[release-branch.go1.20] cmd/compile: fix ir.StaticValue for ORANGE

Range statement will mutate the key and value, so we should treat them as reassigned.

Fixes #59580

Change-Id: I9c6b67d938760a0c6a1d9739f2737c67af4a3a10
Reviewed-on: https://go-review.googlesource.com/c/go/+/483855
Run-TryBot: Wayne Zuo <wdvxdr@golangcn.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Auto-Submit: Keith Randall <khr@golang.org>
Reviewed-by: Keith Randall <khr@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
(cherry picked from commit 89567a35c1)
Reviewed-on: https://go-review.googlesource.com/c/go/+/484136
Run-TryBot: Matthew Dempsky <mdempsky@google.com>

src/cmd/compile/internal/ir/expr.go

@@ -959,6 +959,11 @@ func reassigned(name *Name) bool {
 			if isName(OuterValue(n.X)) {
 				return true
 			}
+		case ORANGE:
+			n := n.(*RangeStmt)
+			if isName(n.Key) || isName(n.Value) {
+				return true
+			}
 		case OCLOSURE:
 			n := n.(*ClosureExpr)
 			if Any(n.Func, do) {

test/fixedbugs/issue59572.go

@@ -0,0 +1,30 @@
+// run
+
+// 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.
+
+package main
+
+func foo() {
+	println("foo")
+}
+
+func main() {
+	fn := foo
+	for _, fn = range list {
+		fn()
+	}
+}
+
+var list = []func(){
+	func() {
+		println("1")
+	},
+	func() {
+		println("2")
+	},
+	func() {
+		println("3")
+	},
+}

test/fixedbugs/issue59572.out

@@ -0,0 +1,3 @@
+1
+2
+3