[stable] [_fe_analyzer_shared] Handle private names in exhaustiveness…

… checking

Closes #52041

Cherry-pick: https://dart-review.googlesource.com/c/sdk/+/297462
Change-Id: I2bc2fc8fb38b30eb5e9c6e639c2603a5508dfec1
Fixes: #52254
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/302845
Reviewed-by: Johnni Winther <johnniwinther@google.com>
Commit-Queue: Paul Berry <paulberry@google.com>

pkg/_fe_analyzer_shared/test/exhaustiveness/data/issue52041.dart

@@ -0,0 +1,28 @@
+// Copyright (c) 2023, 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.
+
+sealed class B {}
+
+class C extends B {
+  final int _i;
+
+  C(this._i);
+}
+
+f(B b) {
+  /*
+   checkingOrder={B,C},
+   fields={_i:-},
+   subtypes={C},
+   type=B
+  */
+  switch (b) {
+    /*space=C(_i: int)*/ case C(:var _i):
+      print('C($_i)');
+  }
+}
+
+main() {
+  f(C(0));
+}

pkg/_fe_analyzer_shared/test/exhaustiveness/data/private/main.dart

@@ -0,0 +1,40 @@
+// Copyright (c) 2023, 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.
+
+import 'main_lib.dart';
+
+class A {
+  num get _a => 42
+  int get _b => 42;
+}
+
+class C extends B {
+}
+
+exhaustiveA(A a) => /*
+ fields={_a:num},
+ type=A
+*/switch (a) { A(: num _a) /*space=A(_a: num)*/=> 0, }
+
+nonExhaustiveA(A a) => /*
+ error=non-exhaustive:A(_a: double()),
+ fields={_a:num},
+ type=A
+*/switch (a) { A(: int _a) /*space=A(_a: int)*/=> 0, }
+
+exhaustiveB(B b) => /*
+ fields={_b:int},
+ type=B
+*/switch (b) { B(: int _b) /*space=B(_b: int)*/=> 0, }
+
+exhaustiveC(C c) => /*
+ fields={_a:num},
+ type=C
+*/switch (c) { C(: num _a) /*space=C(_a: num)*/=> 0, }
+
+nonExhaustiveA(C c) => /*analyzer.
+ error=non-exhaustive:C(_a: double()),
+ fields={_a:num},
+ type=C
+*/switch (c) { C(: int _a) /*analyzer.space=C(_a: int)*/=> 0, }

pkg/_fe_analyzer_shared/test/exhaustiveness/data/private/main_lib.dart

@@ -0,0 +1,10 @@
+// Copyright (c) 2023, 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.
+
+import 'main.dart';
+
+class B extends A {
+  int get _a => 42;
+  num get _b => 42;
+}

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

@@ -94,7 +94,8 @@ class ConstantVerifier extends RecursiveAstVisitor<void> {
               _currentLibrary.featureSet.isEnabled(Feature.non_nullable),
           configuration: ConstantEvaluationConfiguration(),
         ),
-        _exhaustivenessCache = AnalyzerExhaustivenessCache(_typeSystem) {
+        _exhaustivenessCache =
+            AnalyzerExhaustivenessCache(_typeSystem, _currentLibrary) {
     exhaustivenessDataForTesting = retainDataForTesting
         ? ExhaustivenessDataForTesting(_exhaustivenessCache)
         : null;

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

@@ -65,9 +65,9 @@ class AnalyzerExhaustivenessCache extends ExhaustivenessCache<DartType,
     InterfaceElement, EnumElement, FieldElement, DartObject> {
   final TypeSystemImpl typeSystem;
 
-  AnalyzerExhaustivenessCache(this.typeSystem)
+  AnalyzerExhaustivenessCache(this.typeSystem, LibraryElement enclosingLibrary)
       : super(
-            AnalyzerTypeOperations(typeSystem),
+            AnalyzerTypeOperations(typeSystem, enclosingLibrary),
             const AnalyzerEnumOperations(),
             AnalyzerSealedClassOperations(typeSystem));
 }
@@ -165,10 +165,11 @@ class AnalyzerSealedClassOperations
 
 class AnalyzerTypeOperations implements TypeOperations<DartType> {
   final TypeSystemImpl _typeSystem;
+  final LibraryElement _enclosingLibrary;
 
   final Map<InterfaceType, Map<Key, DartType>> _interfaceFieldTypesCaches = {};
 
-  AnalyzerTypeOperations(this._typeSystem);
+  AnalyzerTypeOperations(this._typeSystem, this._enclosingLibrary);
 
   @override
   DartType get boolType => _typeSystem.typeProvider.boolType;
@@ -322,11 +323,17 @@ class AnalyzerTypeOperations implements TypeOperations<DartType> {
         fieldTypes.addAll(_getInterfaceFieldTypes(supertype));
       }
       for (PropertyAccessorElement accessor in type.accessors) {
+        if (accessor.isPrivate && accessor.library != _enclosingLibrary) {
+          continue;
+        }
         if (accessor.isGetter && !accessor.isStatic) {
           fieldTypes[NameKey(accessor.name)] = accessor.type.returnType;
         }
       }
       for (MethodElement method in type.methods) {
+        if (method.isPrivate && method.library != _enclosingLibrary) {
+          continue;
+        }
         if (!method.isStatic) {
           fieldTypes[NameKey(method.name)] = method.type;
         }

pkg/front_end/lib/src/fasta/kernel/constant_evaluator.dart

@@ -399,11 +399,11 @@ class ConstantsTransformer extends RemovingTransformer {
   final bool errorOnUnevaluatedConstant;
   final bool isLateLocalLoweringEnabled;
 
-  /// Cache used for checking exhaustiveness.
-  late final CfeExhaustivenessCache exhaustivenessCache;
-
   final ExhaustivenessDataForTesting? _exhaustivenessDataForTesting;
 
+  /// Cache used for checking exhaustiveness.
+  CfeExhaustivenessCache? _exhaustivenessCache;
+
   ConstantsTransformer(
       Target target,
       Map<String, String>? environmentDefines,
@@ -431,9 +431,7 @@ class ConstantsTransformer extends RemovingTransformer {
             enableConstFunctions: enableConstFunctions,
             errorOnUnevaluatedConstant: errorOnUnevaluatedConstant,
             evaluationMode: evaluationMode),
-        _exhaustivenessDataForTesting = exhaustivenessDataForTesting {
-    exhaustivenessCache = new CfeExhaustivenessCache(constantEvaluator);
-  }
+        _exhaustivenessDataForTesting = exhaustivenessDataForTesting {}
 
   /// Whether to preserve constant [Field]s. All use-sites will be rewritten.
   bool get keepFields => backend.keepFields;
@@ -452,6 +450,9 @@ class ConstantsTransformer extends RemovingTransformer {
     _staticTypeContext =
         new StaticTypeContext.forAnnotations(library, typeEnvironment);
 
+    _exhaustivenessCache =
+        new CfeExhaustivenessCache(constantEvaluator, library);
+
     transformAnnotations(library.annotations, library);
 
     transformLibraryDependencyList(library.dependencies, library);
@@ -471,6 +472,7 @@ class ConstantsTransformer extends RemovingTransformer {
       });
     }
     _staticTypeContext = null;
+    _exhaustivenessCache = null;
   }
 
   @override
@@ -1537,22 +1539,22 @@ class ConstantsTransformer extends RemovingTransformer {
       required bool hasDefault,
       required bool mustBeExhaustive,
       required bool isSwitchExpression}) {
-    StaticType type = exhaustivenessCache.getStaticType(
+    StaticType type = _exhaustivenessCache!.getStaticType(
         // Treat invalid types as empty.
         expressionType is InvalidType
             ? const NeverType.nonNullable()
             : expressionType);
     List<Space> cases = [];
     PatternConverter patternConverter = new PatternConverter(
-        exhaustivenessCache, staticTypeContext,
+        _exhaustivenessCache!, staticTypeContext,
         hasPrimitiveEquality: (Constant constant) => constantEvaluator
             .hasPrimitiveEqual(constant, staticTypeContext: staticTypeContext));
     for (PatternGuard patternGuard in patternGuards) {
       cases.add(patternConverter.createRootSpace(type, patternGuard.pattern,
           hasGuard: patternGuard.guard != null));
     }
     List<ExhaustivenessError> errors =
-        reportErrors(exhaustivenessCache, type, cases);
+        reportErrors(_exhaustivenessCache!, type, cases);
     List<ExhaustivenessError>? reportedErrors;
     if (_exhaustivenessDataForTesting != null) {
       reportedErrors = [];
@@ -1592,7 +1594,7 @@ class ConstantsTransformer extends RemovingTransformer {
       }
     }
     if (_exhaustivenessDataForTesting != null) {
-      _exhaustivenessDataForTesting!.objectFieldLookup ??= exhaustivenessCache;
+      _exhaustivenessDataForTesting!.objectFieldLookup ??= _exhaustivenessCache;
       _exhaustivenessDataForTesting!.switchResults[replacement] =
           new ExhaustivenessResult(type, cases,
               patternGuards.map((c) => c.fileOffset).toList(), reportedErrors!);

pkg/front_end/lib/src/fasta/kernel/exhaustiveness.dart

@@ -46,8 +46,9 @@ class ExhaustivenessResult {
 
 class CfeTypeOperations implements TypeOperations<DartType> {
   final TypeEnvironment _typeEnvironment;
+  final Library _enclosingLibrary;
 
-  CfeTypeOperations(this._typeEnvironment);
+  CfeTypeOperations(this._typeEnvironment, this._enclosingLibrary);
 
   ClassHierarchy get _classHierarchy => _typeEnvironment.hierarchy;
 
@@ -122,7 +123,7 @@ class CfeTypeOperations implements TypeOperations<DartType> {
       Map<Class, Substitution> substitutions = {};
       for (Member member
           in _classHierarchy.getInterfaceMembers(type.classNode)) {
-        if (member.name.isPrivate) {
+        if (member.name.isPrivate && member.name.library != _enclosingLibrary) {
           continue;
         }
         DartType? fieldType;
@@ -396,10 +397,12 @@ class CfeExhaustivenessCache
     extends ExhaustivenessCache<DartType, Class, Class, Field, Constant> {
   final TypeEnvironment typeEnvironment;
 
-  CfeExhaustivenessCache(ConstantEvaluator constantEvaluator)
+  CfeExhaustivenessCache(
+      ConstantEvaluator constantEvaluator, Library enclosingLibrary)
       : typeEnvironment = constantEvaluator.typeEnvironment,
         super(
-            new CfeTypeOperations(constantEvaluator.typeEnvironment),
+            new CfeTypeOperations(
+                constantEvaluator.typeEnvironment, enclosingLibrary),
             new CfeEnumOperations(constantEvaluator),
             new CfeSealedClassOperations(constantEvaluator.typeEnvironment));
 }

pkg/front_end/testcases/patterns/exhaustiveness/issue52041.dart

@@ -0,0 +1,22 @@
+// Copyright (c) 2023, 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.
+
+sealed class B {}
+
+class C extends B {
+  final int _i;
+
+  C(this._i);
+}
+
+f(B b) {
+  switch (b) {
+    case C(:var _i):
+      print('C($_i)');
+  }
+}
+
+main() {
+  f(C(0));
+}

pkg/front_end/testcases/patterns/exhaustiveness/issue52041.dart.strong.expect

@@ -0,0 +1,32 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+
+abstract sealed class B extends core::Object {
+  synthetic constructor •() → self::B
+    : super core::Object::•()
+    ;
+}
+class C extends self::B {
+  final field core::int _i;
+  constructor •(core::int _i) → self::C
+    : self::C::_i = _i, super self::B::•()
+    ;
+}
+static method f(self::B b) → dynamic {
+  #L1:
+  {
+    final synthesized self::B #0#0 = b;
+    {
+      hoisted core::int _i;
+      if(#0#0 is{ForNonNullableByDefault} self::C && (let final dynamic #t1 = _i = #0#0{self::C}.{self::C::_i}{core::int} in true)) {
+        {
+          core::print("C(${_i})");
+        }
+      }
+    }
+  }
+}
+static method main() → dynamic {
+  self::f(new self::C::•(0));
+}

pkg/front_end/testcases/patterns/exhaustiveness/issue52041.dart.strong.transformed.expect

@@ -0,0 +1,32 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+
+abstract sealed class B extends core::Object {
+  synthetic constructor •() → self::B
+    : super core::Object::•()
+    ;
+}
+class C extends self::B {
+  final field core::int _i;
+  constructor •(core::int _i) → self::C
+    : self::C::_i = _i, super self::B::•()
+    ;
+}
+static method f(self::B b) → dynamic {
+  #L1:
+  {
+    final synthesized self::B #0#0 = b;
+    {
+      hoisted core::int _i;
+      if(#0#0 is{ForNonNullableByDefault} self::C && (let final core::int #t1 = _i = #0#0{self::C}.{self::C::_i}{core::int} in true)) {
+        {
+          core::print("C(${_i})");
+        }
+      }
+    }
+  }
+}
+static method main() → dynamic {
+  self::f(new self::C::•(0));
+}

pkg/front_end/testcases/patterns/exhaustiveness/issue52041.dart.textual_outline.expect

@@ -0,0 +1,9 @@
+sealed class B {}
+
+class C extends B {
+  final int _i;
+  C(this._i);
+}
+
+f(B b) {}
+main() {}

pkg/front_end/testcases/patterns/exhaustiveness/issue52041.dart.textual_outline_modelled.expect

@@ -0,0 +1,9 @@
+class C extends B {
+  C(this._i);
+  final int _i;
+}
+
+f(B b) {}
+main() {}
+
+sealed class B {}

pkg/front_end/testcases/patterns/exhaustiveness/issue52041.dart.weak.expect

@@ -0,0 +1,35 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+import "dart:_internal" as _in;
+
+abstract sealed class B extends core::Object {
+  synthetic constructor •() → self::B
+    : super core::Object::•()
+    ;
+}
+class C extends self::B {
+  final field core::int _i;
+  constructor •(core::int _i) → self::C
+    : self::C::_i = _i, super self::B::•()
+    ;
+}
+static method f(self::B b) → dynamic {
+  #L1:
+  {
+    final synthesized self::B #0#0 = b;
+    {
+      hoisted core::int _i;
+      if(#0#0 is{ForNonNullableByDefault} self::C && (let final dynamic #t1 = _i = #0#0{self::C}.{self::C::_i}{core::int} in true)) {
+        {
+          core::print("C(${_i})");
+        }
+      }
+      break #L1;
+    }
+    throw new _in::ReachabilityError::•("`null` encountered as case in a switch statement with a non-nullable type.");
+  }
+}
+static method main() → dynamic {
+  self::f(new self::C::•(0));
+}