ocamlPackages.lwt_ppx: use independent source from lwt

1 files changed, 14 insertions, 2 deletions

diff --git a/pkgs/development/ocaml-modules/lwt/ppx.nix b/pkgs/development/ocaml-modules/lwt/ppx.nix
index 4ad6fc2c471..3cf4541aa01 100644
--- a/pkgs/development/ocaml-modules/lwt/ppx.nix
+++ b/pkgs/development/ocaml-modules/lwt/ppx.nix
@@ -1,9 +1,21 @@
-{ buildDunePackage, lwt, ppx_tools_versioned }:
+{ fetchzip, buildDunePackage, lwt, ppx_tools_versioned }:
 
 buildDunePackage {
   pname = "lwt_ppx";
+  version = "1.2.4";
+
+  src = fetchzip {
+    # `lwt_ppx` has a different release cycle than Lwt, but it's included in
+    # one of its release bundles.
+    # Because there could exist an Lwt release _without_ a `lwt_ppx` release,
+    # this `src` field doesn't inherit from the Lwt derivation.
+    #
+    # This is particularly useful for overriding Lwt without breaking `lwt_ppx`,
+    # as new Lwt releases may contain broken `lwt_ppx` code.
+    url = "https://github.com/ocsigen/lwt/archive/4.4.0.tar.gz";
+    sha256 = "1l97zdcql7y13fhaq0m9n9xvxf712jg0w70r72fvv6j49xm4nlhi";
+  };
 
-  inherit (lwt) src version;
 
   propagatedBuildInputs = [ lwt ppx_tools_versioned ];