Support new locations of unix, str and dynlink

src/ocaml_specific.ml

@@ -819,9 +819,19 @@ camlp4_flags' ["camlp4orr", S[A"camlp4of"; A"-parser"; A"reloaded"];
 
 flag ["ocaml"; "pp"; "camlp4:no_quot"] (A"-no_quot");;
 
-ocaml_lib ~extern:true "dynlink";;
-ocaml_lib ~extern:true "unix";;
-ocaml_lib ~extern:true "str";;
+let ocaml_otherlibs_lib =
+  match split_ocaml_version with
+  | Some (major, minor, _, _) when (major, minor) >= (5, 0) ->
+    fun name ->
+      let dir = "+" ^ name in
+      ocaml_lib ~extern:true ~dir name;
+      flag ["ocaml"; "compile"; "use_" ^ name] (S[A"-I"; A dir])
+  | _ ->
+    fun name -> ocaml_lib ~extern:true name;;
+
+ocaml_otherlibs_lib "dynlink";;
+ocaml_otherlibs_lib "unix";;
+ocaml_otherlibs_lib "str";;
 ocaml_lib ~extern:true "bigarray";;
 ocaml_lib ~extern:true "nums";;
 ocaml_lib ~extern:true "dbm";;

src/plugin.ml

@@ -175,7 +175,12 @@ module Make(U:sig end) =
           let unix_lib =
             if use_ocamlfind_pkgs then `Package "unix"
             else if use_light_mode then `Nothing
-            else `Lib "unix" in
+            else let dir = match split_ocaml_version with
+                 | Some (major, minor, _, _) when (major, minor) >= (5, 0) ->
+                    Some "unix"
+                 | _ -> None
+                 in
+                 `Lib ("unix", dir) in
 
           let ocamlbuild_lib =
             if use_ocamlfind_pkgs then `Package "ocamlbuild"
@@ -198,7 +203,8 @@ module Make(U:sig end) =
           let spec = function
             | `Nothing -> N
             | `Package pkg -> S[A "-package"; A pkg]
-            | `Lib lib -> P (lib -.- cma)
+            | `Lib (lib, Some dir) -> S[A "-I"; A ("+" ^ dir); P (lib -.- cma)]
+            | `Lib (lib, None) -> P (lib -.- cma)
             | `Local_lib llib -> S [A "-I"; A dir; P (in_dir (llib -.- cma))]
             | `Local_mod lmod -> P (in_dir (lmod -.- cmo)) in