Use new OTP28.1 :re.import in escaped regex AST

erlang/otp#9976

Author: sabiwara

lib/elixir/lib/kernel.ex

@@ -6647,16 +6647,26 @@ defmodule Kernel do
   end
 
   defp compile_regex(binary_or_tuple, options) do
-    # TODO: Remove this when we require Erlang/OTP 28+
-    case is_binary(binary_or_tuple) and :erlang.system_info(:otp_release) < [?2, ?8] do
+    bin_opts = :binary.list_to_bin(options)
+
+    # TODO: Remove this when we require Erlang/OTP 28.1+
+    case is_binary(binary_or_tuple) and compile_time_regexes_supported?() do
       true ->
-        Macro.escape(Regex.compile!(binary_or_tuple, :binary.list_to_bin(options)))
+        Macro.escape(Regex.compile!(binary_or_tuple, bin_opts))
 
       false ->
-        quote(do: Regex.compile!(unquote(binary_or_tuple), unquote(:binary.list_to_bin(options))))
+        quote(do: Regex.compile!(unquote(binary_or_tuple), unquote(bin_opts)))
     end
   end
 
+  defp compile_time_regexes_supported? do
+    # OTP 28.0 introduced refs in patterns, which can't be used in AST anymore
+    # OTP 28.1 introduced :re.import/1 which allows us to fix this in Macro.escape
+    :erlang.system_info(:otp_release) < [?2, ?8] or
+      (Code.ensure_loaded?(:re) and
+         function_exported?(:re, :import, 1))
+  end
+
   @doc ~S"""
   Handles the sigil `~D` for dates.
 

lib/elixir/src/elixir_quote.erl

@@ -168,6 +168,21 @@ do_escape(BitString, _) when is_bitstring(BitString) ->
       {'<<>>', [], [{'::', [], [Bits, {size, [], [Size]}]}, {'::', [], [Bytes, {binary, [], nil}]}]}
   end;
 
+do_escape(#{
+  '__struct__' := 'Elixir.Regex',
+  're_pattern' := {re_pattern, _, _, _, Ref},
+  'source' := Source,
+  'opts' := Opts
+}, Q) when is_reference(Ref), is_binary(Source), is_list(Opts)  ->
+  {ok, ExportedPattern} = re:compile(Source, [export | Opts]),
+  PatternAst = {{'.', [], ['re', 'import']}, [], [do_escape(ExportedPattern, Q)]},
+  {'%{}', [], [
+    {'__struct__', 'Elixir.Regex'},
+    {'re_pattern', PatternAst},
+    {'source', Source},
+    {'opts', do_escape(Opts, Q)}
+  ]};
+
 do_escape(Map, Q) when is_map(Map) ->
   TT = [escape_map_key_value(K, V, Map, Q) || {K, V} <- lists:sort(maps:to_list(Map))],
   {'%{}', [], TT};