Analyzer: Support const Symbol('>>>')

Bug: #44908
Change-Id: I7af5587317da43f79f043dd7e92976e1011935ca
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/185242
Reviewed-by: Brian Wilkerson <[email protected]>
Reviewed-by: Konstantin Shcheglov <[email protected]>
Commit-Queue: Samuel Rawlins <[email protected]>

Author: srawlins

pkg/analyzer/lib/src/dart/constant/compute.dart

@@ -77,7 +77,8 @@ class _ConstantWalker extends graph.DependencyWalker<_ConstantNode> {
   }
 
   ConstantEvaluationEngine _getEvaluationEngine(_ConstantNode node) {
-    return ConstantEvaluationEngine(declaredVariables);
+    return ConstantEvaluationEngine(
+        declaredVariables, experimentStatus.triple_shift);
   }
 
   _ConstantNode _getNode(ConstantEvaluationTarget constant) {

pkg/analyzer/lib/src/dart/constant/constant_verifier.dart

@@ -3,6 +3,7 @@
 // BSD-style license that can be found in the LICENSE file.
 
 import 'package:analyzer/dart/analysis/declared_variables.dart';
+import 'package:analyzer/dart/analysis/features.dart';
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/token.dart';
 import 'package:analyzer/dart/ast/visitor.dart';
@@ -65,7 +66,8 @@ class ConstantVerifier extends RecursiveAstVisitor<void> {
     this._typeSystem,
     this._typeProvider,
     this.declaredVariables,
-  ) : _evaluationEngine = ConstantEvaluationEngine(declaredVariables);
+  ) : _evaluationEngine = ConstantEvaluationEngine(declaredVariables,
+            _currentLibrary.featureSet.isEnabled(Feature.triple_shift));
 
   bool get _isNonNullableByDefault => _currentLibrary.isNonNullableByDefault;
 

pkg/analyzer/lib/src/dart/constant/evaluation.dart

@@ -58,11 +58,15 @@ class ConstantEvaluationEngine {
   /// The set of variables declared on the command line using '-D'.
   final DeclaredVariables _declaredVariables;
 
+  /// Whether the `triple_shift` experiment is enabled.
+  final bool _isTripleShiftExperimentEnabled;
+
   /// Initialize a newly created [ConstantEvaluationEngine].
   ///
   /// [declaredVariables] is the set of variables declared on the command
   /// line using '-D'.
-  ConstantEvaluationEngine(DeclaredVariables declaredVariables)
+  ConstantEvaluationEngine(
+      DeclaredVariables declaredVariables, this._isTripleShiftExperimentEnabled)
       : _declaredVariables = declaredVariables;
 
   /// Check that the arguments to a call to fromEnvironment() are correct. The
@@ -127,7 +131,14 @@ class ConstantEvaluationEngine {
       return false;
     }
     var name = argumentValues[0]?.toStringValue();
-    return name != null && isValidPublicSymbol(name);
+    if (name == null) {
+      return false;
+    }
+    // TODO(srawlins): If the argument is '>>>' but triple-shift is not enabled,
+    // report a different error indicating that the triple-shift experiment
+    // should be enabled, or a minimum SDK version set, when one is declared.
+    return isValidPublicSymbol(name) ||
+        (_isTripleShiftExperimentEnabled && name == '>>>');
   }
 
   /// Compute the constant value associated with the given [constant].
@@ -414,11 +425,11 @@ class ConstantEvaluationEngine {
 
     constructor = followConstantRedirectionChain(constructor);
     InterfaceType definingType = constructor.returnType;
-    ClassElement definingClass = constructor.enclosingElement;
     if (constructor.isFactory) {
       // We couldn't find a non-factory constructor.
       // See if it's because we reached an external const factory constructor
       // that we can emulate.
+      ClassElement definingClass = constructor.enclosingElement;
       if (constructor.name == "fromEnvironment") {
         if (!checkFromEnvironmentArguments(
             library, arguments, argumentValues, namedValues, definingType)) {
@@ -479,8 +490,6 @@ class ConstantEvaluationEngine {
         definingType,
       );
     }
-    var constructorBase = constructor.declaration as ConstructorElementImpl;
-    var initializers = constructorBase.constantInitializers;
 
     var fieldMap = HashMap<String, DartObjectImpl>();
 
@@ -597,6 +606,8 @@ class ConstantEvaluationEngine {
       lexicalEnvironment: parameterMap,
       substitution: Substitution.fromInterfaceType(definingType),
     );
+    var constructorBase = constructor.declaration as ConstructorElementImpl;
+    var initializers = constructorBase.constantInitializers;
     String? superName;
     NodeList<Expression>? superArguments;
     for (var i = 0; i < initializers.length; i++) {

pkg/analyzer/lib/src/dart/constant/value.dart

@@ -1676,8 +1676,8 @@ abstract class InstanceState {
     return BoolState.from(leftValue | rightValue);
   }
 
-  /// Return the result of invoking the '>>' operator on this object with
-  /// the [rightOperand].
+  /// Return the result of invoking the '>>>' operator on this object
+  /// with the [rightOperand].
   ///
   /// Throws an [EvaluationException] if the operator is not appropriate for an
   /// object of this kind.

pkg/analyzer/lib/src/generated/constant.dart

@@ -3,6 +3,7 @@
 // BSD-style license that can be found in the LICENSE file.
 
 import 'package:analyzer/dart/analysis/declared_variables.dart';
+import 'package:analyzer/dart/analysis/features.dart';
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/error/error.dart';
 import 'package:analyzer/error/listener.dart';
@@ -113,6 +114,7 @@ class ConstantEvaluator {
     var result = expression.accept(ConstantVisitor(
         ConstantEvaluationEngine(
           DeclaredVariables(),
+          _library.featureSet.isEnabled(Feature.triple_shift),
         ),
         _library,
         errorReporter));

pkg/analyzer/lib/src/lint/linter.dart

@@ -369,7 +369,8 @@ class LinterContextImpl implements LinterContext {
     );
 
     var visitor = ConstantVisitor(
-      ConstantEvaluationEngine(declaredVariables),
+      ConstantEvaluationEngine(
+          declaredVariables, isEnabled(Feature.triple_shift)),
       libraryElement,
       errorReporter,
     );

pkg/analyzer/test/src/dart/constant/evaluation_test.dart

@@ -2,6 +2,7 @@
 // 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.
 
+import 'package:analyzer/dart/analysis/features.dart';
 import 'package:analyzer/error/error.dart';
 import 'package:analyzer/error/listener.dart';
 import 'package:analyzer/src/dart/analysis/experiments.dart';
@@ -1042,7 +1043,11 @@ class ConstantVisitorTestSupport extends PubPackageResolutionTest
   }) {
     var expression = findNode.topVariableDeclarationByName(name).initializer!;
 
-    var source = this.result.unit!.declaredElement!.source;
+    var unit = this.result.unit;
+    if (unit == null) {
+      throw StateError('analysis result unit is null');
+    }
+    var source = unit.declaredElement!.source;
     var errorListener = GatheringErrorListener();
     var errorReporter = ErrorReporter(
       errorListener,
@@ -1054,6 +1059,7 @@ class ConstantVisitorTestSupport extends PubPackageResolutionTest
       ConstantVisitor(
         ConstantEvaluationEngine(
           DeclaredVariables.fromMap(declaredVariables),
+          unit.featureSet.isEnabled(Feature.triple_shift),
         ),
         this.result.libraryElement as LibraryElementImpl,
         errorReporter,