issue67547.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  func _[P int]() {
     8  	type A = P
     9  	_ = A(0) // don't crash with this conversion
    10  }
    11  
    12  func _[P []int]() {
    13  	type A = P
    14  	_ = make(A, 10) // don't report an error for A
    15  }
    16  
    17  func _[P string]() {
    18  	var t []byte
    19  	type A = P
    20  	var s A
    21  	copy(t, s) // don't report an error for s
    22  }
    23  
    24  func _[P map[int]int]() {
    25  	type A = P
    26  	var m A
    27  	clear(m) // don't report an error for m
    28  }
    29  
    30  type S1 struct {
    31  	x int "S1.x"
    32  }
    33  
    34  type S2 struct {
    35  	x int "S2.x"
    36  }
    37  
    38  func _[P1 S1, P2 S2]() {
    39  	type A = P1
    40  	var p A
    41  	_ = P2(p) // conversion must be valid
    42  }
    43  
    44  func _[P1 S1, P2 S2]() {
    45  	var p P1
    46  	type A = P2
    47  	_ = A(p) // conversion must be valid
    48  }
    49  
    50  func _[P int | string]() {
    51  	var p P
    52  	type A = int
    53  	// preserve target type name A in error messages when using Alias types
    54  	// (test are run with and without Alias types enabled, so we need to
    55  	// keep both A and int in the error message)
    56  	_ = A(p /* ERRORx `cannot convert string \(in P\) to type (A|int)` */)
    57  }
    58  
    59  func _[P struct{ x int }]() {
    60  	var x struct{ x int }
    61  	type A = P
    62  	var _ A = x // assignment must be valid
    63  }
    64  
    65  func _[P struct{ x int }]() {
    66  	type A = P
    67  	var x A
    68  	var _ struct{ x int } = x // assignment must be valid
    69  }
    70  
    71  func _[P []int | struct{}]() {
    72  	type A = []int
    73  	var a A
    74  	var p P
    75  	// preserve target type name A in error messages when using Alias types
    76  	a = p // ERRORx `cannot assign struct{} \(in P\) to (A|\[\]int)`
    77  	_ = a
    78  }
    79  
    80  func _[P any]() {
    81  	type A = P
    82  	var x A
    83  	// keep "constrained by" for aliased type parameters in error messages
    84  	var _ int = x // ERRORx `cannot use x \(variable of type (A|P) constrained by any\) as int value in variable declaration`
    85  }
    86  
    87  // Test case for go.dev/issue/67540.
    88  func _() {
    89  	type (
    90  		S struct{}
    91  		A = *S
    92  		T S
    93  	)
    94  	var p A
    95  	_ = (*T)(p)
    96  }
    97
View as plain text