// 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.

/// @assertion A type T0 is a subtype of a type T1 (written T0 <: T1) when:
/// Named Function Types: T0 is U0 Function<X0 extends B00, ..., Xk extends B0k>
///   (T0 x0, ..., Tn xn, {Tn+1 xn+1, ..., Tm xm})
///
/// and T1 is U1 Function<Y0 extends B10, ..., Yk extends B1k>(S0 y0, ..., Sn yn,
/// {Sn+1 yn+1, ..., Sq yq})
/// and {yn+1, ... , yq} subsetof {xn+1, ... , xm}
/// and Si[Z0/Y0, ..., Zk/Yk] <: Vi[Z0/X0, ..., Zk/Xk] for i in 0...n
/// and Si[Z0/Y0, ..., Zk/Yk] <: Tj[Z0/X0, ..., Zk/Xk] for i in n+1...q, yj = xi
/// 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 there is i in 0...n such that
/// Si[Z0/Y0, ..., Zk/Yk] is not subtype of Vi[Z0/X0, ..., Zk/Xk], then T0 is not
/// a subtype of T1
/// @author sgrekhov@unipro.ru

class U0 extends U1 {}
class U1 {}
class V0 {}
class V1 {}
class V2 {}
class V3 {}
class V4 {}
class S0 extends V0 {}
class S1 {}
class S2 extends V2 {}
class S3 extends V3 {}

typedef T0 = U0 Function(V0 x0, V1 x1, {V2? x2, V3? x3, V4? x4});
typedef T1 = U1 Function(S0 y0, S1 y1, {S2? x2, S3? x3}); // S1 is not subtype of V1

U0 t0Func(V0 x0, V1 x1, {V2? x2, V3? x3, V4? x4}) => new U0();
U1 t1Func(S0 y0, S1 y1, {S2? x2, S3? x3}) => new U1();

T0 t0Instance = t0Func;
T1 t1Instance = t1Func;

const t1Default = t1Func;

//# @T0 = T0
//# @T1 = T1
//# @GenericFunctionType