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// 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.
// Test that implicit conversions of derived types to interface type
// in range loops work correctly.
package main
import (
"fmt"
"reflect"
)
func main() {
test{"int", "V"}.match(RangeArrayAny[V]())
test{"int", "V"}.match(RangeArrayIface[V]())
test{"V"}.match(RangeChanAny[V]())
test{"V"}.match(RangeChanIface[V]())
test{"K", "V"}.match(RangeMapAny[K, V]())
test{"K", "V"}.match(RangeMapIface[K, V]())
test{"int", "V"}.match(RangeSliceAny[V]())
test{"int", "V"}.match(RangeSliceIface[V]())
}
type test []string
func (t test) match(args ...any) {
if len(t) != len(args) {
fmt.Printf("FAIL: want %v values, have %v\n", len(t), len(args))
return
}
for i, want := range t {
if have := reflect.TypeOf(args[i]).Name(); want != have {
fmt.Printf("FAIL: %v: want type %v, have %v\n", i, want, have)
}
}
}
type iface interface{ M() int }
type K int
type V int
func (K) M() int { return 0 }
func (V) M() int { return 0 }
func RangeArrayAny[V any]() (k, v any) {
for k, v = range [...]V{zero[V]()} {
}
return
}
func RangeArrayIface[V iface]() (k any, v iface) {
for k, v = range [...]V{zero[V]()} {
}
return
}
func RangeChanAny[V any]() (v any) {
for v = range chanOf(zero[V]()) {
}
return
}
func RangeChanIface[V iface]() (v iface) {
for v = range chanOf(zero[V]()) {
}
return
}
func RangeMapAny[K comparable, V any]() (k, v any) {
for k, v = range map[K]V{zero[K](): zero[V]()} {
}
return
}
func RangeMapIface[K interface {
iface
comparable
}, V iface]() (k, v iface) {
for k, v = range map[K]V{zero[K](): zero[V]()} {
}
return
}
func RangeSliceAny[V any]() (k, v any) {
for k, v = range []V{zero[V]()} {
}
return
}
func RangeSliceIface[V iface]() (k any, v iface) {
for k, v = range []V{zero[V]()} {
}
return
}
func chanOf[T any](elems ...T) chan T {
c := make(chan T, len(elems))
for _, elem := range elems {
c <- elem
}
close(c)
return c
}
func zero[T any]() (_ T) { return }
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