Recover from default values in function types

Fixes https://github.com/dart-lang/sdk/issues/35035

Change-Id: I29fe0d792998c43f49877d97b61b3afc16c43cef
Reviewed-on: https://dart-review.googlesource.com/c/82984
Commit-Queue: Aske Simon Christensen <askesc@google.com>
Reviewed-by: Aske Simon Christensen <askesc@google.com>
Auto-Submit: Peter von der Ahé <ahe@google.com>

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

@@ -2686,8 +2686,12 @@ abstract class BodyBuilder extends ScopeListener<JumpTarget>
   void handleValuedFormalParameter(Token equals, Token token) {
     debugEvent("ValuedFormalParameter");
     Expression initializer = popForValue();
-    Identifier name = pop();
-    push(new InitializedIdentifier(name, initializer));
+    Object name = pop();
+    if (name is ParserRecovery) {
+      push(name);
+    } else {
+      push(new InitializedIdentifier(name, initializer));
+    }
   }
 
   @override

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

@@ -494,5 +494,5 @@ class ParserRecovery {
   final int charOffset;
   ParserRecovery(this.charOffset);
 
-  String toString() => "ParserRecovery(charOffset)";
+  String toString() => "ParserRecovery(@$charOffset)";
 }

pkg/front_end/testcases/function_type_default_value.dart

@@ -0,0 +1,7 @@
+// Copyright (c) 2018, 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.
+
+void Function({obj: Object}) x;
+
+main() {}

pkg/front_end/testcases/function_type_default_value.dart.direct.expect

@@ -0,0 +1,29 @@
+// Formatted problems:
+//
+// pkg/front_end/testcases/function_type_default_value.dart:5:19: Error: Expected an identifier, but got ':'.
+// void Function({obj: Object}) x;
+//                   ^
+//
+// pkg/front_end/testcases/function_type_default_value.dart:5:19: Error: Can't have a default value in a function type.
+// void Function({obj: Object}) x;
+//                   ^
+//
+// pkg/front_end/testcases/function_type_default_value.dart:5:16: Warning: 'obj' isn't a type.
+// void Function({obj: Object}) x;
+//                ^^^
+
+// Unhandled errors:
+//
+// pkg/front_end/testcases/function_type_default_value.dart:5:19: Error: Expected an identifier, but got ':'.
+// void Function({obj: Object}) x;
+//                   ^
+//
+// pkg/front_end/testcases/function_type_default_value.dart:5:19: Error: Can't have a default value in a function type.
+// void Function({obj: Object}) x;
+//                   ^
+
+library;
+import self as self;
+
+static field () → void x;
+static method main() → dynamic {}

pkg/front_end/testcases/function_type_default_value.dart.direct.transformed.expect

@@ -0,0 +1,15 @@
+// Unhandled errors:
+//
+// pkg/front_end/testcases/function_type_default_value.dart:5:19: Error: Expected an identifier, but got ':'.
+// void Function({obj: Object}) x;
+//                   ^
+//
+// pkg/front_end/testcases/function_type_default_value.dart:5:19: Error: Can't have a default value in a function type.
+// void Function({obj: Object}) x;
+//                   ^
+
+library;
+import self as self;
+
+static field () → void x;
+static method main() → dynamic {}

pkg/front_end/testcases/function_type_default_value.dart.outline.expect

@@ -0,0 +1,16 @@
+// Formatted problems:
+//
+// pkg/front_end/testcases/function_type_default_value.dart:5:19: Error: Expected an identifier, but got ':'.
+// void Function({obj: Object}) x;
+//                   ^
+//
+// pkg/front_end/testcases/function_type_default_value.dart:5:19: Error: Can't have a default value in a function type.
+// void Function({obj: Object}) x;
+//                   ^
+
+library;
+import self as self;
+
+static field () → void x;
+static method main() → dynamic
+  ;

pkg/front_end/testcases/function_type_default_value.dart.strong.expect

@@ -0,0 +1,33 @@
+// Formatted problems:
+//
+// pkg/front_end/testcases/function_type_default_value.dart:5:19: Error: Expected an identifier, but got ':'.
+// void Function({obj: Object}) x;
+//                   ^
+//
+// pkg/front_end/testcases/function_type_default_value.dart:5:19: Error: Can't have a default value in a function type.
+// void Function({obj: Object}) x;
+//                   ^
+//
+// pkg/front_end/testcases/function_type_default_value.dart:5:16: Error: 'obj' isn't a type.
+// void Function({obj: Object}) x;
+//                ^^^
+
+// Unhandled errors:
+//
+// pkg/front_end/testcases/function_type_default_value.dart:5:19: Error: Expected an identifier, but got ':'.
+// void Function({obj: Object}) x;
+//                   ^
+//
+// pkg/front_end/testcases/function_type_default_value.dart:5:19: Error: Can't have a default value in a function type.
+// void Function({obj: Object}) x;
+//                   ^
+//
+// pkg/front_end/testcases/function_type_default_value.dart:5:16: Error: 'obj' isn't a type.
+// void Function({obj: Object}) x;
+//                ^^^
+
+library;
+import self as self;
+
+static field () → void x;
+static method main() → dynamic {}

pkg/front_end/testcases/function_type_default_value.dart.strong.transformed.expect

@@ -0,0 +1,19 @@
+// Unhandled errors:
+//
+// pkg/front_end/testcases/function_type_default_value.dart:5:19: Error: Expected an identifier, but got ':'.
+// void Function({obj: Object}) x;
+//                   ^
+//
+// pkg/front_end/testcases/function_type_default_value.dart:5:19: Error: Can't have a default value in a function type.
+// void Function({obj: Object}) x;
+//                   ^
+//
+// pkg/front_end/testcases/function_type_default_value.dart:5:16: Error: 'obj' isn't a type.
+// void Function({obj: Object}) x;
+//                ^^^
+
+library;
+import self as self;
+
+static field () → void x;
+static method main() → dynamic {}