From 05758917329879da4b814e4786a9763d0c299432 Mon Sep 17 00:00:00 2001
From: woylie <13847569+woylie@users.noreply.github.com>
Date: Sun, 9 Aug 2026 16:53:29 +0200
Subject: [PATCH] avoid compile-time dependency on modules named in derive

---
 lib/ecto/schema.ex | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/lib/ecto/schema.ex b/lib/ecto/schema.ex
index 7e52f245c5..f91a86c217 100644
--- a/lib/ecto/schema.ex
+++ b/lib/ecto/schema.ex
@@ -2390,10 +2390,12 @@ defmodule Ecto.Schema do
     on_writable_violation_default = Module.get_attribute(module, :on_writable_violation, :nothing)
 
     struct_fields = Module.get_attribute(module, :ecto_struct_fields) |> Enum.reverse()
-    derive = Module.get_attribute(module, :derive)
 
-    if redacted_fields != [] and not List.keymember?(derive, Inspect, 0) and
-         derive_inspect?(module) do
+    # Reading @derive makes every module named in its options a compile-time
+    # dependency of the schema. Keep the read last so it is skipped unless a
+    # redacted field actually requires deriving Inspect.
+    if redacted_fields != [] and derive_inspect?(module) and
+         not List.keymember?(Module.get_attribute(module, :derive), Inspect, 0) do
       Module.put_attribute(module, :derive, {Inspect, except: redacted_fields})
     end