[cfe] Don't crash on constructors in extensions

Change-Id: I11cdb9699101f384c2734c3551b4eefdfda6eccb
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/118980
Commit-Queue: Johnni Winther <johnniwinther@google.com>
Reviewed-by: Jens Johansen <jensj@google.com>

pkg/front_end/lib/src/fasta/source/diet_listener.dart

@@ -585,6 +585,28 @@ class DietListener extends StackListener {
     }
   }
 
+  @override
+  void endExtensionFactoryMethod(
+      Token beginToken, Token factoryKeyword, Token endToken) {
+    debugEvent("ExtensionFactoryMethod");
+    pop(); // bodyToken
+    pop(); // name
+    pop(); // metadata
+    checkEmpty(beginToken.charOffset);
+    // Skip the declaration. An error as already been produced by the parser.
+  }
+
+  @override
+  void endExtensionConstructor(Token getOrSet, Token beginToken,
+      Token beginParam, Token beginInitializers, Token endToken) {
+    debugEvent("ExtensionConstructor");
+    pop(); // bodyToken
+    pop(); // name
+    pop(); // metadata
+    checkEmpty(beginToken.charOffset);
+    // Skip the declaration. An error as already been produced by the parser.
+  }
+
   @override
   void endRedirectingFactoryBody(Token beginToken, Token endToken) {
     debugEvent("RedirectingFactoryBody");

pkg/front_end/testcases/extensions/extension_constructor.dart

@@ -0,0 +1,16 @@
+// Copyright (c) 2019, 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.
+
+class Class {}
+
+extension Extension on Class {
+  Extension() {}
+  Extension.named() {}
+  factory Extension.fact() => null;
+  factory Extension.redirect() = Extension;
+
+  method() {}
+}
+
+main() {}

pkg/front_end/testcases/extensions/extension_constructor.dart.outline.expect

@@ -0,0 +1,55 @@
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/extensions/extension_constructor.dart:8:3: Error: Extensions can't declare constructors.
+// Try removing the constructor declaration.
+//   Extension() {}
+//   ^^^^^^^^^
+//
+// pkg/front_end/testcases/extensions/extension_constructor.dart:9:3: Error: Extensions can't declare constructors.
+// Try removing the constructor declaration.
+//   Extension.named() {}
+//   ^^^^^^^^^
+//
+// pkg/front_end/testcases/extensions/extension_constructor.dart:10:3: Error: Extensions can't declare constructors.
+// Try removing the constructor declaration.
+//   factory Extension.fact() => null;
+//   ^^^^^^^
+//
+// pkg/front_end/testcases/extensions/extension_constructor.dart:11:3: Error: Extensions can't declare constructors.
+// Try removing the constructor declaration.
+//   factory Extension.redirect() = Extension;
+//   ^^^^^^^
+//
+// pkg/front_end/testcases/extensions/extension_constructor.dart:10:11: Error: 'Extension' isn't a type.
+//   factory Extension.fact() => null;
+//           ^^^^^^^^^
+// pkg/front_end/testcases/extensions/extension_constructor.dart:7:11: Context: This isn't a type.
+// extension Extension on Class {
+//           ^^^^^^^^^
+//
+// pkg/front_end/testcases/extensions/extension_constructor.dart:11:11: Error: 'Extension' isn't a type.
+//   factory Extension.redirect() = Extension;
+//           ^^^^^^^^^
+// pkg/front_end/testcases/extensions/extension_constructor.dart:7:11: Context: This isn't a type.
+// extension Extension on Class {
+//           ^^^^^^^^^
+//
+import self as self;
+import "dart:core" as core;
+
+class Class extends core::Object {
+  synthetic constructor •() → self::Class*
+    ;
+}
+extension Extension on self::Class* {
+  method method = self::Extension|method;
+  tearoff method = self::Extension|get#method;
+}
+static method Extension|method(final self::Class* #this) → dynamic
+  ;
+static method Extension|get#method(final self::Class* #this) → () →* dynamic
+  return () → dynamic => self::Extension|method(#this);
+static method main() → dynamic
+  ;

pkg/front_end/testcases/extensions/extension_constructor.dart.strong.expect

@@ -0,0 +1,54 @@
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/extensions/extension_constructor.dart:8:3: Error: Extensions can't declare constructors.
+// Try removing the constructor declaration.
+//   Extension() {}
+//   ^^^^^^^^^
+//
+// pkg/front_end/testcases/extensions/extension_constructor.dart:9:3: Error: Extensions can't declare constructors.
+// Try removing the constructor declaration.
+//   Extension.named() {}
+//   ^^^^^^^^^
+//
+// pkg/front_end/testcases/extensions/extension_constructor.dart:10:3: Error: Extensions can't declare constructors.
+// Try removing the constructor declaration.
+//   factory Extension.fact() => null;
+//   ^^^^^^^
+//
+// pkg/front_end/testcases/extensions/extension_constructor.dart:11:3: Error: Extensions can't declare constructors.
+// Try removing the constructor declaration.
+//   factory Extension.redirect() = Extension;
+//   ^^^^^^^
+//
+// pkg/front_end/testcases/extensions/extension_constructor.dart:10:11: Error: 'Extension' isn't a type.
+//   factory Extension.fact() => null;
+//           ^^^^^^^^^
+// pkg/front_end/testcases/extensions/extension_constructor.dart:7:11: Context: This isn't a type.
+// extension Extension on Class {
+//           ^^^^^^^^^
+//
+// pkg/front_end/testcases/extensions/extension_constructor.dart:11:11: Error: 'Extension' isn't a type.
+//   factory Extension.redirect() = Extension;
+//           ^^^^^^^^^
+// pkg/front_end/testcases/extensions/extension_constructor.dart:7:11: Context: This isn't a type.
+// extension Extension on Class {
+//           ^^^^^^^^^
+//
+import self as self;
+import "dart:core" as core;
+
+class Class extends core::Object {
+  synthetic constructor •() → self::Class*
+    : super core::Object::•()
+    ;
+}
+extension Extension on self::Class* {
+  method method = self::Extension|method;
+  tearoff method = self::Extension|get#method;
+}
+static method Extension|method(final self::Class* #this) → dynamic {}
+static method Extension|get#method(final self::Class* #this) → () →* dynamic
+  return () → dynamic => self::Extension|method(#this);
+static method main() → dynamic {}

pkg/front_end/testcases/extensions/extension_constructor.dart.strong.transformed.expect

@@ -0,0 +1,54 @@
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/extensions/extension_constructor.dart:8:3: Error: Extensions can't declare constructors.
+// Try removing the constructor declaration.
+//   Extension() {}
+//   ^^^^^^^^^
+//
+// pkg/front_end/testcases/extensions/extension_constructor.dart:9:3: Error: Extensions can't declare constructors.
+// Try removing the constructor declaration.
+//   Extension.named() {}
+//   ^^^^^^^^^
+//
+// pkg/front_end/testcases/extensions/extension_constructor.dart:10:3: Error: Extensions can't declare constructors.
+// Try removing the constructor declaration.
+//   factory Extension.fact() => null;
+//   ^^^^^^^
+//
+// pkg/front_end/testcases/extensions/extension_constructor.dart:11:3: Error: Extensions can't declare constructors.
+// Try removing the constructor declaration.
+//   factory Extension.redirect() = Extension;
+//   ^^^^^^^
+//
+// pkg/front_end/testcases/extensions/extension_constructor.dart:10:11: Error: 'Extension' isn't a type.
+//   factory Extension.fact() => null;
+//           ^^^^^^^^^
+// pkg/front_end/testcases/extensions/extension_constructor.dart:7:11: Context: This isn't a type.
+// extension Extension on Class {
+//           ^^^^^^^^^
+//
+// pkg/front_end/testcases/extensions/extension_constructor.dart:11:11: Error: 'Extension' isn't a type.
+//   factory Extension.redirect() = Extension;
+//           ^^^^^^^^^
+// pkg/front_end/testcases/extensions/extension_constructor.dart:7:11: Context: This isn't a type.
+// extension Extension on Class {
+//           ^^^^^^^^^
+//
+import self as self;
+import "dart:core" as core;
+
+class Class extends core::Object {
+  synthetic constructor •() → self::Class*
+    : super core::Object::•()
+    ;
+}
+extension Extension on self::Class* {
+  method method = self::Extension|method;
+  tearoff method = self::Extension|get#method;
+}
+static method Extension|method(final self::Class* #this) → dynamic {}
+static method Extension|get#method(final self::Class* #this) → () →* dynamic
+  return () → dynamic => self::Extension|method(#this);
+static method main() → dynamic {}

pkg/front_end/testcases/text_serialization.status

@@ -23,6 +23,7 @@ extensions/explicit_generic_extension_access: TextSerializationFailure
 extensions/explicit_invalid_access: TextSerializationFailure
 extensions/explicit_this: TextSerializationFailure
 extensions/extension_call: TextSerializationFailure
+extensions/extension_constructor: TextSerializationFailure
 extensions/extension_methods: TextSerializationFailure
 extensions/extension_setter: TextSerializationFailure
 extensions/extension_setter_error: TypeCheckError