| // Copyright 2021 The Go Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style |
| // license that can be found in the LICENSE file. |
| |
| package p |
| |
| type C0 interface{ int } |
| type C1 interface{ chan int } |
| type C2 interface{ chan int | <-chan int } |
| type C3 interface{ chan int | chan float32 } |
| type C4 interface{ chan int | chan<- int } |
| type C5[T any] interface{ ~chan T | <-chan T } |
| |
| func _[T any](ch T) { |
| <-ch // ERROR cannot receive from ch .* no structural type |
| } |
| |
| func _[T C0](ch T) { |
| <-ch // ERROR cannot receive from non-channel ch |
| } |
| |
| func _[T C1](ch T) { |
| <-ch |
| } |
| |
| func _[T C2](ch T) { |
| <-ch |
| } |
| |
| func _[T C3](ch T) { |
| <-ch // ERROR cannot receive from ch .* no structural type |
| } |
| |
| func _[T C4](ch T) { |
| <-ch // ERROR cannot receive from send-only channel |
| } |
| |
| func _[T C5[X], X any](ch T, x X) { |
| x = <-ch |
| } |
| |
| // test case from issue, slightly modified |
| type RecvChan[T any] interface { |
| ~chan T | ~<-chan T |
| } |
| |
| func _[T any, C RecvChan[T]](ch C) T { |
| return <-ch |
| } |
| |
| func f[T any, C interface{ chan T }](ch C) T { |
| return <-ch |
| } |
| |
| func _(ch chan int) { |
| var x int = f(ch) // test constraint type inference for this case |
| _ = x |
| } |