Issue #996: more tests for Generic functions as type arguments and bo…

…unds added.

LanguageFeatures/Generic-functions-as-type-args/typedef1_A02_t01.dart

@@ -0,0 +1,61 @@
+/*
+ * Copyright (c) 2021, 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.
+ */
+/**
+ * @assertion Allow generic function types as type arguments and bounds
+ *
+ * The language disallows generic function types as type arguments and bounds.
+ *
+ *  late List<T Function<T>(T)> idFunctions; // INVALID.
+ *  var callback = [foo<T>(T value) => value]; // Inferred as above, then invalid.
+ *  late S Function<S extends T Function<T>(T)>(S) f; // INVALID.
+ *
+ * We remove that restriction, so a type argument and a bound can be a generic
+ * function type.
+ *
+ * This requires no new syntax, and in some cases only the removal of a single
+ * check. There might be some platforms where the implementation currently
+ * assumes that generic function types cannot occur as the value of type
+ * variables (an proof-of-concept attempt hit an assert in the VM). Such
+ * assumptions will need to be flushed out with tests and fixed.
+ *
+ * Because we already infer List<T Function<T>(T)> in the code above, this
+ * change will not affect type inference, it will just make the inferred type
+ * not be an error afterwards.
+ *
+ * We do not expect the removal of this restriction to affect the feasibility of
+ * type inference. After all, it's already possible to have a generic function
+ * type occurring covariantly in a type argument, like List<T Function<T>(T)
+ * Function()>.
+ * @description Checks that generic function can be a function type alias
+ * argument and bound.
+ * @author [email protected]
+ */
+//--enable-experiment=generic-metadata
+
+import "../../Utils/expect.dart";
+
+typedef T1<TT extends T Function<T>(T)> = TT Function();
+typedef T2<TT extends T Function<T>(T)> = void Function(TT);
+typedef T3<TT extends T Function<T>(T)> = TT Function(TT);
+typedef T4<TT extends T Function<T>(T)> = void Function<TTT extends TT>();
+typedef T5<TT extends T Function<T>(T)> = TTT Function<TTT extends TT>(TTT);
+typedef T6<TT extends T Function<T>(T)> = void Function();
+
+typedef exp1 = T Function<T>(T) Function();
+typedef exp2 = void Function(T Function<T>(T));
+typedef exp3 = T Function<T>(T) Function(T Function<T>(T));
+typedef exp4 = void Function<T extends T Function<T>(T)>();
+typedef exp5 = T Function<T extends T Function<T>(T)>(T);
+typedef exp6 = void Function();
+
+main() {
+  Expect.equals(exp1, T1);
+  Expect.equals(exp2, T2);
+  Expect.equals(exp3, T3);
+  Expect.equals(exp4, T4);
+  Expect.equals(exp5, T5);
+  Expect.equals(exp6, T6);
+}

LanguageFeatures/Generic-functions-as-type-args/typedef1_A02_t02.dart

@@ -0,0 +1,61 @@
+/*
+ * Copyright (c) 2021, 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.
+ */
+/**
+ * @assertion Allow generic function types as type arguments and bounds
+ *
+ * The language disallows generic function types as type arguments and bounds.
+ *
+ *  late List<T Function<T>(T)> idFunctions; // INVALID.
+ *  var callback = [foo<T>(T value) => value]; // Inferred as above, then invalid.
+ *  late S Function<S extends T Function<T>(T)>(S) f; // INVALID.
+ *
+ * We remove that restriction, so a type argument and a bound can be a generic
+ * function type.
+ *
+ * This requires no new syntax, and in some cases only the removal of a single
+ * check. There might be some platforms where the implementation currently
+ * assumes that generic function types cannot occur as the value of type
+ * variables (an proof-of-concept attempt hit an assert in the VM). Such
+ * assumptions will need to be flushed out with tests and fixed.
+ *
+ * Because we already infer List<T Function<T>(T)> in the code above, this
+ * change will not affect type inference, it will just make the inferred type
+ * not be an error afterwards.
+ *
+ * We do not expect the removal of this restriction to affect the feasibility of
+ * type inference. After all, it's already possible to have a generic function
+ * type occurring covariantly in a type argument, like List<T Function<T>(T)
+ * Function()>.
+ * @description Checks that generic function can be a function type alias
+ * argument and bound.
+ * @author [email protected]
+ */
+//--enable-experiment=generic-metadata
+
+import "../../Utils/expect.dart";
+
+typedef T1<TT extends void Function<T>(T)> = TT Function();
+typedef T2<TT extends void Function<T>(T)> = void Function(TT);
+typedef T3<TT extends void Function<T>(T)> = TT Function(TT);
+typedef T4<TT extends void Function<T>(T)> = void Function<TTT extends TT>();
+typedef T5<TT extends void Function<T>(T)> = TTT Function<TTT extends TT>(TTT);
+typedef T6<TT extends void Function<T>(T)> = void Function();
+
+typedef exp1 = void Function<T>(T) Function();
+typedef exp2 = void Function(void Function<T>(T));
+typedef exp3 = void Function<T>(T) Function(void Function<T>(T));
+typedef exp4 = void Function<T extends void Function<T>(T)>();
+typedef exp5 = T Function<T extends void Function<T>(T)>(T);
+typedef exp6 = void Function();
+
+main() {
+  Expect.equals(exp1, T1);
+  Expect.equals(exp2, T2);
+  Expect.equals(exp3, T3);
+  Expect.equals(exp4, T4);
+  Expect.equals(exp5, T5);
+  Expect.equals(exp6, T6);
+}

LanguageFeatures/Generic-functions-as-type-args/typedef1_A02_t03.dart

@@ -0,0 +1,61 @@
+/*
+ * Copyright (c) 2021, 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.
+ */
+/**
+ * @assertion Allow generic function types as type arguments and bounds
+ *
+ * The language disallows generic function types as type arguments and bounds.
+ *
+ *  late List<T Function<T>(T)> idFunctions; // INVALID.
+ *  var callback = [foo<T>(T value) => value]; // Inferred as above, then invalid.
+ *  late S Function<S extends T Function<T>(T)>(S) f; // INVALID.
+ *
+ * We remove that restriction, so a type argument and a bound can be a generic
+ * function type.
+ *
+ * This requires no new syntax, and in some cases only the removal of a single
+ * check. There might be some platforms where the implementation currently
+ * assumes that generic function types cannot occur as the value of type
+ * variables (an proof-of-concept attempt hit an assert in the VM). Such
+ * assumptions will need to be flushed out with tests and fixed.
+ *
+ * Because we already infer List<T Function<T>(T)> in the code above, this
+ * change will not affect type inference, it will just make the inferred type
+ * not be an error afterwards.
+ *
+ * We do not expect the removal of this restriction to affect the feasibility of
+ * type inference. After all, it's already possible to have a generic function
+ * type occurring covariantly in a type argument, like List<T Function<T>(T)
+ * Function()>.
+ * @description Checks that generic function can be a function type alias
+ * argument and bound.
+ * @author [email protected]
+ */
+//--enable-experiment=generic-metadata
+
+import "../../Utils/expect.dart";
+
+typedef T1<TT extends T Function<T>()> = TT Function();
+typedef T2<TT extends T Function<T>()> = void Function(TT);
+typedef T3<TT extends T Function<T>()> = TT Function(TT);
+typedef T4<TT extends T Function<T>()> = void Function<TTT extends TT>();
+typedef T5<TT extends T Function<T>()> = TTT Function<TTT extends TT>(TTT);
+typedef T6<TT extends T Function<T>()> = void Function();
+
+typedef exp1 = T Function<T>() Function();
+typedef exp2 = void Function(T Function<T>());
+typedef exp3 = T Function<T>() Function(T Function<T>());
+typedef exp4 = void Function<T extends T Function<T>()>();
+typedef exp5 = T Function<T extends T Function<T>()>(T);
+typedef exp6 = void Function();
+
+main() {
+  Expect.equals(exp1, T1);
+  Expect.equals(exp2, T2);
+  Expect.equals(exp3, T3);
+  Expect.equals(exp4, T4);
+  Expect.equals(exp5, T5);
+  Expect.equals(exp6, T6);
+}

LanguageFeatures/Generic-functions-as-type-args/typedef1_A02_t04.dart

@@ -0,0 +1,61 @@
+/*
+ * Copyright (c) 2021, 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.
+ */
+/**
+ * @assertion Allow generic function types as type arguments and bounds
+ *
+ * The language disallows generic function types as type arguments and bounds.
+ *
+ *  late List<T Function<T>(T)> idFunctions; // INVALID.
+ *  var callback = [foo<T>(T value) => value]; // Inferred as above, then invalid.
+ *  late S Function<S extends T Function<T>(T)>(S) f; // INVALID.
+ *
+ * We remove that restriction, so a type argument and a bound can be a generic
+ * function type.
+ *
+ * This requires no new syntax, and in some cases only the removal of a single
+ * check. There might be some platforms where the implementation currently
+ * assumes that generic function types cannot occur as the value of type
+ * variables (an proof-of-concept attempt hit an assert in the VM). Such
+ * assumptions will need to be flushed out with tests and fixed.
+ *
+ * Because we already infer List<T Function<T>(T)> in the code above, this
+ * change will not affect type inference, it will just make the inferred type
+ * not be an error afterwards.
+ *
+ * We do not expect the removal of this restriction to affect the feasibility of
+ * type inference. After all, it's already possible to have a generic function
+ * type occurring covariantly in a type argument, like List<T Function<T>(T)
+ * Function()>.
+ * @description Checks that generic function can be a function type alias
+ * argument and bound.
+ * @author [email protected]
+ */
+//--enable-experiment=generic-metadata
+
+import "../../Utils/expect.dart";
+
+typedef T1<TT extends void Function<T>()> = TT Function();
+typedef T2<TT extends void Function<T>()> = void Function(TT);
+typedef T3<TT extends void Function<T>()> = TT Function(TT);
+typedef T4<TT extends void Function<T>()> = void Function<TTT extends TT>();
+typedef T5<TT extends void Function<T>()> = TTT Function<TTT extends TT>(TTT);
+typedef T6<TT extends void Function<T>()> = void Function();
+
+typedef exp1 = void Function<T>() Function();
+typedef exp2 = void Function(void Function<T>());
+typedef exp3 = void Function<T>() Function(void Function<T>());
+typedef exp4 = void Function<T extends void Function<T>()>();
+typedef exp5 = T Function<T extends void Function<T>()>(T);
+typedef exp6 = void Function();
+
+main() {
+  Expect.equals(exp1, T1);
+  Expect.equals(exp2, T2);
+  Expect.equals(exp3, T3);
+  Expect.equals(exp4, T4);
+  Expect.equals(exp5, T5);
+  Expect.equals(exp6, T6);
+}

LanguageFeatures/Generic-functions-as-type-args/typedef2_A02_t01.dart

@@ -0,0 +1,52 @@
+/*
+ * Copyright (c) 2021, 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.
+ */
+/**
+ * @assertion Allow generic function types as type arguments and bounds
+ *
+ * The language disallows generic function types as type arguments and bounds.
+ *
+ *  late List<T Function<T>(T)> idFunctions; // INVALID.
+ *  var callback = [foo<T>(T value) => value]; // Inferred as above, then invalid.
+ *  late S Function<S extends T Function<T>(T)>(S) f; // INVALID.
+ *
+ * We remove that restriction, so a type argument and a bound can be a generic
+ * function type.
+ *
+ * This requires no new syntax, and in some cases only the removal of a single
+ * check. There might be some platforms where the implementation currently
+ * assumes that generic function types cannot occur as the value of type
+ * variables (an proof-of-concept attempt hit an assert in the VM). Such
+ * assumptions will need to be flushed out with tests and fixed.
+ *
+ * Because we already infer List<T Function<T>(T)> in the code above, this
+ * change will not affect type inference, it will just make the inferred type
+ * not be an error afterwards.
+ *
+ * We do not expect the removal of this restriction to affect the feasibility of
+ * type inference. After all, it's already possible to have a generic function
+ * type occurring covariantly in a type argument, like List<T Function<T>(T)
+ * Function()>.
+ * @description Checks that generic function can be a function type alias
+ * argument and bound.
+ * @author [email protected]
+ */
+//--enable-experiment=generic-metadata
+
+import "../../Utils/expect.dart";
+
+typedef void TEST1<T extends void Function<TT>()>();
+typedef void TEST2<T extends TT Function<TT>()>();
+typedef void TEST3<T extends void Function<TT>(TT)>();
+typedef void TEST4<T extends TT Function<TT>(TT)>();
+
+typedef exp = void Function();
+
+main() {
+  Expect.equals(exp, TEST1);
+  Expect.equals(exp, TEST2);
+  Expect.equals(exp, TEST3);
+  Expect.equals(exp, TEST4);
+}

LanguageFeatures/Generic-functions-as-type-args/typedef2_A02_t02.dart

@@ -0,0 +1,55 @@
+/*
+ * Copyright (c) 2021, 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.
+ */
+/**
+ * @assertion Allow generic function types as type arguments and bounds
+ *
+ * The language disallows generic function types as type arguments and bounds.
+ *
+ *  late List<T Function<T>(T)> idFunctions; // INVALID.
+ *  var callback = [foo<T>(T value) => value]; // Inferred as above, then invalid.
+ *  late S Function<S extends T Function<T>(T)>(S) f; // INVALID.
+ *
+ * We remove that restriction, so a type argument and a bound can be a generic
+ * function type.
+ *
+ * This requires no new syntax, and in some cases only the removal of a single
+ * check. There might be some platforms where the implementation currently
+ * assumes that generic function types cannot occur as the value of type
+ * variables (an proof-of-concept attempt hit an assert in the VM). Such
+ * assumptions will need to be flushed out with tests and fixed.
+ *
+ * Because we already infer List<T Function<T>(T)> in the code above, this
+ * change will not affect type inference, it will just make the inferred type
+ * not be an error afterwards.
+ *
+ * We do not expect the removal of this restriction to affect the feasibility of
+ * type inference. After all, it's already possible to have a generic function
+ * type occurring covariantly in a type argument, like List<T Function<T>(T)
+ * Function()>.
+ * @description Checks that generic function can be a function type alias
+ * argument and bound.
+ * @author [email protected]
+ */
+//--enable-experiment=generic-metadata
+
+import "../../Utils/expect.dart";
+
+typedef T TEST1<T extends void Function<TT>()>();
+typedef T TEST2<T extends TT Function<TT>()>();
+typedef T TEST3<T extends void Function<TT>(TT)>();
+typedef T TEST4<T extends TT Function<TT>(TT)>();
+
+typedef exp1 = void Function<T>() Function();
+typedef exp2 = T Function<T>() Function();
+typedef exp3 = void Function<T>(T) Function();
+typedef exp4 = T Function<T>(T) Function();
+
+main() {
+  Expect.equals(exp1, TEST1);
+  Expect.equals(exp2, TEST2);
+  Expect.equals(exp3, TEST3);
+  Expect.equals(exp4, TEST4);
+}