a === b -> identical(a, b)

sdk/lib/_internal/compiler/implementation/ssa/builder.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of ssa;
 
 class Interceptors {
   Compiler compiler;
   Interceptors(Compiler this.compiler);
 
@@ skipping 1283 matching lines @@
    */
   void buildFieldInitializers(ClassElement classElement,
                               Map<Element, HInstruction> fieldValues) {
     assert(invariant(classElement, classElement.isImplementation));
     classElement.forEachInstanceField(
         (ClassElement enclosingClass, Element member) {
           TreeElements definitions = compiler.analyzeElement(member);
           Node node = member.parseNode(compiler);
           SendSet assignment = node.asSendSet();
           HInstruction value;
-          if (assignment === null) {
+          if (assignment == null) {
             value = graph.addConstantNull(constantSystem);
           } else {
             Node right = assignment.arguments.head;
             TreeElements savedElements = elements;
             elements = definitions;
             right.accept(this);
             elements = savedElements;
             value = pop();
           }
           fieldValues[member] = value;
@@ skipping 138 matching lines @@
     Element checkResultElement =
         localsHandler.closureData.parametersWithSentinel[element];
     if (currentElement.isGenerativeConstructorBody()) {
       // A generative constructor body receives extra parameters that
       // indicate if a parameter was passed to the factory.
       check = addParameter(checkResultElement);
     } else {
       // This is the code we emit for a parameter that is being checked
       // on whether it was given at value at the call site:
       //
-      // foo([a = 42) {
+      // foo([a = 42]) {
       //   if (?a) print('parameter passed $a');
       // }
       //
       // foo([a = 42]) {
-      //   var t1 = a === sentinel;
+      //   var t1 = identical(a, sentinel);
       //   if (t1) a = 42;
       //   if (!t1) print('parameter passed ' + a);
       // }
 
       // Fetch the original default value of [element];
       ConstantHandler handler = compiler.constantHandler;
       Constant constant = handler.compileVariable(element);
       HConstant defaultValue = constant == null
           ? graph.addConstantNull(constantSystem)
           : graph.addConstant(constant);
@@ skipping 3281 matching lines @@
           new HSubGraphBlockInformation(elseBranch.graph));
 
     HBasicBlock conditionStartBlock = conditionBranch.block;
     conditionStartBlock.setBlockFlow(info, joinBlock);
     SubGraph conditionGraph = conditionBranch.graph;
     HIf branch = conditionGraph.end.last;
     assert(branch is HIf);
     branch.blockInformation = conditionStartBlock.blockFlow;
   }
 }