go/types, types2: add test case for missing return

The respective issue was fixed in types2 with CL 356189;
and the problem didn't exist in go/types. This CL simply
adds the test case to the type checkers as well.

For #49003.

Change-Id: Ib50ee8bb0ad21f2916f2b79d4f77593302899a3e
Reviewed-on: https://go-review.googlesource.com/c/go/+/356411
Trust: Robert Griesemer <gri@golang.org>
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue49003.go b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue49003.go
new file mode 100644
index 0000000..ece1a27
--- /dev/null
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue49003.go
@@ -0,0 +1,10 @@
+// Copyright 2021 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 p
+
+func f(s string) int {
+	for range s {
+	}
+} // ERROR missing return
diff --git a/src/go/types/testdata/fixedbugs/issue49003.go b/src/go/types/testdata/fixedbugs/issue49003.go
new file mode 100644
index 0000000..ece1a27
--- /dev/null
+++ b/src/go/types/testdata/fixedbugs/issue49003.go
@@ -0,0 +1,10 @@
+// Copyright 2021 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 p
+
+func f(s string) int {
+	for range s {
+	}
+} // ERROR missing return