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a91d0b649c
We may revisit this decision in a future release. By disallowing this for Go 1.18 we are ensuring that we don't lock in the generics design in a place that may need to change later. (Type declarations are the primary construct where it crucially matters what the underlying type of a type parameter is.) Comment out all tests that rely on this feature; add comments referring to issue so we can find all places easily should we change our minds. Fixes #45639. Change-Id: I730510e4da66d3716d455a9071c7778a1e4a1152 Reviewed-on: https://go-review.googlesource.com/c/go/+/359177 Trust: Robert Griesemer <gri@golang.org> Trust: Dan Scales <danscales@google.com> Reviewed-by: Dan Scales <danscales@google.com>
38 lines
948 B
Go
38 lines
948 B
Go
// run -gcflags=-G=3
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// Copyright 2021 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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package main
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type FooType[T any] interface {
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Foo(BarType[T]) string
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}
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type BarType[T any] interface {
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Bar(FooType[T]) string
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}
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// For now, a lone type parameter is not permitted as RHS in a type declaration (issue #45639).
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// type Baz[T any] T
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// func (l Baz[T]) Foo(v BarType[T]) string {
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// return v.Bar(l)
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// }
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// type Bob[T any] T
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// func (l Bob[T]) Bar(v FooType[T]) string {
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// if v,ok := v.(Baz[T]);ok{
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// return fmt.Sprintf("%v%v",v,l)
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// }
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// return ""
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// }
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func main() {
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// For now, a lone type parameter is not permitted as RHS in a type declaration (issue #45639).
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// var baz Baz[int] = 123
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// var bob Bob[int] = 456
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//
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// if got, want := baz.Foo(bob), "123456"; got != want {
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// panic(fmt.Sprintf("got %s want %s", got, want))
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// }
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}
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