From baba13293398e73d4fa3cb90c627f8aca7086a6b Mon Sep 17 00:00:00 2001
From: "Randall C. O'Reilly" <oreilly@ucdavis.edu>
Date: Fri, 19 Jul 2024 12:19:46 -0700
Subject: [PATCH] fix case where loopvar is redefined with an explicit i := i
 define (pre 1.22 fix for loopvar) with the same name as the original.  all
 the other tests were using a new variable name, so we missed this case.

---
 _test/closure19.go | 18 ++++++++++++++++++
 _test/closure20.go | 18 ++++++++++++++++++
 interp/cfg.go      | 16 ++++++++++++++++
 3 files changed, 52 insertions(+)
 create mode 100644 _test/closure19.go
 create mode 100644 _test/closure20.go

diff --git a/_test/closure19.go b/_test/closure19.go
new file mode 100644
index 00000000..7ad87fb5
--- /dev/null
+++ b/_test/closure19.go
@@ -0,0 +1,18 @@
+package main
+
+func main() {
+	foos := []func(){}
+
+	for i := 0; i < 3; i++ {
+		i := i
+		foos = append(foos, func() { println(i) })
+	}
+	foos[0]()
+	foos[1]()
+	foos[2]()
+}
+
+// Output:
+// 0
+// 1
+// 2
diff --git a/_test/closure20.go b/_test/closure20.go
new file mode 100644
index 00000000..7afb6708
--- /dev/null
+++ b/_test/closure20.go
@@ -0,0 +1,18 @@
+package main
+
+func main() {
+	foos := []func(){}
+
+	for i := range 3 {
+		i := i
+		foos = append(foos, func() { println(i) })
+	}
+	foos[0]()
+	foos[1]()
+	foos[2]()
+}
+
+// Output:
+// 0
+// 1
+// 2
diff --git a/interp/cfg.go b/interp/cfg.go
index 227a73a2..933e2a93 100644
--- a/interp/cfg.go
+++ b/interp/cfg.go
@@ -734,6 +734,22 @@ func (interp *Interpreter) cfg(root *node, sc *scope, importPath, pkgName string
 						return
 					}
 					if sc.global || sc.isRedeclared(dest) {
+						if n.anc != nil && n.anc.anc != nil && (n.anc.anc.kind == forStmt7 || n.anc.anc.kind == rangeStmt) {
+							// check for redefine of for loop variables, which are now auto-defined in go1.22
+							init := n.anc.anc.child[0]
+							var fi *node // for ident
+							if n.anc.anc.kind == forStmt7 {
+								if init.kind == defineStmt && len(init.child) >= 2 && init.child[0].kind == identExpr {
+									fi = init.child[0]
+								}
+							} else { // range
+								fi = init
+							}
+							if fi != nil && dest.ident == fi.ident {
+								n.gen = nop
+								break
+							}
+						}
 						// Do not overload existing symbols (defined in GTA) in global scope.
 						sym, _, _ = sc.lookup(dest.ident)
 					}