Add myocamlbuild.ml which defines OCAML_VERSION for cppo.

myocamlbuild.ml

@@ -0,0 +1,46 @@
+(* OASIS_START *)
+(* OASIS_STOP *)
+
+open Ocamlbuild_plugin;;
+
+dispatch
+  (MyOCamlbuildBase.dispatch_combine [
+    begin function
+    | After_rules ->
+      (* replace with Ocamlbuild_cppo.dispatch when 4.00 is not supported
+         anymore *)
+      let dep = "%(name).cppo.ml" in
+      let prod1 = "%(name: <*> and not <*.cppo>).ml" in
+      let prod2 = "%(name: <**/*> and not <**/*.cppo>).ml" in
+      let f prod env _build =
+        let dep = env dep in
+        let prod = env prod in
+        let tags = tags_of_pathname prod ++ "cppo" in
+        Cmd (S[A "cppo"; T tags; S [A "-o"; P prod]; P dep ])
+      in
+      rule "cppo1" ~dep ~prod:prod1 (f prod1) ;
+      rule "cppo2" ~dep ~prod:prod2 (f prod2) ;
+      pflag ["cppo"] "cppo_D" (fun s -> S [A "-D"; A s]) ;
+      pflag ["cppo"] "cppo_U" (fun s -> S [A "-U"; A s]) ;
+      pflag ["cppo"] "cppo_I" (fun s ->
+        if Pathname.is_directory s then S [A "-I"; P s]
+        else S [A "-I"; P (Pathname.dirname s)]
+      ) ;
+      pdep ["cppo"] "cppo_I" (fun s ->
+        if Pathname.is_directory s then [] else [s]) ;
+      flag ["cppo"; "cppo_q"] (A "-q") ;
+      flag ["cppo"; "cppo_s"] (A "-s") ;
+      flag ["cppo"; "cppo_n"] (A "-n") ;
+      pflag ["cppo"] "cppo_x" (fun s -> S [A "-x"; A s]);
+      (* end replace *)
+
+      let ocaml_version =
+        Scanf.sscanf Sys.ocaml_version "%d.%d.%d" (fun major minor patchlevel ->
+        (* e.g. #define OCAML_VERSION 040201 *)
+        Printf.sprintf "OCAML_VERSION %d" (major * 10000 + minor * 100 + patchlevel))
+      in
+      flag ["cppo"] & S[A"-D"; A ocaml_version]
+    | _ -> ()
+    end;
+    dispatch_default
+  ])