ocamlPackages.ppxlib: Add version 0.18.0

The default version is still 0.15.0 to avoid breaking other packages.

pkgs/development/ocaml-modules/ppxlib/default.nix

@@ -1,21 +1,29 @@
 { lib, fetchFromGitHub, buildDunePackage, ocaml
 , version ? if lib.versionAtLeast ocaml.version "4.07" then "0.15.0" else "0.13.0"
 , ocaml-compiler-libs, ocaml-migrate-parsetree, ppx_derivers, stdio
-, stdlib-shims
+, stdlib-shims, ocaml-migrate-parsetree-2-1
 }:
 
 let param = {
   "0.8.1" = {
     sha256 = "0vm0jajmg8135scbg0x60ivyy5gzv4abwnl7zls2mrw23ac6kml6";
     max_version = "4.10";
+    useDune2 = false;
+    useOMP2 = false;
   };
   "0.13.0" = {
     sha256 = "0c54g22pm6lhfh3f7s5wbah8y48lr5lj3cqsbvgi99bly1b5vqvl";
+    useDune2 = false;
+    useOMP2 = false;
   };
   "0.15.0" = {
     sha256 = "1p037kqj5858xrhh0dps6vbf4fnijla6z9fjz5zigvnqp4i2xkrn";
     min_version = "4.07";
-    useDune2 = true;
+    useOMP2 = false;
+  };
+  "0.18.0" = {
+    sha256 = "1ciy6va2gjrpjs02kha83pzh0x1gkmfsfsdgabbs1v14a8qgfibm";
+    min_version = "4.07";
   };
 }."${version}"; in
 
@@ -28,7 +36,7 @@ buildDunePackage rec {
   pname = "ppxlib";
   inherit version;
 
-  useDune2 = param.useDune2 or false;
+  useDune2 = param.useDune2 or true;
 
   src = fetchFromGitHub {
     owner = "ocaml-ppx";
@@ -38,7 +46,12 @@ buildDunePackage rec {
   };
 
   propagatedBuildInputs = [
-    ocaml-compiler-libs ocaml-migrate-parsetree ppx_derivers stdio
+    ocaml-compiler-libs
+    (if param.useOMP2 or true
+     then ocaml-migrate-parsetree-2-1
+     else ocaml-migrate-parsetree)
+    ppx_derivers
+    stdio
     stdlib-shims
   ];