From 1e55f8db32136bc8c286245bf5aeecacc8d1e741 Mon Sep 17 00:00:00 2001
From: Vincent Laporte <Vincent.Laporte@gmail.com>
Date: Mon, 6 Oct 2025 22:12:34 +0200
Subject: [PATCH] ocamlPackages.xtmpl_ppx: fix for OCaml 5.4

---
 pkgs/development/ocaml-modules/xtmpl/ppx.nix | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/pkgs/development/ocaml-modules/xtmpl/ppx.nix b/pkgs/development/ocaml-modules/xtmpl/ppx.nix
index 3206c31bac17..749a83bb6201 100644
--- a/pkgs/development/ocaml-modules/xtmpl/ppx.nix
+++ b/pkgs/development/ocaml-modules/xtmpl/ppx.nix
@@ -9,6 +9,12 @@ buildDunePackage {
 
   inherit (xtmpl) src version;
 
+  # Fix for ppxlib ≥ 0.37
+  postPatch = ''
+    substituteInPlace ppx/ppx_xtmpl.ml --replace-fail 'Parse.longident b' \
+      'Astlib.Longident.parse s'
+  '';
+
   buildInputs = [
     ppxlib
     xtmpl