| Dan Willemsen | bc60c3c | 2021-12-15 01:09:00 -0800 | [diff] [blame] | 1 | // Copyright 2021 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 | |
| 5 | package p |
| 6 | |
| 7 | // parameterized types with self-recursive constraints |
| 8 | type ( |
| 9 | T1 /* ERROR illegal cycle */ [P T1[P]] interface{} |
| 10 | T2 /* ERROR illegal cycle */ [P, Q T2[P, Q]] interface{} |
| 11 | T3[P T2[P, Q], Q interface{ ~string }] interface{} |
| 12 | |
| 13 | T4a /* ERROR illegal cycle */ [P T4a[P]] interface{ ~int } |
| 14 | T4b /* ERROR illegal cycle */ [P T4b[int]] interface{ ~int } |
| 15 | T4c /* ERROR illegal cycle */ [P T4c[string]] interface{ ~int } |
| 16 | |
| 17 | // mutually recursive constraints |
| 18 | T5 /* ERROR illegal cycle */ [P T6[P]] interface{ int } |
| 19 | T6[P T5[P]] interface{ int } |
| 20 | ) |
| 21 | |
| 22 | // verify that constraints are checked as expected |
| 23 | var ( |
| 24 | _ T1[int] |
| 25 | _ T2[int, string] |
| 26 | _ T3[int, string] |
| 27 | ) |
| 28 | |
| 29 | // test case from issue |
| 30 | |
| 31 | type Eq /* ERROR illegal cycle */ [a Eq[a]] interface { |
| 32 | Equal(that a) bool |
| 33 | } |