// 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 // For now, a lone type parameter is not permitted as RHS in a type declaration (issue #45639). // type T1[P any] P // // func (T1[_]) m() {} // // func _[P any](x *T1[P]) { // // x.m exists because x is of type *T1 where T1 is a defined type // // (even though under(T1) is a type parameter) // x.m() // } func _[P interface{ m() }](x P) { x.m() // (&x).m doesn't exist because &x is of type *P // and pointers to type parameters don't have methods (&x).m /* ERROR type \*P is pointer to type parameter, not type parameter */ () } type T2 interface{ m() } func _(x *T2) { // x.m doesn't exists because x is of type *T2 // and pointers to interfaces don't have methods x.m /* ERROR type \*T2 is pointer to interface, not interface */() } // Test case 1 from issue type Fooer1[t any] interface { Foo(Barer[t]) } type Barer[t any] interface { Bar(t) } // For now, a lone type parameter is not permitted as RHS in a type declaration (issue #45639). // type Foo1[t any] t // type Bar[t any] t // // func (l Foo1[t]) Foo(v Barer[t]) { v.Bar(t(l)) } // func (b *Bar[t]) Bar(l t) { *b = Bar[t](l) } // // func _[t any](f Fooer1[t]) t { // var b Bar[t] // f.Foo(&b) // return t(b) // } // Test case 2 from issue // For now, a lone type parameter is not permitted as RHS in a type declaration (issue #45639). // type Fooer2[t any] interface { // Foo() // } // // type Foo2[t any] t // // func (f *Foo2[t]) Foo() {} // // func _[t any](v t) { // var f = Foo2[t](v) // _ = Fooer2[t](&f) // }