From 9b419c67cfeb210d333fc0c34ae6e8c7a987d443 Mon Sep 17 00:00:00 2001
From: Weijia Wang <9713184+wegank@users.noreply.github.com>
Date: Tue, 18 Apr 2023 14:18:31 +0300
Subject: [PATCH] ocaml-ng.ocamlPackages_4_02.bdd: fix build

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

diff --git a/pkgs/development/ocaml-modules/bdd/default.nix b/pkgs/development/ocaml-modules/bdd/default.nix
index 1ddb8634f3c..358d92d3505 100644
--- a/pkgs/development/ocaml-modules/bdd/default.nix
+++ b/pkgs/development/ocaml-modules/bdd/default.nix
@@ -17,6 +17,12 @@ buildDunePackage {
     hash = "sha256-3mJZlAFQsI7AgrNQOe6N94CDfX5gXYqQBooV0jcoYEA=";
   };
 
+  # Fix build with OCaml 4.02
+  postPatch = ''
+    substituteInPlace lib/bdd.ml \
+      --replace "Buffer.truncate Format.stdbuf 0;" "Buffer.clear Format.stdbuf;"
+  '';
+
   propagatedBuildInputs = [
     stdlib-shims
   ];