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

…added.

LanguageFeatures/Generic-functions-as-type-args/typedef2_t01.dart

@@ -0,0 +1,47 @@
+/*
+ * 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.
+ * @Issue 45313
+ * @author [email protected]
+ */
+//--enable-experiment=generic-metadata
+
+import "../../Utils/expect.dart";
+
+typedef void TEST<T extends void Function<TT>()>();
+void testme<T extends void Function<TT>()>() {}
+
+main() {
+  TEST t = testme;
+  Expect.isTrue(testme is TEST);
+}

LanguageFeatures/Generic-functions-as-type-args/typedef2_t02.dart

@@ -0,0 +1,47 @@
+/*
+ * 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.
+ * @Issue 45313
+ * @author [email protected]
+ */
+//--enable-experiment=generic-metadata
+
+import "../../Utils/expect.dart";
+
+typedef void TEST<T extends TT Function<TT>()>();
+void testme<T extends TT Function<TT>()>() {}
+
+main() {
+  TEST t = testme;
+  Expect.isTrue(testme is TEST);
+}

LanguageFeatures/Generic-functions-as-type-args/typedef2_t03.dart

@@ -0,0 +1,47 @@
+/*
+ * 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.
+ * @Issue 45313, 45322
+ * @author [email protected]
+ */
+//--enable-experiment=generic-metadata
+
+import "../../Utils/expect.dart";
+
+typedef void TEST<T extends void Function<TT>(TT t)>();
+void testme<T extends void Function<TT>(TT t)>() {}
+
+main() {
+  TEST t = testme;
+  Expect.isTrue(testme is TEST);
+}

LanguageFeatures/Generic-functions-as-type-args/typedef2_t04.dart

@@ -0,0 +1,47 @@
+/*
+ * 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.
+ * @Issue 45313, 45322
+ * @author [email protected]
+ */
+//--enable-experiment=generic-metadata
+
+import "../../Utils/expect.dart";
+
+typedef void TEST<T extends TT Function<TT>(TT t)>();
+void testme<T extends TT Function<TT>(TT t)>() {}
+
+main() {
+  TEST t = testme;
+  Expect.isTrue(testme is TEST);
+}

LanguageFeatures/Generic-functions-as-type-args/typedef2_t05.dart

@@ -0,0 +1,47 @@
+/*
+ * 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.
+ * @Issue 45313
+ * @author [email protected]
+ */
+//--enable-experiment=generic-metadata
+
+import "../../Utils/expect.dart";
+
+typedef T TEST<T extends void Function<TT>()>();
+T testme<T extends void Function<TT>()>() => throw "Hello";
+
+main() {
+  TEST t = testme;
+  Expect.isTrue(testme is TEST);
+}

LanguageFeatures/Generic-functions-as-type-args/typedef2_t06.dart

@@ -0,0 +1,47 @@
+/*
+ * 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.
+ * @Issue 45313
+ * @author [email protected]
+ */
+//--enable-experiment=generic-metadata
+
+import "../../Utils/expect.dart";
+
+typedef T TEST<T extends TT Function<TT>()>();
+T testme<T extends TT Function<TT>()>() => throw "Hello!";
+
+main() {
+  TEST t = testme;
+  Expect.isTrue(testme is TEST);
+}

LanguageFeatures/Generic-functions-as-type-args/typedef2_t07.dart

@@ -0,0 +1,47 @@
+/*
+ * 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.
+ * @Issue 45313, 45322
+ * @author [email protected]
+ */
+//--enable-experiment=generic-metadata
+
+import "../../Utils/expect.dart";
+
+typedef T TEST<T extends void Function<TT>(TT t)>();
+T testme<T extends void Function<TT>(TT t)>() => throw "Hello!";
+
+main() {
+  TEST t = testme;
+  Expect.isTrue(testme is TEST);
+}

LanguageFeatures/Generic-functions-as-type-args/typedef2_t08.dart

@@ -0,0 +1,47 @@
+/*
+ * 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.
+ * @Issue 45313, 45322
+ * @author [email protected]
+ */
+//--enable-experiment=generic-metadata
+
+import "../../Utils/expect.dart";
+
+typedef T TEST<T extends void Function<TT>(TT t)>();
+T testme<T extends void Function<TT>(TT t)>() => throw "Hello!";
+
+main() {
+  TEST t = testme;
+  Expect.isTrue(testme is TEST);
+}