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 // For now, a lone type parameter is not permitted as RHS in a type declaration (issue #45639).
8 // type T1[P any] P
9 //
10 // func (T1[_]) m() {}
11 //
12 // func _[P any](x *T1[P]) {
13 // // x.m exists because x is of type *T1 where T1 is a defined type
14 // // (even though under(T1) is a type parameter)
15 // x.m()
16 // }
17
18
19 func _[P interface{ m() }](x P) {
20 x.m()
21 // (&x).m doesn't exist because &x is of type *P
22 // and pointers to type parameters don't have methods
23 (&x).m /* ERROR type \*P is pointer to type parameter, not type parameter */ ()
24 }
25
26
27 type T2 interface{ m() }
28
29 func _(x *T2) {
30 // x.m doesn't exists because x is of type *T2
31 // and pointers to interfaces don't have methods
32 x.m /* ERROR type \*T2 is pointer to interface, not interface */()
33 }
34
35 // Test case 1 from issue
36
37 type Fooer1[t any] interface {
38 Foo(Barer[t])
39 }
40 type Barer[t any] interface {
41 Bar(t)
42 }
43
44 // For now, a lone type parameter is not permitted as RHS in a type declaration (issue #45639).
45 // type Foo1[t any] t
46 // type Bar[t any] t
47 //
48 // func (l Foo1[t]) Foo(v Barer[t]) { v.Bar(t(l)) }
49 // func (b *Bar[t]) Bar(l t) { *b = Bar[t](l) }
50 //
51 // func _[t any](f Fooer1[t]) t {
52 // var b Bar[t]
53 // f.Foo(&b)
54 // return t(b)
55 // }
56
57 // Test case 2 from issue
58
59 // For now, a lone type parameter is not permitted as RHS in a type declaration (issue #45639).
60 // type Fooer2[t any] interface {
61 // Foo()
62 // }
63 //
64 // type Foo2[t any] t
65 //
66 // func (f *Foo2[t]) Foo() {}
67 //
68 // func _[t any](v t) {
69 // var f = Foo2[t](v)
70 // _ = Fooer2[t](&f)
71 // }
72
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