// 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.

// @dart = 2.9

/// @assertion A type T0 is a subtype of a type T1 (written T0 <: T1) when:
/// Positional Function Types: T0 is U0 Function<X0 extends B00, ... ,
/// Xk extends B0k>(V0 x0, ..., Vn xn, [Vn+1 xn+1, ..., Vm xm])
///
///  and T1 is U1 Function<Y0 extends B10, ..., Yk extends B1k>(S0 y0, ...,
///  Sp yp, [Sp+1 yp+1, ..., Sq yq])
///  and p >= n
///  and m >= q
///  and Si[Z0/Y0, ..., Zk/Yk] <: Vi[Z0/X0, ..., Zk/Xk] for i in 0...q
///  and U0[Z0/X0, ..., Zk/Xk] <: U1[Z0/Y0, ..., Zk/Yk]
///  and B0i[Z0/X0, ..., Zk/Xk] === B1i[Z0/Y0, ..., Zk/Yk] for i in 0...k
///  where the Zi are fresh type variables with bounds B0i[Z0/X0, ..., Zk/Xk]
///
/// @description Check that if T0 isn't a subtype of T1 if Si[Z0/Y0, ..., Zk/Yk]
/// isn't a subtype of Vi[Z0/X0, ..., Zk/Xk] for any i in 0...q.
/// @author sgrekhov@unipro.ru
/// @author ngl@unipro.ru


class U0 extends U1 {}
class U1 {}
class V0 {}
class V1 {}
class V2 {}
class V3 {}
class S0 extends V0 {}
class S1 extends V1 {}
class S2 {}
class S3 extends V3 {}

typedef T0 = U0 Function(V0 x0, V1 x1, [V2 x2, V3 x3]);
typedef T1 = U1 Function(S0 y0, S1 y1, [S2 y2, S3 y3]);

U0 t0Func(V0 x0, V1 x1, [V2 x2, V3 x3]) => null;
U1 t1Func(S0 y0, S1 y1, [S2 y2, S3 y3]) => null;

T0 t0Instance = t0Func;
T1 t1Instance = t1Func;
//# @T0 = T0
//# @T1 = T1