issue70417.go

     1  // Copyright 2024 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  type T[P any] struct{}
     8  
     9  // A0
    10  type A0 = T[int]
    11  type B0 = *T[int]
    12  
    13  func (A0 /* ERROR "cannot define new methods on instantiated type T[int]" */) m()  {}
    14  func (*A0 /* ERROR "cannot define new methods on instantiated type T[int]" */) m() {}
    15  func (B0 /* ERROR "cannot define new methods on instantiated type T[int]" */) m()  {}
    16  
    17  // A1
    18  type A1[P any] = T[P]
    19  type B1[P any] = *T[P]
    20  
    21  func (A1 /* ERROR "cannot define new methods on generic alias type A1[P any]" */ [P]) m()  {}
    22  func (*A1 /* ERROR "cannot define new methods on generic alias type A1[P any]" */ [P]) m() {}
    23  func (B1 /* ERROR "cannot define new methods on generic alias type B1[P any]" */ [P]) m()  {}
    24  
    25  // A2
    26  type A2[P any] = T[int]
    27  type B2[P any] = *T[int]
    28  
    29  func (A2 /* ERROR "cannot define new methods on generic alias type A2[P any]" */ [P]) m()  {}
    30  func (*A2 /* ERROR "cannot define new methods on generic alias type A2[P any]" */ [P]) m() {}
    31  func (B2 /* ERROR "cannot define new methods on generic alias type B2[P any]" */ [P]) m()  {}
    32  
    33  // A3
    34  type A3 = T[int]
    35  type B3 = *T[int]
    36  
    37  func (A3 /* ERROR "cannot define new methods on instantiated type T[int]" */) m()  {}
    38  func (*A3 /* ERROR "cannot define new methods on instantiated type T[int]" */) m() {}
    39  func (B3 /* ERROR "cannot define new methods on instantiated type T[int]" */) m()  {}
    40  
    41  // A4
    42  type A4 = T  // ERROR "cannot use generic type T[P any] without instantiation"
    43  type B4 = *T // ERROR "cannot use generic type T[P any] without instantiation"
    44  
    45  func (A4[P]) m1()  {} // don't report a follow-on error on A4
    46  func (*A4[P]) m2() {} // don't report a follow-on error on A4
    47  func (B4[P]) m3()  {} // don't report a follow-on error on B4
    48  
    49  // instantiation in the middle of an alias chain
    50  type S struct{}
    51  type C0 = S
    52  type C1[P any] = C0
    53  type C2 = *C1[int]
    54  
    55  func (C2 /* ERROR "cannot define new methods on instantiated type C1[int]" */) m()  {}
    56  func (*C2 /* ERROR "cannot define new methods on instantiated type C1[int]" */) m() {}
    57
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