From 6252cc6e34678f54917d03b68887f98c6c50b8b0 Mon Sep 17 00:00:00 2001
From: Jeremie Dimino <jeremie@dimino.org>
Date: Fri, 11 May 2018 15:44:47 +0200
Subject: [PATCH] Auto-detect ppx_sexp_conv runtime library

---
 myocamlbuild.ml       | 25 ++++++++++++++++++++++---
 pkg/{META => META.in} |  2 +-
 2 files changed, 23 insertions(+), 4 deletions(-)
 rename pkg/{META => META.in} (95%)

diff --git a/myocamlbuild.ml b/myocamlbuild.ml
index 8fcbe33..95f4051 100644
--- a/myocamlbuild.ml
+++ b/myocamlbuild.ml
@@ -1,5 +1,24 @@
 open Ocamlbuild_plugin
 
-let () = dispatch Ocb_stubblr.(
-  init & ccopt ~tags:["accelerate"] "-DACCELERATE -mssse3 -maes -mpclmul"
-)
+let runtime_deps_of_ppx ppx =
+  (Findlib.query "ppx_sexp_conv").dependencies
+  |> List.filter_opt (fun { Findlib.name; _ } ->
+      if name = ppx || name = "ppx_deriving" then
+        None
+      else
+        Some name)
+
+let () = dispatch (fun hook ->
+    Ocb_stubblr.(
+      init & ccopt ~tags:["accelerate"] "-DACCELERATE -mssse3 -maes -mpclmul"
+    ) hook;
+    match hook with
+    | After_rules ->
+      let meta = "pkg/META" in
+      let meta_in = meta ^ ".in" in
+      rule meta ~dep:meta_in ~prod:meta (fun _ _ ->
+          let deps = String.concat " " (runtime_deps_of_ppx "ppx_sexp_conv") in
+          Echo([String.subst "PPX_SEXP_CONV_RUNTIME" deps
+                  (Pathname.read meta_in)],
+               meta))
+    | _ -> ())
diff --git a/pkg/META b/pkg/META.in
similarity index 95%
rename from pkg/META
rename to pkg/META.in
index 64a1dbf..c633212 100644
--- a/pkg/META
+++ b/pkg/META.in
@@ -1,6 +1,6 @@
 version = "%%VERSION_NUM%%"
 description = "Simple crypto for the modern age"
-requires = "cstruct zarith sexplib"
+requires = "cstruct zarith sexplib PPX_SEXP_CONV_RUNTIME"
 archive(byte) = "nocrypto.cma"
 archive(native) = "nocrypto.cmxa"
 plugin(byte) = "nocrypto.cma"