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Source file test/alias2.go

Documentation: test

     1  // errorcheck
     2  
     3  // Copyright 2016 The Go Authors. All rights reserved.
     4  // Use of this source code is governed by a BSD-style
     5  // license that can be found in the LICENSE file.
     6  
     7  // Test basic restrictions on type aliases.
     8  
     9  package p
    10  
    11  import (
    12  	"reflect"
    13  	. "reflect"
    14  )
    15  
    16  type T0 struct{}
    17  
    18  // Valid type alias declarations.
    19  
    20  type _ = T0
    21  type _ = int
    22  type _ = struct{}
    23  type _ = reflect.Value
    24  type _ = Value
    25  
    26  type (
    27  	A0 = T0
    28  	A1 = int
    29  	A2 = struct{}
    30  	A3 = reflect.Value
    31  	A4 = Value
    32  	A5 = Value
    33  
    34  	N0 A0
    35  )
    36  
    37  // Methods can be declared on the original named type and the alias.
    38  func (T0) m1()  {} // GCCGO_ERROR "previous"
    39  func (*T0) m1() {} // ERROR "method redeclared: T0\.m1|redefinition of .m1."
    40  func (A0) m1()  {} // ERROR "T0\.m1 redeclared in this block|redefinition of .m1."
    41  func (A0) m1()  {} // ERROR "T0\.m1 redeclared in this block|redefinition of .m1."
    42  func (A0) m2()  {}
    43  
    44  // Type aliases and the original type name can be used interchangeably.
    45  var _ A0 = T0{}
    46  var _ T0 = A0{}
    47  
    48  // But aliases and original types cannot be used with new types based on them.
    49  var _ N0 = T0{} // ERROR "cannot use T0 literal \(type T0\) as type N0 in assignment|incompatible type"
    50  var _ N0 = A0{} // ERROR "cannot use T0 literal \(type T0\) as type N0 in assignment|incompatible type"
    51  
    52  var _ A5 = Value{}
    53  
    54  var _ interface {
    55  	m1()
    56  	m2()
    57  } = T0{}
    58  
    59  var _ interface {
    60  	m1()
    61  	m2()
    62  } = A0{}
    63  
    64  func _() {
    65  	type _ = T0
    66  	type _ = int
    67  	type _ = struct{}
    68  	type _ = reflect.Value
    69  	type _ = Value
    70  
    71  	type (
    72  		A0 = T0
    73  		A1 = int
    74  		A2 = struct{}
    75  		A3 = reflect.Value
    76  		A4 = Value
    77  		A5 Value
    78  
    79  		N0 A0
    80  	)
    81  
    82  	var _ A0 = T0{}
    83  	var _ T0 = A0{}
    84  
    85  	var _ N0 = T0{} // ERROR "cannot use T0 literal \(type T0\) as type N0 in assignment|incompatible type"
    86  	var _ N0 = A0{} // ERROR "cannot use T0 literal \(type T0\) as type N0 in assignment|incompatible type"
    87  
    88  	var _ A5 = Value{} // ERROR "cannot use reflect\.Value literal \(type reflect.Value\) as type A5 in assignment|incompatible type"
    89  }
    90  
    91  // Invalid type alias declarations.
    92  
    93  type _ = reflect.ValueOf // ERROR "reflect.ValueOf is not a type|expected type"
    94  
    95  func (A1) m() {} // ERROR "cannot define new methods on non-local type int|may not define methods on non-local type"
    96  func (A2) m() {} // ERROR "invalid receiver type"
    97  func (A3) m() {} // ERROR "cannot define new methods on non-local type reflect.Value|may not define methods on non-local type"
    98  func (A4) m() {} // ERROR "cannot define new methods on non-local type reflect.Value|may not define methods on non-local type"
    99  
   100  type B1 = struct{}
   101  
   102  func (B1) m() {} // ERROR "invalid receiver type"
   103  
   104  // TODO(gri) expand
   105  

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