Initial commit: Go 1.23 release state

test/closure2.go

@@ -0,0 +1,133 @@
+// run
+
+// Copyright 2015 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.
+
+// Check that these do not use "by value" capturing,
+// because changes are made to the value during the closure.
+
+package main
+
+var never bool
+
+func main() {
+	{
+		type X struct {
+			v int
+		}
+		var x X
+		func() {
+			x.v++
+		}()
+		if x.v != 1 {
+			panic("x.v != 1")
+		}
+
+		type Y struct {
+			X
+		}
+		var y Y
+		func() {
+			y.v = 1
+		}()
+		if y.v != 1 {
+			panic("y.v != 1")
+		}
+	}
+
+	{
+		type Z struct {
+			a [3]byte
+		}
+		var z Z
+		func() {
+			i := 0
+			for z.a[1] = 1; i < 10; i++ {
+			}
+		}()
+		if z.a[1] != 1 {
+			panic("z.a[1] != 1")
+		}
+	}
+
+	{
+		w := 0
+		tmp := 0
+		f := func() {
+			if w != 1 {
+				panic("w != 1")
+			}
+		}
+		func() {
+			tmp = w // force capture of w, but do not write to it yet
+			_ = tmp
+			func() {
+				func() {
+					w++ // write in a nested closure
+				}()
+			}()
+		}()
+		f()
+	}
+
+	{
+		var g func() int
+		var i int
+		for i = range [2]int{} {
+			if i == 0 {
+				g = func() int {
+					return i // test that we capture by ref here, i is mutated on every interaction
+				}
+			}
+		}
+		if g() != 1 {
+			panic("g() != 1")
+		}
+	}
+
+	{
+		var g func() int
+		q := 0
+		for range [2]int{} {
+			q++
+			g = func() int {
+				return q // test that we capture by ref here
+				// q++ must on a different decldepth than q declaration
+			}
+		}
+		if g() != 2 {
+			panic("g() != 2")
+		}
+	}
+
+	{
+		var g func() int
+		var a [2]int
+		q := 0
+		for a[func() int {
+			q++
+			return 0
+		}()] = range [2]int{} {
+			g = func() int {
+				return q // test that we capture by ref here
+				// q++ must on a different decldepth than q declaration
+			}
+		}
+		if g() != 2 {
+			panic("g() != 2")
+		}
+	}
+
+	{
+		var g func() int
+		q := 0
+		q, g = 1, func() int { return q }
+		if never {
+			g = func() int { return 2 }
+		}
+		if g() != 1 {
+			panic("g() != 1")
+		}
+	}
+}