mirror of
https://github.com/golang/go
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e24977d231
The next CL will remove the -G flag, effectively hard-coding it to its current default (-G=3). Change-Id: Ib4743b529206928f9f1cca9fdb19989728327831 Reviewed-on: https://go-review.googlesource.com/c/go/+/388534 Reviewed-by: Keith Randall <khr@golang.org> Trust: Matthew Dempsky <mdempsky@google.com> Run-TryBot: Matthew Dempsky <mdempsky@google.com> TryBot-Result: Gopher Robot <gobot@golang.org>
89 lines
1.6 KiB
Go
89 lines
1.6 KiB
Go
// run
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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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// Test method calls on type parameters
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package main
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import (
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"fmt"
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"reflect"
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"strconv"
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)
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// Simple constraint
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type Stringer interface {
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String() string
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}
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func stringify[T Stringer](s []T) (ret []string) {
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for _, v := range s {
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ret = append(ret, v.String())
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}
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return ret
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}
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type myint int
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func (i myint) String() string {
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return strconv.Itoa(int(i))
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}
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// Constraint with an embedded interface, but still only requires String()
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type Stringer2 interface {
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CanBeStringer2() int
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SubStringer2
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}
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type SubStringer2 interface {
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CanBeSubStringer2() int
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String() string
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}
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func stringify2[T Stringer2](s []T) (ret []string) {
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for _, v := range s {
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ret = append(ret, v.String())
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}
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return ret
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}
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func (myint) CanBeStringer2() int {
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return 0
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}
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func (myint) CanBeSubStringer2() int {
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return 0
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}
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// Test use of method values that are not called
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func stringify3[T Stringer](s []T) (ret []string) {
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for _, v := range s {
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f := v.String
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ret = append(ret, f())
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}
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return ret
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}
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func main() {
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x := []myint{myint(1), myint(2), myint(3)}
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got := stringify(x)
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want := []string{"1", "2", "3"}
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if !reflect.DeepEqual(got, want) {
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panic(fmt.Sprintf("got %s, want %s", got, want))
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}
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got = stringify2(x)
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if !reflect.DeepEqual(got, want) {
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panic(fmt.Sprintf("got %s, want %s", got, want))
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}
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got = stringify3(x)
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if !reflect.DeepEqual(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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