From 98f36b2d744c02c844200cc0624ba5bc226660e5 Mon Sep 17 00:00:00 2001
From: Vincent Laporte <Vincent.Laporte@gmail.com>
Date: Wed, 1 Feb 2023 09:20:48 +0100
Subject: [PATCH] ocamlPackages.dune_3: enable for OCaml < 4.08

---
 pkgs/development/ocaml-modules/chrome-trace/default.nix | 1 +
 pkgs/development/ocaml-modules/ordering/default.nix     | 1 +
 pkgs/development/ocaml-modules/xdg/default.nix          | 1 +
 pkgs/development/tools/ocaml/js_of_ocaml/compiler.nix   | 1 +
 pkgs/top-level/ocaml-packages.nix                       | 7 ++++++-
 5 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/pkgs/development/ocaml-modules/chrome-trace/default.nix b/pkgs/development/ocaml-modules/chrome-trace/default.nix
index fb6c14b3362..9c427d34375 100644
--- a/pkgs/development/ocaml-modules/chrome-trace/default.nix
+++ b/pkgs/development/ocaml-modules/chrome-trace/default.nix
@@ -4,6 +4,7 @@ buildDunePackage rec {
   pname = "chrome-trace";
   inherit (dune_3) src version;
 
+  minimalOCamlVersion = "4.08";
   duneVersion = "3";
 
   dontAddPrefix = true;
diff --git a/pkgs/development/ocaml-modules/ordering/default.nix b/pkgs/development/ocaml-modules/ordering/default.nix
index c3bffc013f9..8613ccf9ae0 100644
--- a/pkgs/development/ocaml-modules/ordering/default.nix
+++ b/pkgs/development/ocaml-modules/ordering/default.nix
@@ -4,6 +4,7 @@ buildDunePackage {
   pname = "ordering";
   inherit (dune_3) version src;
   duneVersion = "3";
+  minimalOCamlVersion = "4.08";
 
   dontAddPrefix = true;
 
diff --git a/pkgs/development/ocaml-modules/xdg/default.nix b/pkgs/development/ocaml-modules/xdg/default.nix
index 8d3810fa7e9..52543175e07 100644
--- a/pkgs/development/ocaml-modules/xdg/default.nix
+++ b/pkgs/development/ocaml-modules/xdg/default.nix
@@ -5,6 +5,7 @@ buildDunePackage rec {
   inherit (dune_3) src version;
 
   duneVersion = "3";
+  minimalOCamlVersion = "4.08";
 
   dontAddPrefix = true;
 
diff --git a/pkgs/development/tools/ocaml/js_of_ocaml/compiler.nix b/pkgs/development/tools/ocaml/js_of_ocaml/compiler.nix
index cec91a02f20..8533c1ac41c 100644
--- a/pkgs/development/tools/ocaml/js_of_ocaml/compiler.nix
+++ b/pkgs/development/tools/ocaml/js_of_ocaml/compiler.nix
@@ -7,6 +7,7 @@ buildDunePackage rec {
   pname = "js_of_ocaml-compiler";
   version = "4.1.0";
   duneVersion = "3";
+  minimalOCamlVersion = "4.08";
 
   src = fetchurl {
     url = "https://github.com/ocsigen/js_of_ocaml/releases/download/${version}/js_of_ocaml-${version}.tbz";
diff --git a/pkgs/top-level/ocaml-packages.nix b/pkgs/top-level/ocaml-packages.nix
index 301495961e3..57759ae28ee 100644
--- a/pkgs/top-level/ocaml-packages.nix
+++ b/pkgs/top-level/ocaml-packages.nix
@@ -357,7 +357,12 @@ let
       then pkgs.dune_2
       else throw "dune_2 is not available for OCaml ${ocaml.version}";
 
-    dune_3 = callPackage ../development/tools/ocaml/dune/3.nix { };
+    dune_3 =
+      if lib.versionAtLeast ocaml.version "4.08"
+      then callPackage ../development/tools/ocaml/dune/3.nix { }
+      else if lib.versionAtLeast ocaml.version "4.02"
+      then pkgs.dune_3
+      else throw "dune_3 is not available for OCaml ${ocaml.version}";
 
     dune-action-plugin = callPackage ../development/ocaml-modules/dune-action-plugin { };