ocamlPackages.menhir: support --suggest-menhirLib (#358146)

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

@@ -1,4 +1,4 @@
-{ buildDunePackage
+{ buildDunePackage, substituteAll, ocaml
 , menhirLib, menhirSdk
 }:
 
@@ -11,6 +11,13 @@ buildDunePackage rec {
 
   buildInputs = [ menhirLib menhirSdk ];
 
+  patches = [
+    (substituteAll {
+      src = ./menhir-suggest-menhirLib.patch;
+      libdir = "${menhirLib}/lib/ocaml/${ocaml.version}/site-lib/menhirLib";
+    })
+  ];
+
   meta = menhirSdk.meta // {
     description = "LR(1) parser generator for OCaml";
     mainProgram = "menhir";

pkgs/development/ocaml-modules/menhir/menhir-suggest-menhirLib.patch

@@ -0,0 +1,19 @@
+diff --git a/src/installation.ml b/src/installation.ml
+index 3c64e395..be7d6e7b 100644
+--- a/src/installation.ml
++++ b/src/installation.ml
+@@ -39,13 +39,4 @@ let rec normalize fn =
+    and hope that it is of the form [.../bin/menhir]. We change this to
+    [.../lib/menhirLib], and hope that this is where MenhirLib is installed. *)
+ 
+-let libdir () =
+-  let root =
+-    Sys.executable_name
+-    |> normalize
+-    |> Filename.dirname (* remove [menhir] *)
+-    |> Filename.dirname (* remove [bin] *)
+-  in
+-  Filename.concat
+-    root
+-    (Filename.concat "lib" "menhirLib")
++let libdir () = ignore normalize; "@libdir@"