issue49179.go

     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  func f1[P int | string]()            {}
     8  func f2[P ~int | string | float64]() {}
     9  func f3[P int](x P)                  {}
    10  
    11  type myInt int
    12  type myFloat float64
    13  
    14  func _() {
    15  	_ = f1[int]
    16  	_ = f1[myInt /* ERROR "possibly missing ~ for int in int | string" */]
    17  	_ = f2[myInt]
    18  	_ = f2[myFloat /* ERROR "possibly missing ~ for float64 in ~int | string | float64" */]
    19  	var x myInt
    20  	f3 /* ERROR "myInt does not satisfy int (possibly missing ~ for int in int)" */ (x)
    21  }
    22  
    23  // test case from the issue
    24  
    25  type SliceConstraint[T any] interface {
    26  	[]T
    27  }
    28  
    29  func Map[S SliceConstraint[E], E any](s S, f func(E) E) S {
    30  	return s
    31  }
    32  
    33  type MySlice []int
    34  
    35  func f(s MySlice) {
    36  	Map[MySlice /* ERROR "MySlice does not satisfy SliceConstraint[int] (possibly missing ~ for []int in SliceConstraint[int])" */, int](s, nil)
    37  }
    38
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