipping 2921 matching lines @@
     descriptor.scope = scope();
     descriptor.hoist_scope = nullptr;
     descriptor.mode = LET;
     descriptor.declaration_pos = parameter.pattern->position();
     // The position that will be used by the AssignmentExpression
     // which copies from the temp parameter to the pattern.
     //
     // TODO(adamk): Should this be kNoSourcePosition, since
     // it's just copying from a temp var to the real param var?
     descriptor.initialization_pos = parameter.pattern->position();
-    // The initializer position which will end up in,
-    // Variable::initializer_position(), used for hole check elimination.
-    int initializer_position = parameter.pattern->position();
     Expression* initial_value =
         factory()->NewVariableProxy(parameters.scope->parameter(i));
     if (parameter.initializer != nullptr) {
       // IS_UNDEFINED($param) ? initializer : $param
 
       // Ensure initializer is rewritten
       RewriteParameterInitializer(parameter.initializer, scope());
 
       auto condition = factory()->NewCompareOperation(
           Token::EQ_STRICT,
           factory()->NewVariableProxy(parameters.scope->parameter(i)),
           factory()->NewUndefinedLiteral(kNoSourcePosition), kNoSourcePosition);
       initial_value = factory()->NewConditional(
           condition, parameter.initializer, initial_value, kNoSourcePosition);
       descriptor.initialization_pos = parameter.initializer->position();
-      initializer_position = parameter.initializer_end_position;
     }
 
     Scope* param_scope = scope();
     Block* param_block = init_block;
     if (!parameter.is_simple() && scope()->calls_sloppy_eval()) {
       param_scope = NewVarblockScope();
       param_scope->set_start_position(descriptor.initialization_pos);
       param_scope->set_end_position(parameter.initializer_end_position);
       param_scope->RecordEvalCall();
       param_block = factory()->NewBlock(NULL, 8, true, kNoSourcePosition);
       param_block->set_scope(param_scope);
       descriptor.hoist_scope = scope();
       // Pass the appropriate scope in so that PatternRewriter can appropriately
       // rewrite inner initializers of the pattern to param_scope
       descriptor.scope = param_scope;
       // Rewrite the outer initializer to point to param_scope
       ReparentParameterExpressionScope(stack_limit(), initial_value,
                                        param_scope);
     }
 
     BlockState block_state(&scope_state_, param_scope);
     DeclarationParsingResult::Declaration decl(
-        parameter.pattern, initializer_position, initial_value);
+        parameter.pattern, parameter.initializer_end_position, initial_value);
     PatternRewriter::DeclareAndInitializeVariables(
         this, param_block, &descriptor, &decl, nullptr, CHECK_OK);
 
     if (param_block != init_block) {
       param_scope = block_state.FinalizedBlockScope();
       if (param_scope != nullptr) {
         CheckConflictingVarDeclarations(param_scope, CHECK_OK);
       }
       init_block->statements()->Add(param_block, zone());
     }
@@ skipping 2452 matching lines @@
 
   return final_loop;
 }
 
 #undef CHECK_OK
 #undef CHECK_OK_VOID
 #undef CHECK_FAILED
 
 }  // namespace internal
 }  // namespace v8