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7398c3c0c6
Compromise between old compiler error "T.m redeclared in this block" (where the "in this block" is not particularly helpful) and the old type-checker error "method m already declared for type T ...". In the case where we have position information for the original declaration, the error message is "method T.m already declared at <position>". The new message is both shorter and more precise. For #55326. Change-Id: Id4a7f326fe631b11db9e8030eccb417c72d6c7db Reviewed-on: https://go-review.googlesource.com/c/go/+/435016 Run-TryBot: Robert Griesemer <gri@google.com> Auto-Submit: Robert Griesemer <gri@google.com> TryBot-Result: Gopher Robot <gobot@golang.org> Reviewed-by: Robert Griesemer <gri@google.com> Reviewed-by: Robert Findley <rfindley@google.com>
105 lines
2.8 KiB
Go
105 lines
2.8 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() {} // GCCGO_ERROR "previous"
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func (*T0) m1() {} // ERROR "method redeclared: T0\.m1|T0\.m1 already declared|redefinition of .m1."
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func (A0) m1() {} // ERROR "T0\.m1 already declared|redefinition of .m1."
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func (A0) m1() {} // ERROR "T0\.m1 already declared|redefinition of .m1."
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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{} \(type T0\) as type N0 in assignment|cannot use T0{} \(value of type T0\) as type N0 in variable declaration"
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var _ N0 = A0{} // ERROR "cannot use T0{} \(type T0\) as type N0 in assignment|cannot use A0{} \(value of type T0\) as type N0 in variable declaration"
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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{} \(type T0\) as type N0 in assignment|cannot use T0{} \(value of type T0\) as type N0 in variable declaration"
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var _ N0 = A0{} // ERROR "cannot use T0{} \(type T0\) as type N0 in assignment|cannot use A0{} \(value of type T0\) as type N0 in variable declaration"
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var _ A5 = Value{} // ERROR "cannot use reflect\.Value{} \(type reflect.Value\) as type A5 in assignment|cannot use Value{} \(value of type reflect.Value\) as type A5 in variable declaration"
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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|expected type"
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func (A1) m() {} // ERROR "cannot define new methods on non-local type int|may not define methods on non-local type"
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func (A2) m() {} // ERROR "invalid receiver type"
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func (A3) m() {} // ERROR "cannot define new methods on non-local type reflect.Value|may not define methods on non-local type"
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func (A4) m() {} // ERROR "cannot define new methods on non-local type reflect.Value|may not define methods on non-local type"
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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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