reflect: add test that method values have the same code pointers

Updates #40592

Change-Id: I16252dd57aceb5c49ddc11d8c12c601ca87ca902
Reviewed-on: https://go-review.googlesource.com/c/go/+/356252
Trust: Cuong Manh Le <[email protected]>
Run-TryBot: Cuong Manh Le <[email protected]>
TryBot-Result: Go Bot <[email protected]>
Reviewed-by: Keith Randall <[email protected]>

Author: cuonglm

src/reflect/all_test.go

@@ -2511,6 +2511,11 @@ func TestMethodValue(t *testing.T) {
 	p := Point{3, 4}
 	var i int64
 
+	// Check that method value have the same underlying code pointers.
+	if p1, p2 := ValueOf(Point{1, 1}).Method(1), ValueOf(Point{2, 2}).Method(1); p1.Pointer() != p2.Pointer() {
+		t.Errorf("methodValueCall mismatched: %v - %v", p1, p2)
+	}
+
 	// Curried method of value.
 	tfunc := TypeOf((func(int) int)(nil))
 	v := ValueOf(p).Method(1)