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b2386dffa1
Known issues: - needs many more tests - duplicate method declarations via type alias names are not detected - type alias cycle error messages need to be improved - need to review setup of byte/rune type aliases For #18130. Change-Id: Icc2fefad6214e5e56539a9dcb3fe537bf58029f8 Reviewed-on: https://go-review.googlesource.com/35121 Run-TryBot: Robert Griesemer <gri@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Matthew Dempsky <mdempsky@google.com>
100 lines
1.9 KiB
Go
100 lines
1.9 KiB
Go
// errorcheck
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// Copyright 2016 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Test basic restrictions on type aliases.
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package p
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import (
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"reflect"
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. "reflect"
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)
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type T0 struct{}
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// Valid type alias declarations.
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type _ = T0
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type _ = int
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type _ = struct{}
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type _ = reflect.Value
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type _ = Value
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type (
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A0 = T0
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A1 = int
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A2 = struct{}
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A3 = reflect.Value
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A4 = Value
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A5 = Value
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N0 A0
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)
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// Methods can be declared on the original named type and the alias.
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func (T0) m1() {}
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func (A0) m1() {} // TODO(gri) this should be an error
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func (A0) m2() {}
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// Type aliases and the original type name can be used interchangeably.
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var _ A0 = T0{}
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var _ T0 = A0{}
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// But aliases and original types cannot be used with new types based on them.
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var _ N0 = T0{} // ERROR "cannot use T0 literal \(type T0\) as type N0 in assignment"
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var _ N0 = A0{} // ERROR "cannot use T0 literal \(type T0\) as type N0 in assignment"
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var _ A5 = Value{}
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var _ interface {
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m1()
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m2()
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} = T0{}
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var _ interface {
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m1()
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m2()
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} = A0{}
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func _() {
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type _ = T0
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type _ = int
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type _ = struct{}
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type _ = reflect.Value
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type _ = Value
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type (
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A0 = T0
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A1 = int
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A2 = struct{}
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A3 = reflect.Value
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A4 = Value
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A5 Value
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N0 A0
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)
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var _ A0 = T0{}
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var _ T0 = A0{}
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var _ N0 = T0{} // ERROR "cannot use T0 literal \(type T0\) as type N0 in assignment"
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var _ N0 = A0{} // ERROR "cannot use T0 literal \(type T0\) as type N0 in assignment"
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var _ A5 = Value{} // ERROR "cannot use reflect\.Value literal \(type reflect.Value\) as type A5 in assignment"
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}
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// Invalid type alias declarations.
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type _ = reflect.ValueOf // ERROR "reflect.ValueOf is not a type"
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func (A1) m() {} // ERROR "cannot define new methods on non-local type int"
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type B1 = struct{}
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func (B1) m() {} // ERROR "invalid receiver type"
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// TODO(gri) expand
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