From 2ac95e911633fd5059e72e2b36737562da12723d Mon Sep 17 00:00:00 2001
From: sabiwara <sabiwara@proton.me>
Date: Sat, 20 Sep 2025 10:15:01 +0900
Subject: [PATCH 1/3] Assert scope is not match/guard when using escaped
 regexes

---
 lib/elixir/lib/kernel.ex              |  6 ++++++
 lib/elixir/lib/regex.ex               |  1 +
 lib/elixir/test/elixir/macro_test.exs | 10 ++++++++--
 lib/elixir/test/elixir/regex_test.exs | 19 +++++++++++++++++++
 4 files changed, 34 insertions(+), 2 deletions(-)

diff --git a/lib/elixir/lib/kernel.ex b/lib/elixir/lib/kernel.ex
index c2476ea290a..f8c6e7068c4 100644
--- a/lib/elixir/lib/kernel.ex
+++ b/lib/elixir/lib/kernel.ex
@@ -7004,6 +7004,12 @@ defmodule Kernel do
 
   ## Shared functions
 
+  @doc false
+  defmacro __assert_assert_no_match_or_guard_scope__(exp) do
+    assert_no_match_or_guard_scope(__CALLER__.context, exp)
+    nil
+  end
+
   defp assert_module_scope(env, fun, arity) do
     case env.module do
       nil -> raise ArgumentError, "cannot invoke #{fun}/#{arity} outside module"
diff --git a/lib/elixir/lib/regex.ex b/lib/elixir/lib/regex.ex
index d07f4479c25..47cf316b7f7 100644
--- a/lib/elixir/lib/regex.ex
+++ b/lib/elixir/lib/regex.ex
@@ -1018,6 +1018,7 @@ defmodule Regex do
           {:ok, exported} = :re.compile(regex.source, [:export] ++ regex.opts)
 
           quote do
+            __assert_assert_no_match_or_guard_scope__("an escaped Regex")
             :re.import(unquote(Macro.escape(exported)))
           end
 
diff --git a/lib/elixir/test/elixir/macro_test.exs b/lib/elixir/test/elixir/macro_test.exs
index ba9889d6b2c..a2d1a817fa3 100644
--- a/lib/elixir/test/elixir/macro_test.exs
+++ b/lib/elixir/test/elixir/macro_test.exs
@@ -167,8 +167,14 @@ defmodule MacroTest do
                [],
                [
                  __struct__: Regex,
-                 re_pattern:
-                   {{:., [], [:re, :import]}, [], [{:{}, [], [:re_exported_pattern | _]}]},
+                 re_pattern: {
+                   :__block__,
+                   [],
+                   [
+                     {:__assert_assert_no_match_or_guard_scope__, _, _},
+                     {{:., [], [:re, :import]}, [], [{:{}, [], [:re_exported_pattern | _]}]}
+                   ]
+                 },
                  source: "foo",
                  opts: []
                ]
diff --git a/lib/elixir/test/elixir/regex_test.exs b/lib/elixir/test/elixir/regex_test.exs
index 166a3281360..7ab7e1c79c3 100644
--- a/lib/elixir/test/elixir/regex_test.exs
+++ b/lib/elixir/test/elixir/regex_test.exs
@@ -28,6 +28,25 @@ defmodule RegexTest do
     end
   end
 
+  @tag :re_import
+  test "module attribute in match context" do
+    assert_raise(
+      ArgumentError,
+      ~r/invalid expression in match, an escaped Regex is not allowed in patterns such as function clauses/,
+      fn ->
+        Code.eval_quoted(
+          quote do
+            defmodule ModAttrGuard do
+              @regex ~r/example/
+              def example?(@regex), do: true
+              def example?(_), do: false
+            end
+          end
+        )
+      end
+    )
+  end
+
   test "multiline" do
     refute Regex.match?(~r/^b$/, "a\nb\nc")
     assert Regex.match?(~r/^b$/m, "a\nb\nc")

From c1dee89adb5cd1126eb301ded559aa3e130d6280 Mon Sep 17 00:00:00 2001
From: sabiwara <sabiwara@proton.me>
Date: Sat, 20 Sep 2025 17:27:52 +0900
Subject: [PATCH 2/3] Use Regex.__compile_pattern__ macro instead

---
 lib/elixir/lib/kernel.ex |  6 ------
 lib/elixir/lib/regex.ex  | 15 +++++++++++++--
 2 files changed, 13 insertions(+), 8 deletions(-)

diff --git a/lib/elixir/lib/kernel.ex b/lib/elixir/lib/kernel.ex
index f8c6e7068c4..c2476ea290a 100644
--- a/lib/elixir/lib/kernel.ex
+++ b/lib/elixir/lib/kernel.ex
@@ -7004,12 +7004,6 @@ defmodule Kernel do
 
   ## Shared functions
 
-  @doc false
-  defmacro __assert_assert_no_match_or_guard_scope__(exp) do
-    assert_no_match_or_guard_scope(__CALLER__.context, exp)
-    nil
-  end
-
   defp assert_module_scope(env, fun, arity) do
     case env.module do
       nil -> raise ArgumentError, "cannot invoke #{fun}/#{arity} outside module"
diff --git a/lib/elixir/lib/regex.ex b/lib/elixir/lib/regex.ex
index 47cf316b7f7..c0b2451a043 100644
--- a/lib/elixir/lib/regex.ex
+++ b/lib/elixir/lib/regex.ex
@@ -1018,8 +1018,8 @@ defmodule Regex do
           {:ok, exported} = :re.compile(regex.source, [:export] ++ regex.opts)
 
           quote do
-            __assert_assert_no_match_or_guard_scope__("an escaped Regex")
-            :re.import(unquote(Macro.escape(exported)))
+            require Regex
+            Regex.__import_pattern__(unquote(Macro.escape(exported)))
           end
 
         # TODO: Remove this when we require Erlang/OTP 28.1+
@@ -1042,4 +1042,15 @@ defmodule Regex do
       }
     end
   end
+
+  @doc false
+  defmacro __import_pattern__(pattern) do
+    if __CALLER__.context in [:match, :guard] do
+      raise ArgumentError, "escaped"
+    end
+
+    quote do
+      :re.import(unquote(pattern))
+    end
+  end
 end

From 4012cd0256386ab62946e92866f434f58bf61758 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jos=C3=A9=20Valim?= <jose.valim@gmail.com>
Date: Thu, 25 Sep 2025 12:54:49 +0200
Subject: [PATCH 3/3] Add nil check for regex pattern in pattern AST

---
 lib/elixir/lib/regex.ex | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/lib/elixir/lib/regex.ex b/lib/elixir/lib/regex.ex
index c0b2451a043..3cf41bd8d99 100644
--- a/lib/elixir/lib/regex.ex
+++ b/lib/elixir/lib/regex.ex
@@ -1008,6 +1008,9 @@ defmodule Regex do
 
     pattern_ast =
       cond do
+        is_nil(regex.re_pattern) ->
+          nil
+
         # TODO: Remove this when we require Erlang/OTP 28+
         # Before OTP 28.0, patterns did not contain any refs and could be safely be escaped
         :erlang.system_info(:otp_release) < [?2, ?8] ->