Add warning on OTP28.0

Author: sabiwara

lib/elixir/lib/regex.ex

@@ -1025,6 +1025,17 @@ defmodule Regex do
         # OTP 28.0 works in degraded mode performance-wise, we need to recompile from the source
         true ->
           quote do
+            IO.warn_once(
+              {Regex, :__escape__},
+              fn ->
+                """
+                Regexes will be re-compiled from source at runtime, which will cause degraded performance.
+                This can be fixed by using Erlang OTP 28.1+ or 27-.
+                """
+              end,
+              3
+            )
+
             {:ok, pattern} =
               :re.compile(unquote(Macro.escape(regex.source)), unquote(Macro.escape(regex.opts)))