add test

tests/issues/test_issue_2615.odin

@@ -0,0 +1,19 @@
+// Tests issue https://github.com/odin-lang/Odin/issues/2615
+// Cannot iterate over string literals
+package test_issues
+
+import "core:testing"
+
+@(test)
+test_cannot_iterate_over_string_literal :: proc(t: ^testing.T) {
+	for c, i in "fo世" {
+		switch i {
+		case 0:
+			testing.expect_value(t, c, 'f')
+		case 1:
+			testing.expect_value(t, c, 'o')
+		case 2:
+			testing.expect_value(t, c, '世')
+		}
+	}
+}