Simplified discover.ml

Author: mmottl

src/config/discover.ml

@@ -55,34 +55,19 @@ let major_minor_from_pgconfig () =
   in
   Fun.protect ~finally:(fun () -> close_in ic) (fun () -> pg_major_minor ic)
 
-let major_minor_from_pkg_config =
-  let pkg_config_prefix () =
-    let pkg_config_args =
-      match Sys.getenv "PKG_CONFIG_ARGN" with
-      | s -> String.split_on_char ' ' s
-      | exception Not_found -> []
-    in
-    let bin =
-      match Sys.getenv "PKG_CONFIG" with
-      | s -> s
-      | exception Not_found -> "pkg-config"
-    in
-    Format.asprintf "%s %s " bin (String.concat " " pkg_config_args)
-  in
-  fun () ->
-    let ic =
-      Unix.open_process_in (pkg_config_prefix () ^ " --modversion libpq")
-    in
-    Fun.protect ~finally:(fun () -> close_in ic) @@ fun () ->
-    let version_line = input_line ic in
-    (* Typically something like "14.1" *)
-    match String.split_on_char '.' version_line with
-    | major :: minor :: _ ->
-        ( "-DPG_OCAML_MAJOR_VERSION=" ^ major,
-          "-DPG_OCAML_MINOR_VERSION=" ^ minor )
-    | _ ->
-        eprintf "Unable to parse libpq version: %s" version_line;
-        exit 1
+let major_minor_from_pkg_config () =
+  let bin = Sys.getenv_opt "PKG_CONFIG" |> Option.value ~default:"pkg-config" in
+  let args = Sys.getenv_opt "PKG_CONFIG_ARGN" |> Option.value ~default:"" in
+  let cmd = Format.asprintf "%s %s --modversion libpq" bin args in
+  let ic = Unix.open_process_in cmd in
+  Fun.protect ~finally:(fun () -> close_in ic) @@ fun () ->
+  let version_line = input_line ic in
+  match String.split_on_char '.' version_line with
+  | major :: minor :: _ ->
+      ("-DPG_OCAML_MAJOR_VERSION=" ^ major, "-DPG_OCAML_MINOR_VERSION=" ^ minor)
+  | _ ->
+      eprintf "Unable to parse libpq version: %s" version_line;
+      exit 1
 
 let from_pgconfig () =
   let cmd = "pg_config --includedir --libdir --version" in