--- /dev/null
+// run -goexperiment range
+
+// Copyright 2023 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 the 'for range' construct ranging over functions.
+
+package main
+
+var gj int
+
+func yield4x(yield func() bool) {
+ _ = yield() && yield() && yield() && yield()
+}
+
+func yield4(yield func(int) bool) {
+ _ = yield(1) && yield(2) && yield(3) && yield(4)
+}
+
+func yield3(yield func(int) bool) {
+ _ = yield(1) && yield(2) && yield(3)
+}
+
+func yield2(yield func(int) bool) {
+ _ = yield(1) && yield(2)
+}
+
+func testfunc0() {
+ j := 0
+ for range yield4x {
+ j++
+ }
+ if j != 4 {
+ println("wrong count ranging over yield4x:", j)
+ panic("testfunc0")
+ }
+
+ j = 0
+ for _ = range yield4 {
+ j++
+ }
+ if j != 4 {
+ println("wrong count ranging over yield4:", j)
+ panic("testfunc0")
+ }
+}
+
+func testfunc1() {
+ bad := false
+ j := 1
+ for i := range yield4 {
+ if i != j {
+ println("range var", i, "want", j)
+ bad = true
+ }
+ j++
+ }
+ if j != 5 {
+ println("wrong count ranging over f:", j)
+ bad = true
+ }
+ if bad {
+ panic("testfunc1")
+ }
+}
+
+func testfunc2() {
+ bad := false
+ j := 1
+ var i int
+ for i = range yield4 {
+ if i != j {
+ println("range var", i, "want", j)
+ bad = true
+ }
+ j++
+ }
+ if j != 5 {
+ println("wrong count ranging over f:", j)
+ bad = true
+ }
+ if i != 4 {
+ println("wrong final i ranging over f:", i)
+ bad = true
+ }
+ if bad {
+ panic("testfunc2")
+ }
+}
+
+func testfunc3() {
+ bad := false
+ j := 1
+ var i int
+ for i = range yield4 {
+ if i != j {
+ println("range var", i, "want", j)
+ bad = true
+ }
+ j++
+ if i == 2 {
+ break
+ }
+ continue
+ }
+ if j != 3 {
+ println("wrong count ranging over f:", j)
+ bad = true
+ }
+ if i != 2 {
+ println("wrong final i ranging over f:", i)
+ bad = true
+ }
+ if bad {
+ panic("testfunc3")
+ }
+}
+
+func testfunc4() {
+ bad := false
+ j := 1
+ var i int
+ func() {
+ for i = range yield4 {
+ if i != j {
+ println("range var", i, "want", j)
+ bad = true
+ }
+ j++
+ if i == 2 {
+ return
+ }
+ }
+ }()
+ if j != 3 {
+ println("wrong count ranging over f:", j)
+ bad = true
+ }
+ if i != 2 {
+ println("wrong final i ranging over f:", i)
+ bad = true
+ }
+ if bad {
+ panic("testfunc3")
+ }
+}
+
+func func5() (int, int) {
+ for i := range yield4 {
+ return 10, i
+ }
+ panic("still here")
+}
+
+func testfunc5() {
+ x, y := func5()
+ if x != 10 || y != 1 {
+ println("wrong results", x, y, "want", 10, 1)
+ panic("testfunc5")
+ }
+}
+
+func func6() (z, w int) {
+ for i := range yield4 {
+ z = 10
+ w = i
+ return
+ }
+ panic("still here")
+}
+
+func testfunc6() {
+ x, y := func6()
+ if x != 10 || y != 1 {
+ println("wrong results", x, y, "want", 10, 1)
+ panic("testfunc6")
+ }
+}
+
+var saved []int
+
+func save(x int) {
+ saved = append(saved, x)
+}
+
+func printslice(s []int) {
+ print("[")
+ for i, x := range s {
+ if i > 0 {
+ print(", ")
+ }
+ print(x)
+ }
+ print("]")
+}
+
+func eqslice(s, t []int) bool {
+ if len(s) != len(t) {
+ return false
+ }
+ for i, x := range s {
+ if x != t[i] {
+ return false
+ }
+ }
+ return true
+}
+
+func func7() {
+ defer save(-1)
+ for i := range yield4 {
+ defer save(i)
+ }
+ defer save(5)
+}
+
+func checkslice(name string, saved, want []int) {
+ if !eqslice(saved, want) {
+ print("wrong results ")
+ printslice(saved)
+ print(" want ")
+ printslice(want)
+ print("\n")
+ panic(name)
+ }
+}
+
+func testfunc7() {
+ saved = nil
+ func7()
+ want := []int{5, 4, 3, 2, 1, -1}
+ checkslice("testfunc7", saved, want)
+}
+
+func func8() {
+ defer save(-1)
+ for i := range yield2 {
+ for j := range yield3 {
+ defer save(i*10 + j)
+ }
+ defer save(i)
+ }
+ defer save(-2)
+ for i := range yield4 {
+ defer save(i)
+ }
+ defer save(-3)
+}
+
+func testfunc8() {
+ saved = nil
+ func8()
+ want := []int{-3, 4, 3, 2, 1, -2, 2, 23, 22, 21, 1, 13, 12, 11, -1}
+ checkslice("testfunc8", saved, want)
+}
+
+func func9() {
+ n := 0
+ for _ = range yield2 {
+ for _ = range yield3 {
+ n++
+ defer save(n)
+ }
+ }
+}
+
+func testfunc9() {
+ saved = nil
+ func9()
+ want := []int{6, 5, 4, 3, 2, 1}
+ checkslice("testfunc9", saved, want)
+}
+
+// test that range evaluates the index and value expressions
+// exactly once per iteration.
+
+var ncalls = 0
+
+func getvar(p *int) *int {
+ ncalls++
+ return p
+}
+
+func iter2(list ...int) func(func(int, int) bool) {
+ return func(yield func(int, int) bool) {
+ for i, x := range list {
+ if !yield(i, x) {
+ return
+ }
+ }
+ }
+}
+
+func testcalls() {
+ var i, v int
+ ncalls = 0
+ si := 0
+ sv := 0
+ for *getvar(&i), *getvar(&v) = range iter2(1, 2) {
+ si += i
+ sv += v
+ }
+ if ncalls != 4 {
+ println("wrong number of calls:", ncalls, "!= 4")
+ panic("fail")
+ }
+ if si != 1 || sv != 3 {
+ println("wrong sum in testcalls", si, sv)
+ panic("fail")
+ }
+}
+
+func main() {
+ testfunc0()
+ testfunc1()
+ testfunc2()
+ testfunc3()
+ testfunc4()
+ testfunc5()
+ testfunc6()
+ testfunc7()
+ testfunc8()
+ testfunc9()
+ testcalls()
+}