Improved error message running pg_config

Author: mmottl

src/config/discover.ml

@@ -5,57 +5,60 @@ let () =
   let module C = Configurator in
   C.main ~name:"postgresql" (fun _c ->
     let cmd = "pg_config --includedir --libdir --version" in
-    Exn.protectx (Unix.open_process_in cmd) ~finally:In_channel.close
-      ~f:(fun ic ->
-        let pgsql_includedir = "-I" ^ In_channel.input_line_exn ic in
-        let pgsql_libdir = "-L" ^ In_channel.input_line_exn ic in
-        let major, minor =
-          let line = In_channel.input_line_exn ic in
-          let print_fail () =
-            eprintf "Unable to find versions from line '%s', cmd: '%s'" line cmd
+    let ic =
+      try Unix.open_process_in cmd
+      with exc -> eprintf "could not open pg_config, cmd: '%s'" cmd; raise exc
+    in
+    Exn.protectx ic ~finally:In_channel.close ~f:(fun ic ->
+      let pgsql_includedir = "-I" ^ In_channel.input_line_exn ic in
+      let pgsql_libdir = "-L" ^ In_channel.input_line_exn ic in
+      let major, minor =
+        let line = In_channel.input_line_exn ic in
+        let print_fail () =
+          eprintf "Unable to find versions from line '%s', cmd: '%s'" line cmd
+        in
+        try
+          let first_space = String.index_exn line ' ' in
+          let first_dot = String.index_exn line '.' in
+          let first_part =
+            let len = first_dot - first_space - 1 in
+            String.sub line ~pos:(first_space + 1) ~len
           in
-          try
-            let first_space = String.index_exn line ' ' in
-            let first_dot = String.index_exn line '.' in
-            let first_part =
-              let len = first_dot - first_space - 1 in
-              String.sub line ~pos:(first_space + 1) ~len
-            in
-            let second_part =
-              let len = String.length line - first_dot - 1 in
-              String.sub line ~pos:(first_dot + 1) ~len
-            in
-            let search_version s =
-              let version = ref "" in
-              let stop = ref false in
-              let check_car c =
-                let ascii = Char.to_int c in
-                if (ascii >= 48 && ascii <= 57 && not !stop) then
-                  version := !version ^ (String.make 1 c)
-                else stop := true
-              in
-              let () = String.iter ~f:check_car s in
-              !version
+          let second_part =
+            let len = String.length line - first_dot - 1 in
+            String.sub line ~pos:(first_dot + 1) ~len
+          in
+          let search_version s =
+            let version = ref "" in
+            let stop = ref false in
+            let check_car c =
+              let ascii = Char.to_int c in
+              if (ascii >= 48 && ascii <= 57 && not !stop) then
+                version := !version ^ (String.make 1 c)
+              else stop := true
             in
-            let major = search_version first_part in
-            let minor = search_version second_part in
-            if String.(major <> "" && minor <> "") then
-              "-DPG_OCAML_MAJOR_VERSION=" ^ major,
-              "-DPG_OCAML_MINOR_VERSION=" ^ minor
-            else begin
-              print_fail ();
-              Caml.exit 1
-            end
-          with exn -> print_fail (); raise exn
-        in
-        let conf = {
-          C.Pkg_config.
-          cflags = [pgsql_includedir; major; minor];
-          libs = [pgsql_libdir; "-lpq"];
-        } in
-        let write_sexp file sexp =
-          Out_channel.write_all file ~data:(Sexp.to_string sexp)
-        in
-        write_sexp "c_flags.sexp" (sexp_of_list sexp_of_string conf.cflags);
-        write_sexp "c_library_flags.sexp"
-          (sexp_of_list sexp_of_string conf.libs)))
+            let () = String.iter ~f:check_car s in
+            !version
+          in
+          let major = search_version first_part in
+          let minor = search_version second_part in
+          if String.(major <> "" && minor <> "") then
+            "-DPG_OCAML_MAJOR_VERSION=" ^ major,
+            "-DPG_OCAML_MINOR_VERSION=" ^ minor
+          else begin
+            print_fail ();
+            Caml.exit 1
+          end
+        with exn -> print_fail (); raise exn
+      in
+      let conf = {
+        C.Pkg_config.
+        cflags = [pgsql_includedir; major; minor];
+        libs = [pgsql_libdir; "-lpq"];
+      } in
+      let write_sexp file sexp =
+        Out_channel.write_all file ~data:(Sexp.to_string sexp)
+      in
+      write_sexp "c_flags.sexp" (sexp_of_list sexp_of_string conf.cflags);
+      write_sexp "c_library_flags.sexp"
+        (sexp_of_list sexp_of_string conf.libs)))