From ad6d08f863c6ea7a1f57b62f74fe8ed5dd9c69ea Mon Sep 17 00:00:00 2001
From: futhr <hi@futhr.io>
Date: Wed, 22 Apr 2026 02:15:45 +0200
Subject: [PATCH] Load using-module bytecode before @after_compile checks

Elixir 1.19's compiler no longer auto-loads the using module before
@after_compile fires, so function_exported?/2 reports false for the
freshly compiled struct and Brex.Operator (and any user struct rule)
fails to compile with "is not a struct".

Force-load the bytecode passed to the callback before running the
struct + evaluate/2 checks, and add Elixir 1.19 / OTP 28 to the CI
matrix so the regression is caught upstream.
---
 .github/workflows/ci.yml |  1 +
 lib/brex/rule/struct.ex  | 15 ++++++++++++++-
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 533c7b2..1bff905 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -12,6 +12,7 @@ jobs:
     with:
       matrix: |
         [
+          {"elixir": "1.19", "otp": "28.0", "alpine": "3.21"},
           {"elixir": "1.18", "otp": "27.0", "alpine": "3.20"},
           {"elixir": "1.17", "otp": "27.0", "alpine": "3.20"},
           {"elixir": "1.16", "otp": "26.2", "alpine": "3.20"}
diff --git a/lib/brex/rule/struct.ex b/lib/brex/rule/struct.ex
index ee3854c..700974c 100644
--- a/lib/brex/rule/struct.ex
+++ b/lib/brex/rule/struct.ex
@@ -28,7 +28,9 @@ defmodule Brex.Rule.Struct do
     end
   end
 
-  def __after_compile__(%{module: module} = env, _bytecode) do
+  def __after_compile__(%{module: module} = env, bytecode) do
+    ensure_loaded!(module, bytecode)
+
     is_struct_module(module) ||
       raise CompileError,
         file: env.file,
@@ -44,6 +46,17 @@ defmodule Brex.Rule.Struct do
           "cannot use #{inspect(__MODULE__)} on module #{inspect(module)} without defining evaluate/2"
   end
 
+  defp ensure_loaded!(module, bytecode) do
+    case Code.ensure_loaded(module) do
+      {:module, ^module} ->
+        :ok
+
+      {:error, _} ->
+        {:module, ^module} = :code.load_binary(module, ~c"nofile", bytecode)
+        :ok
+    end
+  end
+
   defp is_struct_module(module) do
     function_exported?(module, :__struct__, 0) and function_exported?(module, :__struct__, 1)
   end