[CFE] Fix even more crashes on invalid this references

Change-Id: Id7d594f52b0344dd5d3e41e683594cbd213e96b9
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/396001
Reviewed-by: Johnni Winther <[email protected]>
Commit-Queue: Jens Johansen <[email protected]>

Author: jensjoha

pkg/front_end/lib/src/kernel/body_builder.dart

@@ -3198,7 +3198,10 @@ class BodyBuilder extends StackListenerImpl
     }
     if (declaration != null &&
         declaration.isDeclarationInstanceMember &&
-        (inFieldInitializer && !inLateFieldInitializer) &&
+        (inFieldInitializer &&
+            (!inLateFieldInitializer ||
+                _context.isExtensionDeclaration ||
+                _context.isExtensionTypeDeclaration)) &&
         !inInitializerLeftHandSide) {
       // We cannot access a class instance member in an initializer of a
       // field.
@@ -3210,6 +3213,8 @@ class BodyBuilder extends StackListenerImpl
       //       int bar;
       //     }
       //
+      // We can if it's late, but not if we're in an extension (type), even if
+      // it's late.
       return new IncompleteErrorGenerator(this, nameToken,
           cfe.templateThisAccessInFieldInitializer.withArguments(name));
     }
@@ -3232,6 +3237,11 @@ class BodyBuilder extends StackListenerImpl
           // implicit access on the 'this' parameter.
           return PropertyAccessGenerator.make(this, nameToken,
               createVariableGet(thisVariable!, nameOffset), n, false);
+        } else if (_context.isExtensionDeclaration ||
+            _context.isExtensionTypeDeclaration) {
+          // In an extension (type) without a this variable.
+          return new UnresolvedNameGenerator(this, nameToken, n,
+              unresolvedReadKind: UnresolvedKind.Unknown);
         } else {
           // This is an implicit access on 'this'.
           return new ThisPropertyAccessGenerator(this, nameToken, n,
@@ -3305,9 +3315,16 @@ class BodyBuilder extends StackListenerImpl
           thisVariable: inConstructorInitializer ? null : thisVariable);
     } else if (declaration.isExtensionInstanceMember) {
       // TODO(johnniwinther): Better check for constantContext like below/above?
+      // Possibly if the is a non-none constant context it's just a no without
+      // additional checks?
       if (constantContext != ConstantContext.none && thisVariable == null) {
         return new IncompleteErrorGenerator(
             this, nameToken, cfe.messageNotAConstantExpression);
+      } else if (constantContext != ConstantContext.none &&
+          !inInitializerLeftHandSide &&
+          !_context.isConstructor) {
+        return new IncompleteErrorGenerator(
+            this, nameToken, cfe.messageNotAConstantExpression);
       }
       ExtensionBuilder extensionBuilder =
           declaration.parent as ExtensionBuilder;
@@ -7190,6 +7207,12 @@ class BodyBuilder extends StackListenerImpl
           push(_createReadOnlyVariableAccess(thisVariable!, token,
               offsetForToken(token), 'this', ReadOnlyAccessKind.ExtensionThis));
         }
+      } else if ((!inConstructorInitializer || !inInitializerLeftHandSide) &&
+          (_context.isExtensionDeclaration ||
+              _context.isExtensionTypeDeclaration)) {
+        // In an extension (type) where we don't (here) have a "this" variable.
+        push(new IncompleteErrorGenerator(
+            this, token, cfe.messageThisAsIdentifier));
       } else {
         push(new ThisAccessGenerator(this, token, inInitializerLeftHandSide,
             inFieldInitializer, inLateFieldInitializer));

pkg/front_end/lib/src/kernel/body_builder_context.dart

@@ -115,6 +115,13 @@ abstract class BodyBuilderContext {
   /// Returns `true` if the enclosing class in an augmenting class.
   bool get isAugmentationClass => _declarationContext.isAugmentationClass;
 
+  /// Returns `true` if the enclosing entity is an extension type.
+  bool get isExtensionTypeDeclaration =>
+      _declarationContext.isExtensionTypeDeclaration;
+
+  /// Returns `true` if the enclosing entity is an extension.
+  bool get isExtensionDeclaration => _declarationContext.isExtensionDeclaration;
+
   /// Looks up the static member by the given [name] in the origin of the
   /// enclosing declaration.
   Builder? lookupStaticOriginMember(String name, int fileOffset, Uri fileUri) {
@@ -409,6 +416,11 @@ abstract class BodyBuilderDeclarationContext {
 
   bool get isAugmentationClass => false;
 
+  bool get isExtensionTypeDeclaration => false;
+
+  // Coverage-ignore(suite): Not run.
+  bool get isExtensionDeclaration => false;
+
   Builder? lookupStaticOriginMember(String name, int fileOffset, Uri fileUri) {
     throw new UnsupportedError('${runtimeType}.lookupStaticOriginMember');
   }
@@ -449,6 +461,9 @@ mixin _DeclarationBodyBuilderDeclarationContextMixin
 
   @override
   InterfaceType? get thisType => _declarationBuilder.thisType;
+
+  @override
+  bool get isExtensionDeclaration => _declarationBuilder.isExtension;
 }
 
 class _SourceClassBodyBuilderDeclarationContext
@@ -606,6 +621,9 @@ class _SourceExtensionTypeDeclarationBodyBuilderDeclarationContext
   String get className {
     return _sourceExtensionTypeDeclarationBuilder.fullNameForErrors;
   }
+
+  @override
+  bool get isExtensionTypeDeclaration => true;
 }
 
 class _DeclarationBodyBuilderDeclarationContext

pkg/front_end/lib/src/source/outline_builder.dart

@@ -3479,7 +3479,6 @@ class OutlineBuilder extends StackListenerImpl {
     }
 
     if (inConstructorName) {
-      // Coverage-ignore-block(suite): Not run.
       addProblem(messageConstructorWithTypeParameters,
           offsetForToken(beginToken), lengthOfSpan(beginToken, endToken));
       inConstructorName = false;

pkg/front_end/lib/src/source/source_field_builder.dart

@@ -2138,7 +2138,6 @@ class RepresentationFieldEncoding implements FieldEncoding {
       const <ClassMember>[];
 
   @override
-  // Coverage-ignore(suite): Not run.
   void buildImplicitDefaultValue() {
     // Not needed.
   }

pkg/front_end/test/coverage_suite_expected.dart

@@ -205,7 +205,7 @@ const Map<String, ({int hitCount, int missCount})> _expect = {
   ),
   // 100.0%.
   "package:front_end/src/base/processed_options.dart": (
-    hitCount: 261,
+    hitCount: 260,
     missCount: 0,
   ),
   // 100.0%.
@@ -290,7 +290,7 @@ const Map<String, ({int hitCount, int missCount})> _expect = {
   ),
   // 100.0%.
   "package:front_end/src/builder/formal_parameter_builder.dart": (
-    hitCount: 186,
+    hitCount: 188,
     missCount: 0,
   ),
   // 100.0%.
@@ -560,12 +560,12 @@ const Map<String, ({int hitCount, int missCount})> _expect = {
   ),
   // 100.0%.
   "package:front_end/src/kernel/body_builder.dart": (
-    hitCount: 7147,
+    hitCount: 7173,
     missCount: 0,
   ),
   // 100.0%.
   "package:front_end/src/kernel/body_builder_context.dart": (
-    hitCount: 346,
+    hitCount: 357,
     missCount: 0,
   ),
   // 100.0%.
@@ -870,7 +870,7 @@ const Map<String, ({int hitCount, int missCount})> _expect = {
   ),
   // 100.0%.
   "package:front_end/src/source/outline_builder.dart": (
-    hitCount: 2122,
+    hitCount: 2126,
     missCount: 0,
   ),
   // 100.0%.
@@ -900,7 +900,7 @@ const Map<String, ({int hitCount, int missCount})> _expect = {
   ),
   // 100.0%.
   "package:front_end/src/source/source_constructor_builder.dart": (
-    hitCount: 894,
+    hitCount: 895,
     missCount: 0,
   ),
   // 100.0%.
@@ -926,12 +926,12 @@ const Map<String, ({int hitCount, int missCount})> _expect = {
   ),
   // 100.0%.
   "package:front_end/src/source/source_field_builder.dart": (
-    hitCount: 1245,
+    hitCount: 1246,
     missCount: 0,
   ),
   // 100.0%.
   "package:front_end/src/source/source_function_builder.dart": (
-    hitCount: 314,
+    hitCount: 316,
     missCount: 0,
   ),
   // 100.0%.
@@ -941,7 +941,7 @@ const Map<String, ({int hitCount, int missCount})> _expect = {
   ),
   // 100.0%.
   "package:front_end/src/source/source_loader.dart": (
-    hitCount: 1855,
+    hitCount: 1857,
     missCount: 0,
   ),
   // 100.0%.

pkg/front_end/testcases/regress/invalid_this_reference_07.dart

@@ -0,0 +1,23 @@
+// Copyright (c) 2024, 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.
+
+extension type Foo(dynamic d) {
+  // Bad
+  var foo = this();
+
+  bar() {
+    // OK
+    return this;
+  }
+}
+
+class FooClass {
+  // Bad
+  var foo = this();
+
+  bar() {
+    // OK
+    return this;
+  }
+}

pkg/front_end/testcases/regress/invalid_this_reference_07.dart.strong.expect

@@ -0,0 +1,54 @@
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/regress/invalid_this_reference_07.dart:7:7: Error: Extension types can't declare instance fields
+// Try removing the field declaration or making it a static field
+//   var foo = this();
+//       ^^^
+//
+// pkg/front_end/testcases/regress/invalid_this_reference_07.dart:7:13: Error: Expected identifier, but got 'this'.
+//   var foo = this();
+//             ^^^^
+//
+// pkg/front_end/testcases/regress/invalid_this_reference_07.dart:17:13: Error: The method 'call' isn't defined for the class 'FooClass'.
+//  - 'FooClass' is from 'pkg/front_end/testcases/regress/invalid_this_reference_07.dart'.
+// Try correcting the name to the name of an existing method, or defining a method named 'call'.
+//   var foo = this();
+//             ^
+//
+import self as self;
+import "dart:core" as core;
+
+class FooClass extends core::Object {
+  field dynamic foo = invalid-expression "pkg/front_end/testcases/regress/invalid_this_reference_07.dart:17:13: Error: The method 'call' isn't defined for the class 'FooClass'.
+ - 'FooClass' is from 'pkg/front_end/testcases/regress/invalid_this_reference_07.dart'.
+Try correcting the name to the name of an existing method, or defining a method named 'call'.
+  var foo = this();
+            ^" in this{<unresolved>}.call();
+  synthetic constructor •() → self::FooClass
+    : super core::Object::•()
+    ;
+  method bar() → dynamic {
+    return this;
+  }
+}
+extension type Foo(dynamic d) {
+  abstract extension-type-member representation-field get d() → dynamic;
+  abstract extension-type-member representation-field get foo() → invalid-type;
+  method bar = self::Foo|bar;
+  method tearoff bar = self::Foo|get#bar;
+  constructor • = self::Foo|constructor#;
+  constructor tearoff • = self::Foo|constructor#_#new#tearOff;
+}
+static extension-type-member method Foo|constructor#(dynamic d) → self::Foo% /* erasure=dynamic, declared=! */ {
+  lowered final self::Foo% /* erasure=dynamic, declared=! */ #this = d;
+  return #this;
+}
+static extension-type-member method Foo|constructor#_#new#tearOff(dynamic d) → self::Foo% /* erasure=dynamic, declared=! */
+  return self::Foo|constructor#(d);
+static extension-type-member method Foo|bar(lowered final self::Foo% /* erasure=dynamic, declared=! */ #this) → dynamic {
+  return #this;
+}
+static extension-type-member method Foo|get#bar(lowered final self::Foo% /* erasure=dynamic, declared=! */ #this) → () → dynamic
+  return () → dynamic => self::Foo|bar(#this);

pkg/front_end/testcases/regress/invalid_this_reference_07.dart.strong.modular.expect

@@ -0,0 +1,54 @@
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/regress/invalid_this_reference_07.dart:7:7: Error: Extension types can't declare instance fields
+// Try removing the field declaration or making it a static field
+//   var foo = this();
+//       ^^^
+//
+// pkg/front_end/testcases/regress/invalid_this_reference_07.dart:7:13: Error: Expected identifier, but got 'this'.
+//   var foo = this();
+//             ^^^^
+//
+// pkg/front_end/testcases/regress/invalid_this_reference_07.dart:17:13: Error: The method 'call' isn't defined for the class 'FooClass'.
+//  - 'FooClass' is from 'pkg/front_end/testcases/regress/invalid_this_reference_07.dart'.
+// Try correcting the name to the name of an existing method, or defining a method named 'call'.
+//   var foo = this();
+//             ^
+//
+import self as self;
+import "dart:core" as core;
+
+class FooClass extends core::Object {
+  field dynamic foo = invalid-expression "pkg/front_end/testcases/regress/invalid_this_reference_07.dart:17:13: Error: The method 'call' isn't defined for the class 'FooClass'.
+ - 'FooClass' is from 'pkg/front_end/testcases/regress/invalid_this_reference_07.dart'.
+Try correcting the name to the name of an existing method, or defining a method named 'call'.
+  var foo = this();
+            ^" in this{<unresolved>}.call();
+  synthetic constructor •() → self::FooClass
+    : super core::Object::•()
+    ;
+  method bar() → dynamic {
+    return this;
+  }
+}
+extension type Foo(dynamic d) {
+  abstract extension-type-member representation-field get d() → dynamic;
+  abstract extension-type-member representation-field get foo() → invalid-type;
+  method bar = self::Foo|bar;
+  method tearoff bar = self::Foo|get#bar;
+  constructor • = self::Foo|constructor#;
+  constructor tearoff • = self::Foo|constructor#_#new#tearOff;
+}
+static extension-type-member method Foo|constructor#(dynamic d) → self::Foo% /* erasure=dynamic, declared=! */ {
+  lowered final self::Foo% /* erasure=dynamic, declared=! */ #this = d;
+  return #this;
+}
+static extension-type-member method Foo|constructor#_#new#tearOff(dynamic d) → self::Foo% /* erasure=dynamic, declared=! */
+  return self::Foo|constructor#(d);
+static extension-type-member method Foo|bar(lowered final self::Foo% /* erasure=dynamic, declared=! */ #this) → dynamic {
+  return #this;
+}
+static extension-type-member method Foo|get#bar(lowered final self::Foo% /* erasure=dynamic, declared=! */ #this) → () → dynamic
+  return () → dynamic => self::Foo|bar(#this);

pkg/front_end/testcases/regress/invalid_this_reference_07.dart.strong.outline.expect

@@ -0,0 +1,45 @@
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/regress/invalid_this_reference_07.dart:7:7: Error: Extension types can't declare instance fields
+// Try removing the field declaration or making it a static field
+//   var foo = this();
+//       ^^^
+//
+// pkg/front_end/testcases/regress/invalid_this_reference_07.dart:7:13: Error: Expected identifier, but got 'this'.
+//   var foo = this();
+//             ^^^^
+//
+// pkg/front_end/testcases/regress/invalid_this_reference_07.dart:17:13: Error: The method 'call' isn't defined for the class 'FooClass'.
+//  - 'FooClass' is from 'pkg/front_end/testcases/regress/invalid_this_reference_07.dart'.
+// Try correcting the name to the name of an existing method, or defining a method named 'call'.
+//   var foo = this();
+//             ^
+//
+import self as self;
+import "dart:core" as core;
+
+class FooClass extends core::Object {
+  field dynamic foo;
+  synthetic constructor •() → self::FooClass
+    ;
+  method bar() → dynamic
+    ;
+}
+extension type Foo(dynamic d) {
+  abstract extension-type-member representation-field get d() → dynamic;
+  abstract extension-type-member representation-field get foo() → invalid-type;
+  method bar = self::Foo|bar;
+  method tearoff bar = self::Foo|get#bar;
+  constructor • = self::Foo|constructor#;
+  constructor tearoff • = self::Foo|constructor#_#new#tearOff;
+}
+static extension-type-member method Foo|constructor#(dynamic d) → self::Foo% /* erasure=dynamic, declared=! */
+  ;
+static extension-type-member method Foo|constructor#_#new#tearOff(dynamic d) → self::Foo% /* erasure=dynamic, declared=! */
+  return self::Foo|constructor#(d);
+static extension-type-member method Foo|bar(lowered final self::Foo% /* erasure=dynamic, declared=! */ #this) → dynamic
+  ;
+static extension-type-member method Foo|get#bar(lowered final self::Foo% /* erasure=dynamic, declared=! */ #this) → () → dynamic
+  return () → dynamic => self::Foo|bar(#this);