Add cycle detection test cases for nonfunction type aliases.

Change-Id: I4375c3374ba5d51b4431dbe22a0e8c867a4eb03d
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/167720
Reviewed-by: Erik Ernst <eernst@google.com>
Commit-Queue: Paul Berry <paulberry@google.com>

tests/language/nonfunction_type_aliases/cyclic_bound_error_test.dart

@@ -0,0 +1,65 @@
+// Copyright (c) 2020, 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.
+
+// SharedOptions=--enable-experiment=nonfunction-type-aliases
+
+// This test verifies that cyclic type alias definitions cause a compile-time
+// error, when the cycle occurs via the bound.
+
+typedef T1<X extends T1<Never>> = List<X>;
+//      ^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+// Note: when the cycle involves two typedefs, the CFE only reports an error for
+// one of them; that's ok.
+typedef T2<X extends T3> = List<X>;
+//      ^
+// [analyzer] unspecified
+
+typedef T3 = T2<Never>;
+//      ^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+typedef T4<X extends List<T4<Never>>> = List<X>;
+//      ^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+typedef T5<X extends T5<Never> Function()> = List<X>;
+//      ^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+typedef T6<X extends void Function(T6<Never>)> = List<X>;
+//      ^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+// Note: not an error because T7 is the name of the parameter.
+typedef T7<X extends void Function(int T7)> = List<X>;
+
+typedef T8<X extends void Function([T8<Never>])> = List<X>;
+//      ^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+// Note: not an error because T9 is the name of the parameter.
+typedef T9<X extends void Function([int T9])> = List<X>;
+
+typedef T10<X extends void Function({T10<Never> x})> = List<X>;
+//      ^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+// Note: not an error because T11 is the name of the parameter.
+typedef T11<X extends void Function({int T11})> = List<X>;
+
+// Note: we have to use `void Function<...>() Function()` because a generic
+// function can't directly be used as a bound.
+typedef T12<X extends void Function<Y extends T12<Never>>() Function()> = List<X>;
+//      ^
+// [analyzer] unspecified
+// [cfe] unspecified

tests/language/nonfunction_type_aliases/cyclic_bound_unused_error_test.dart

@@ -0,0 +1,66 @@
+// Copyright (c) 2020, 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.
+
+// SharedOptions=--enable-experiment=nonfunction-type-aliases
+
+// This test verifies that cyclic type alias definitions cause a compile-time
+// error, when the cycle occurs via the bound, even if the bound variable is not
+// used in the expansion.
+
+typedef T1<X extends T1<Never>> = int;
+//      ^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+// Note: when the cycle involves two typedefs, the CFE only reports an error for
+// one of them; that's ok.
+typedef T2<X extends T3> = int;
+//      ^
+// [analyzer] unspecified
+
+typedef T3 = T2<Never>;
+//      ^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+typedef T4<X extends List<T4<Never>>> = int;
+//      ^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+typedef T5<X extends T5<Never> Function()> = int;
+//      ^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+typedef T6<X extends void Function(T6<Never>)> = int;
+//      ^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+// Note: not an error because T7 is the name of the parameter.
+typedef T7<X extends void Function(int T7)> = int;
+
+typedef T8<X extends void Function([T8<Never>])> = int;
+//      ^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+// Note: not an error because T9 is the name of the parameter.
+typedef T9<X extends void Function([int T9])> = int;
+
+typedef T10<X extends void Function({T10<Never> x})> = int;
+//      ^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+// Note: not an error because T11 is the name of the parameter.
+typedef T11<X extends void Function({int T11})> = int;
+
+// Note: we have to use `void Function<...>() Function()` because a generic
+// function can't directly be used as a bound.
+typedef T12<X extends void Function<Y extends T12<Never>>() Function()> = int;
+//      ^
+// [analyzer] unspecified
+// [cfe] unspecified

tests/language/nonfunction_type_aliases/cyclic_expansion_error_test.dart

@@ -0,0 +1,70 @@
+// Copyright (c) 2020, 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.
+
+// SharedOptions=--enable-experiment=nonfunction-type-aliases
+
+// This test verifies that cyclic type alias definitions cause a compile-time
+// error, when the cycle occurs via the expansion of the type.
+
+typedef T1 = List<T1>;
+//      ^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+typedef T2 = List<T3>;
+//      ^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+// Note: when the cycle involves two typedefs, the CFE only reports an error for
+// one of them; that's ok.
+typedef T3 = List<T2>;
+//      ^
+// [analyzer] unspecified
+
+typedef T4 = T4;
+//      ^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+typedef T5 = T5?;
+//      ^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+typedef T6 = List<T6 Function()>;
+//      ^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+typedef T7 = List<void Function(T7)>;
+//      ^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+// Note: not an error because T8 is the name of the parameter.
+typedef T8 = List<void Function(int T8)>;
+
+typedef T9 = List<void Function([T9])>;
+//      ^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+// Note: not an error because T10 is the name of the parameter.
+typedef T10 = List<void Function([int T10])>;
+
+typedef T11 = List<void Function({T11 x})>;
+//      ^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+// Note: not an error because T12 is the name of the parameter.
+typedef T12 = List<void Function({int T12})>;
+
+// Note: we have to use `void Function<...>() Function()` because a generic
+// function can't directly be used as a type argument.
+typedef T13 = List<void Function<X extends T13>() Function()>;
+//      ^
+// [analyzer] unspecified
+// [cfe] unspecified