From f2eeeb83f23a6de883fb376f3bd75497feff659c Mon Sep 17 00:00:00 2001
From: Vincent Laporte <Vincent.Laporte@gmail.com>
Date: Mon, 6 Apr 2020 08:39:01 +0200
Subject: [PATCH] =?UTF-8?q?coqPackages.dpdgraph:=20fix=20build=20with=20OC?=
 =?UTF-8?q?aml=20=E2=89=A5=204.08?=
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---
 pkgs/development/coq-modules/dpdgraph/default.nix | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/pkgs/development/coq-modules/dpdgraph/default.nix b/pkgs/development/coq-modules/dpdgraph/default.nix
index 9e63e7766f0..689745003df 100644
--- a/pkgs/development/coq-modules/dpdgraph/default.nix
+++ b/pkgs/development/coq-modules/dpdgraph/default.nix
@@ -36,6 +36,8 @@ let params = {
 param = params.${coq.coq-version};
 in
 
+let hasWarning = stdenv.lib.versionAtLeast coq.ocamlPackages.ocaml.version "4.08"; in
+
 stdenv.mkDerivation {
   name = "coq${coq.coq-version}-dpdgraph-${param.version}";
   src = fetchFromGitHub {
@@ -49,6 +51,14 @@ stdenv.mkDerivation {
   buildInputs = [ coq ]
   ++ (with coq.ocamlPackages; [ ocaml camlp5 findlib ocamlgraph ]);
 
+  # dpd_compute.ml uses deprecated Pervasives.compare
+  # Versions prior to 0.6.5 do not have the WARN_ERR build flag
+  preConfigure = stdenv.lib.optionalString hasWarning ''
+    substituteInPlace Makefile.in --replace "-warn-error +a " ""
+  '';
+
+  buildFlags = stdenv.lib.optional hasWarning "WARN_ERR=";
+
   preInstall = ''
     mkdir -p $out/bin
   '';