blob: c51c674c06ed5d25d8866ac069ea8f8d3ac80f98 [file] [log] [blame]
// 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.
// SharedOptions=--enable-experiment=generic-metadata
import "package:expect/expect.dart";
import "../static_type_helper.dart";
// Check that generic function types can be used as type arguments.
typedef F = T Function<T>(T);
class C<T> {
final T value;
const C(this.value);
}
T f<T>(T value) => value;
extension E<T> on T {
T get extensionValue => this;
}
// A generic function type can be a type parameter bound.
// For a type alias:
typedef FB<T extends F> = S Function<S extends T>(S);
// For a class:
class CB<T extends F> {
final T function;
const CB(this.function);
}
// For a function:
T fb<T extends F>(T value) => value;
extension EB<T extends F> on T {
T get boundExtensionValue => this;
// Any function type has a `call` of its own type?
T get boundCall => this.call;
}
// Can be used as arguments to metadata too.
@C<F>(f)
@CB<FB<F>>(fb)
void main() {
// Sanity checks.
Expect.type<F>(f);
Expect.type<FB<F>>(fb);
// A generic function type can be the argument to a generic class.
var list = [f]; // Inferred from content.
Expect.type<List<F>>(list);
list = []; // Inferred from context.
list.add(f);
list = <F>[]; // Explicit.
list.add(f);
// Also if the type has a bound.
var list2 = [fb];
Expect.type<List<FB<F>>>(list2);
// The instance is a subtype of its supertypes.
Expect.type<List<Function>>(list);
Expect.type<List<Object? Function<T>(Never)>>(list);
Expect.notType<List<Object? Function(Never)>>(list);
// A generic function type can be the argument to a generic function.
var g1 = f(f); // inferred from argument.
g1 = f(f); // Inferred from context.
g1 = f<F>(f); // Explicit.
g1.expectStaticType<Exactly<F>>();
// Extensions can match generic function types.
list.add(f.extensionValue);
list.add(E(f).extensionValue);
list.add(E<F>(f).extensionValue);
list.add(f.boundExtensionValue);
list.add(EB(f).boundExtensionValue);
list.add(EB<F>(f).boundExtensionValue);
list.add(f.boundCall);
list.add(EB(f).boundCall);
list.add(EB<F>(f).boundCall);
list2.add(fb.extensionValue);
list2.add(E(fb).extensionValue);
list2.add(E<FB<F>>(fb).extensionValue);
}