mirror of
https://github.com/golang/go
synced 2024-11-17 20:44:47 -07:00
64b6e44ad7
When we convert a type to a shaped interface type, we are not able to recognize the itab. So passing the itab by dictionary as the workaround. Fixes #52026. Change-Id: I75c23c7dd215daf9761dc24116a8af2c28c6d948 Reviewed-on: https://go-review.googlesource.com/c/go/+/401034 Run-TryBot: Wayne Zuo <wdvxdr@golangcn.org> TryBot-Result: Gopher Robot <gobot@golang.org> Auto-Submit: Keith Randall <khr@golang.org> Reviewed-by: Keith Randall <khr@google.com> Reviewed-by: David Chase <drchase@google.com> Reviewed-by: Keith Randall <khr@golang.org>
51 lines
735 B
Go
51 lines
735 B
Go
// run
|
|
|
|
// Copyright 2022 The Go Authors. All rights reserved.
|
|
// Use of this source code is governed by a BSD-style
|
|
// license that can be found in the LICENSE file.
|
|
|
|
package main
|
|
|
|
func returnOption[T any](n int) Option[T] {
|
|
if n == 1 {
|
|
return Some[T]{}
|
|
} else {
|
|
return None{}
|
|
}
|
|
}
|
|
|
|
type Option[T any] interface {
|
|
sealedOption()
|
|
}
|
|
|
|
type Some[T any] struct {
|
|
val T
|
|
}
|
|
|
|
func (s Some[T]) Value() T {
|
|
return s.val
|
|
}
|
|
|
|
func (s Some[T]) sealedOption() {}
|
|
|
|
type None struct{}
|
|
|
|
func (s None) sealedOption() {}
|
|
|
|
func main() {
|
|
s := returnOption[int](1)
|
|
_ = s.(Some[int])
|
|
|
|
s = returnOption[int](0)
|
|
_ = s.(None)
|
|
|
|
switch (any)(s).(type) {
|
|
case Some[int]:
|
|
panic("s is a Some[int]")
|
|
case None:
|
|
// ok
|
|
default:
|
|
panic("oops")
|
|
}
|
|
}
|