[CFE] Expression evaluation: Use dynamic get etc and fixup names to access private stuff when possible

For expression evaluation we want to be "more than dart" in that if for
instance we can see (in the debugger) that a List contains `B`s (even
if it's typed as containing `A`s) we'd like to be able to access things
on `B` (without manually having to cast to either `B` or `dynamic`).

Furthermore - when we in the debugger can see that it's a `B`, and that
`B` has, say, a field `_privateField` or a method `_privateMethod` we'd
like to be able to access that even if `B` is in another library.

This CL - for expression evaluation - makes dynamic accesses and calls
where we would normally issue a "missing getter" (etc) error, and tries
to create a `Name` so private access is possible.

Change-Id: I887318a50413e9a5f11ec685b27719edd312dca0
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/446260
Reviewed-by: Alexander Markov <[email protected]>
Commit-Queue: Jens Johansen <[email protected]>
Reviewed-by: Nicholas Shahan <[email protected]>

Author: jensjoha

pkg/dev_compiler/test/expression_compiler/expression_compiler_e2e_shared.dart

@@ -1066,8 +1066,10 @@ void runAgnosticSharedTestsShard1(
           breakpointId: 'innerScopeBP',
           expression: 'notInScope',
           expectedError:
-              "Error: The getter 'notInScope' isn't defined for the"
-              " type 'C'.",
+              "DartError: NoSuchMethodError: 'notInScope'\n"
+              'method not found\n'
+              "Receiver: Instance of 'C'\n"
+              'Arguments: []\n',
         );
       });
 
@@ -1076,8 +1078,10 @@ void runAgnosticSharedTestsShard1(
           breakpointId: 'innerScopeBP',
           expression: 'innerNotInScope',
           expectedError:
-              "Error: The getter 'innerNotInScope' isn't defined for the"
-              " type 'C'.",
+              "DartError: NoSuchMethodError: 'innerNotInScope'\n"
+              'method not found\n'
+              "Receiver: Instance of 'C'\n"
+              'Arguments: []\n',
         );
       });
     });
@@ -1105,7 +1109,11 @@ void runAgnosticSharedTestsShard1(
         await driver.checkInFrame(
           breakpointId: 'parseIntPlusOneBP',
           expression: 'typo',
-          expectedError: "Error: The getter 'typo' isn't defined",
+          expectedError:
+              "DartError: NoSuchMethodError: 'typo'\n"
+              'method not found\n'
+              'Receiver: "1234"\n'
+              'Arguments: []\n',
         );
       });
 
@@ -1183,7 +1191,11 @@ void runAgnosticSharedTestsShard1(
         await driver.checkInFrame(
           breakpointId: 'methodBP',
           expression: 'typo',
-          expectedError: "The getter 'typo' isn't defined for the type 'C'",
+          expectedError:
+              "DartError: NoSuchMethodError: 'typo'\n"
+              'method not found\n'
+              "Receiver: Instance of 'C'\n"
+              'Arguments: []\n',
         );
       });
 
@@ -1510,7 +1522,11 @@ void runAgnosticSharedTestsShard2(
         await driver.checkInFrame(
           breakpointId: 'constructorBP',
           expression: 'typo',
-          expectedError: "The getter 'typo' isn't defined for the type 'C'",
+          expectedError:
+              "DartError: NoSuchMethodError: 'typo'\n"
+              'method not found\n'
+              "Receiver: Instance of 'C'\n"
+              'Arguments: []\n',
         );
       });
 
@@ -1645,7 +1661,11 @@ void runAgnosticSharedTestsShard2(
         await driver.checkInFrame(
           breakpointId: 'asyncTestBP1',
           expression: 'typo',
-          expectedError: "The getter 'typo' isn't defined for the type 'D'",
+          expectedError:
+              "DartError: NoSuchMethodError: 'typo'\n"
+              'method not found\n'
+              "Receiver: Instance of 'D'\n"
+              'Arguments: []\n',
         );
       });
 

pkg/front_end/lib/src/base/incremental_compiler.dart

@@ -10,6 +10,7 @@ import 'package:_fe_analyzer_shared/src/scanner/abstract_scanner.dart'
     show ScannerConfiguration;
 import 'package:front_end/src/base/name_space.dart';
 import 'package:front_end/src/type_inference/inference_results.dart';
+import 'package:front_end/src/type_inference/object_access_target.dart';
 import 'package:kernel/binary/ast_from_binary.dart'
     show
         BinaryBuilderWithMetadata,
@@ -20,7 +21,7 @@ import 'package:kernel/binary/ast_from_binary.dart'
 import 'package:kernel/canonical_name.dart'
     show CanonicalNameError, CanonicalNameSdkError;
 import 'package:kernel/class_hierarchy.dart'
-    show ClassHierarchy, ClosedWorldClassHierarchy;
+    show ClassHierarchy, ClassHierarchySubtypes, ClosedWorldClassHierarchy;
 import 'package:kernel/dart_scope_calculator.dart'
     show DartScope, DartScopeBuilder2;
 import 'package:kernel/kernel.dart'
@@ -35,6 +36,7 @@ import 'package:kernel/kernel.dart'
         ExtensionType,
         ExtensionTypeDeclaration,
         FunctionNode,
+        InterfaceType,
         Library,
         LibraryDependency,
         LibraryPart,
@@ -50,10 +52,11 @@ import 'package:kernel/kernel.dart'
         TreeNode,
         TypeParameter,
         VariableDeclaration,
+        VariableGet,
+        VariableSet,
         VisitorDefault,
         VisitorVoidMixin,
-        VariableGet,
-        VariableSet;
+        Member;
 import 'package:kernel/kernel.dart' as kernel show Combinator;
 import 'package:kernel/reference_from_index.dart';
 import 'package:kernel/target/changed_structure_notifier.dart'
@@ -92,7 +95,7 @@ import '../source/source_library_builder.dart'
 import '../source/source_loader.dart';
 import '../type_inference/inference_helper.dart' show InferenceHelper;
 import '../type_inference/inference_visitor.dart'
-    show ExpressionEvaluationHelper;
+    show ExpressionEvaluationHelper, OverwrittenInterfaceMember;
 import '../util/error_reporter_file_copier.dart' show saveAsGzip;
 import '../util/experiment_environment_getter.dart'
     show enableIncrementalCompilerBenchmarking, getExperimentEnvironment;
@@ -1953,8 +1956,10 @@ class IncrementalCompiler implements IncrementalKernelGenerator {
           new Name(syntheticProcedureName), ProcedureKind.Method, parameters,
           isStatic: isStatic, fileUri: debugLibrary.fileUri);
 
+      ClassHierarchy hierarchy = lastGoodKernelTarget.loader.hierarchy;
+
       ExpressionEvaluationHelper expressionEvaluationHelper =
-          new ExpressionEvaluationHelperImpl(extraKnownVariables);
+          new ExpressionEvaluationHelperImpl(extraKnownVariables, hierarchy);
 
       Expression compiledExpression = await lastGoodKernelTarget.loader
           .buildExpression(
@@ -2188,8 +2193,10 @@ class IncrementalCompiler implements IncrementalKernelGenerator {
 // Coverage-ignore(suite): Not run.
 class ExpressionEvaluationHelperImpl implements ExpressionEvaluationHelper {
   final Set<VariableDeclarationImpl> knownButUnavailable = {};
+  final ClassHierarchy hierarchy;
 
-  ExpressionEvaluationHelperImpl(List<VariableDeclarationImpl> extraKnown) {
+  ExpressionEvaluationHelperImpl(
+      List<VariableDeclarationImpl> extraKnown, this.hierarchy) {
     for (VariableDeclarationImpl variable in extraKnown) {
       if (variable.isConst) {
         // We allow const variables - these are inlined (we check
@@ -2232,6 +2239,47 @@ class ExpressionEvaluationHelperImpl implements ExpressionEvaluationHelper {
           includeExpression: false,
         ));
   }
+
+  @override
+  OverwrittenInterfaceMember? overwriteFindInterfaceMember({
+    required ObjectAccessTarget target,
+    required DartType receiverType,
+    required Name name,
+  }) {
+    // On a missing target, rewrite to a dynamic target instead.
+    if (target.kind == ObjectAccessTargetKind.missing) {
+      // On a private name, try to find a descendant of receiverType
+      // that has the name.
+      ClassHierarchy hierarchy = this.hierarchy;
+      if (name.isPrivate &&
+          receiverType is InterfaceType &&
+          hierarchy is ClosedWorldClassHierarchy) {
+        // Find all libraries that contains a subtype of this type with a
+        // textually matching name.
+        ClassHierarchySubtypes subtypeInformation =
+            hierarchy.computeSubtypesInformation();
+        Set<Library> foundMatchInLibrary = {};
+        for (Class cls
+            in subtypeInformation.getSubtypesOf(receiverType.classNode)) {
+          for (Member member in cls.members) {
+            if (member.name.text == name.text) {
+              foundMatchInLibrary.add(cls.enclosingLibrary);
+              break;
+            }
+          }
+        }
+        // If we only found one such library we overwrite the name so the VM
+        // will mangle the names right and find the wanted target.
+        if (foundMatchInLibrary.length == 1 &&
+            name.library != foundMatchInLibrary.first) {
+          name = new Name(name.text, foundMatchInLibrary.first);
+        }
+      }
+      return new OverwrittenInterfaceMember(
+          target: const ObjectAccessTarget.dynamic(), name: name);
+    }
+    return null;
+  }
 }
 
 // Coverage-ignore(suite): Not run.

pkg/front_end/lib/src/type_inference/inference_visitor.dart

@@ -72,7 +72,6 @@ import 'shared_type_analyzer.dart';
 import 'stack_values.dart';
 import 'type_constraint_gatherer.dart';
 import 'type_inference_engine.dart';
-import 'type_inferrer.dart' show TypeInferrerImpl;
 import 'type_schema.dart' show UnknownType, isKnown;
 
 abstract class InferenceVisitor {
@@ -174,18 +173,13 @@ class InferenceVisitorImpl extends InferenceVisitorBase
   // variable was declared outside the try statement or local function.
   bool _inTryOrLocalFunction = false;
 
-  /// Helper used to issue correct error messages and avoid access to
-  /// unavailable variables upon expression evaluation.
-  final ExpressionEvaluationHelper? expressionEvaluationHelper;
-
   InferenceVisitorImpl(
-      TypeInferrerImpl inferrer,
-      InferenceHelper helper,
+      super.inferrer,
+      super.helper,
       this._constructorBuilder,
       this.operations,
       this.typeAnalyzerOptions,
-      this.expressionEvaluationHelper)
-      : super(inferrer, helper);
+      super.expressionEvaluationHelper);
 
   @override
   int get stackHeight => _rewriteStack.length;
@@ -7292,6 +7286,16 @@ class InferenceVisitorImpl extends InferenceVisitorBase
         leftType, binaryName, fileOffset,
         includeExtensionMethods: true, isSetter: false);
 
+    if (expressionEvaluationHelper != null) {
+      // Coverage-ignore-block(suite): Not run.
+      OverwrittenInterfaceMember? overWritten =
+          expressionEvaluationHelper?.overwriteFindInterfaceMember(
+              target: binaryTarget, name: binaryName, receiverType: leftType);
+      if (overWritten != null) {
+        binaryTarget = overWritten.target;
+      }
+    }
+
     MethodContravarianceCheckKind binaryCheckKind =
         preCheckInvocationContravariance(leftType, binaryTarget,
             isThisReceiver: false);
@@ -7462,6 +7466,18 @@ class InferenceVisitorImpl extends InferenceVisitorBase
         expressionType, unaryName, fileOffset,
         includeExtensionMethods: true, isSetter: false);
 
+    if (expressionEvaluationHelper != null) {
+      // Coverage-ignore-block(suite): Not run.
+      OverwrittenInterfaceMember? overWritten =
+          expressionEvaluationHelper?.overwriteFindInterfaceMember(
+              target: unaryTarget,
+              name: unaryName,
+              receiverType: expressionType);
+      if (overWritten != null) {
+        unaryTarget = overWritten.target;
+      }
+    }
+
     MethodContravarianceCheckKind unaryCheckKind =
         preCheckInvocationContravariance(expressionType, unaryTarget,
             isThisReceiver: false);
@@ -7589,6 +7605,17 @@ class InferenceVisitorImpl extends InferenceVisitorBase
       Expression readIndex,
       DartType indexType,
       MethodContravarianceCheckKind readCheckKind) {
+    if (expressionEvaluationHelper != null) {
+      // Coverage-ignore-block(suite): Not run.
+      OverwrittenInterfaceMember? overWritten =
+          expressionEvaluationHelper?.overwriteFindInterfaceMember(
+              target: readTarget,
+              name: indexGetName,
+              receiverType: receiverType);
+      if (overWritten != null) {
+        readTarget = overWritten.target;
+      }
+    }
     Expression read;
     DartType readType = readTarget.getReturnType(this);
     switch (readTarget.kind) {
@@ -7731,6 +7758,17 @@ class InferenceVisitorImpl extends InferenceVisitorBase
       DartType indexType,
       Expression value,
       DartType valueType) {
+    if (expressionEvaluationHelper != null) {
+      // Coverage-ignore-block(suite): Not run.
+      OverwrittenInterfaceMember? overWritten =
+          expressionEvaluationHelper?.overwriteFindInterfaceMember(
+              target: writeTarget,
+              name: indexSetName,
+              receiverType: receiverType);
+      if (overWritten != null) {
+        writeTarget = overWritten.target;
+      }
+    }
     Expression write;
     switch (writeTarget.kind) {
       case ObjectAccessTargetKind.missing:
@@ -7902,6 +7940,18 @@ class InferenceVisitorImpl extends InferenceVisitorBase
       Expression value,
       {required DartType valueType,
       required bool forEffect}) {
+    if (expressionEvaluationHelper != null) {
+      // Coverage-ignore-block(suite): Not run.
+      OverwrittenInterfaceMember? overWritten =
+          expressionEvaluationHelper?.overwriteFindInterfaceMember(
+              target: writeTarget,
+              name: propertyName,
+              receiverType: receiverType);
+      if (overWritten != null) {
+        writeTarget = overWritten.target;
+        propertyName = overWritten.name;
+      }
+    }
     Expression write;
     DartType writeType = valueType;
     switch (writeTarget.kind) {
@@ -12824,4 +12874,18 @@ abstract class ExpressionEvaluationHelper {
 
   ExpressionInferenceResult? visitVariableSet(
       VariableSet node, DartType typeContext, InferenceHelper helper);
+
+  OverwrittenInterfaceMember? overwriteFindInterfaceMember({
+    required ObjectAccessTarget target,
+    required DartType receiverType,
+    required Name name,
+  });
+}
+
+// Coverage-ignore(suite): Not run.
+class OverwrittenInterfaceMember {
+  final ObjectAccessTarget target;
+  final Name name;
+
+  OverwrittenInterfaceMember({required this.target, required this.name});
 }

pkg/front_end/lib/src/type_inference/inference_visitor_base.dart

@@ -141,7 +141,12 @@ abstract class InferenceVisitorBase implements InferenceVisitor {
 
   final InferenceHelper _helper;
 
-  InferenceVisitorBase(this._inferrer, this._helper);
+  /// Helper used to issue correct error messages and avoid access to
+  /// unavailable variables upon expression evaluation.
+  final ExpressionEvaluationHelper? expressionEvaluationHelper;
+
+  InferenceVisitorBase(
+      this._inferrer, this._helper, this.expressionEvaluationHelper);
 
   AssignedVariables<TreeNode, VariableDeclaration> get assignedVariables =>
       _inferrer.assignedVariables;
@@ -3797,6 +3802,17 @@ abstract class InferenceVisitorBase implements InferenceVisitor {
       isSetter: false,
     );
 
+    if (expressionEvaluationHelper != null) {
+      // Coverage-ignore-block(suite): Not run.
+      OverwrittenInterfaceMember? overWritten =
+          expressionEvaluationHelper?.overwriteFindInterfaceMember(
+              target: target, name: name, receiverType: receiverType);
+      if (overWritten != null) {
+        target = overWritten.target;
+        name = overWritten.name;
+      }
+    }
+
     switch (target.kind) {
       case ObjectAccessTargetKind.instanceMember:
       case ObjectAccessTargetKind.objectMember:
@@ -4840,6 +4856,20 @@ abstract class InferenceVisitorBase implements InferenceVisitor {
       includeExtensionMethods: true,
       isSetter: false,
     );
+
+    if (expressionEvaluationHelper != null) {
+      // Coverage-ignore-block(suite): Not run.
+      OverwrittenInterfaceMember? overWritten =
+          expressionEvaluationHelper?.overwriteFindInterfaceMember(
+              target: readTarget,
+              name: propertyName,
+              receiverType: receiverType);
+      if (overWritten != null) {
+        readTarget = overWritten.target;
+        propertyName = overWritten.name;
+      }
+    }
+
     // Coverage-ignore(suite): Not run.
     readType ??= readTarget.getGetterType(this);