issue49482.go

     1  // Copyright 2022 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  // The following is OK, per the special handling for type literals discussed in issue #49482.
     8  type _[P *struct{}] struct{}
     9  type _[P *int,] int
    10  type _[P (*int),] int
    11  
    12  const P = 2 // declare P to avoid noisy 'undefined' errors below.
    13  
    14  // The following parse as invalid array types due to parsing ambiguitiues.
    15  type _ [P *int /* ERROR "int (type) is not an expression" */ ]int
    16  type _ [P /* ERROR "non-function P" */ (*int)]int
    17  
    18  // Adding a trailing comma or an enclosing interface resolves the ambiguity.
    19  type _[P *int,] int
    20  type _[P (*int),] int
    21  type _[P interface{*int}] int
    22  type _[P interface{(*int)}] int
    23  
    24  // The following parse correctly as valid generic types.
    25  type _[P *struct{} | int] struct{}
    26  type _[P *struct{} | ~int] struct{}
    27
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