1// Copyright 2022 The Go Authors. All rights reserved. 2// Use of this source code is governed by a BSD-style 3// license that can be found in the LICENSE file. 4 5package b 6 7import "./a" 8 9type ( 10 lA[P any] [10]P 11 lS[P any] struct{ f P } 12 lP[P any] *P 13 lM[K comparable, V any] map[K]V 14) 15 16// local cycles 17type ( 18 A lA[A] // ERROR "invalid recursive type" 19 S lS[S] // ERROR "invalid recursive type" 20 P lP[P] // ok (indirection through lP) 21 M1 lM[int, M1] // ok (indirection through lM) 22 M2 lM[lA[byte], M2] // ok (indirection through lM) 23 24 A2 lA[lS[lP[A2]]] // ok (indirection through lP) 25 A3 lA[lS[lS[A3]]] // ERROR "invalid recursive type" 26) 27 28// cycles through imported types 29type ( 30 Ai a.A[Ai] // ERROR "invalid recursive type" 31 Si a.S[Si] // ERROR "invalid recursive type" 32 Pi a.P[Pi] // ok (indirection through a.P) 33 M1i a.M[int, M1i] // ok (indirection through a.M) 34 M2i a.M[a.A[byte], M2i] // ok (indirection through a.M) 35 36 A2i a.A[a.S[a.P[A2i]]] // ok (indirection through a.P) 37 A3i a.A[a.S[a.S[A3i]]] // ERROR "invalid recursive type" 38 39 T2 a.S[T0[T2]] // ERROR "invalid recursive type" 40 T3 T0[Ai] // no follow-on error here 41) 42 43// test case from issue 44 45type T0[P any] struct { 46 f P 47} 48 49type T1 struct { // ERROR "invalid recursive type" 50 _ T0[T1] 51} 52