pkg: Show git error messages in Rev_store fetch_object

Signed-off-by: Puneeth Chaganti <[email protected]>

Author: punchagan

src/dune_pkg/opamUrl0.ml

@@ -52,12 +52,14 @@ type resolve =
   | Resolved of Rev_store.Object.resolved
   | Unresolved of Rev_store.Object.t
 
-let not_found t =
+let not_found ~git_output t =
   let url = base_url t in
   let rev = rev t in
+  let git_output = List.map ~f:Pp.verbatim git_output in
   Error
     (User_message.make
-       [ (match rev with
+     @@ git_output
+     @ [ (match rev with
           | None -> Pp.textf "default branch not found in %s" url
           | Some rev -> Pp.textf "revision %S not found in %s" rev url)
        ])
@@ -89,7 +91,7 @@ let resolve t ~loc rev_store =
   | `Ref revision ->
     Rev_store.resolve_revision rev_store remote ~revision
     >>| (function
-     | None -> not_found t
+     | None -> not_found ~git_output:[] t
      | Some o -> Ok (Resolved o))
 ;;
 
@@ -101,8 +103,8 @@ let fetch_revision t ~loc resolve rev_store =
   | Unresolved o ->
     Rev_store.fetch_object rev_store remote o
     >>| (function
-     | None -> not_found t
-     | Some rev -> Ok rev)
+     | Error git_output -> not_found ~git_output t
+     | Ok rev -> Ok rev)
 ;;
 
 let set_rev (t : t) rev = { t with hash = Some (Rev_store.Object.to_hex rev) }

src/dune_pkg/rev_store.ml

@@ -1163,8 +1163,8 @@ let resolve_revision t (remote : Remote.t) ~revision =
 let fetch_object t (remote : Remote.t) revision =
   fetch_allow_failure t ~url:remote.url revision
   >>= function
-  | `Not_found _ -> Fiber.return None
-  | `Fetched -> At_rev.of_rev t ~revision >>| Option.some
+  | `Not_found git_output -> Fiber.return (Error git_output)
+  | `Fetched -> At_rev.of_rev t ~revision >>| Result.ok
 ;;
 
 let content_of_files t files =

src/dune_pkg/rev_store.mli

@@ -104,10 +104,10 @@ end
 val resolve_revision : t -> Remote.t -> revision:string -> Object.resolved option Fiber.t
 
 (** [fetch_object t remote object] ensures that an [object] from the [remote]
-    is present in the revision store [t]. If the reviison is already present,
-    no network I/O is performed. Returns [None] if the remote reports "not
-    found". *)
-val fetch_object : t -> Remote.t -> Object.t -> At_rev.t option Fiber.t
+    is present in the revision store [t]. If the revision is already present,
+    no network I/O is performed. Returns [Error git_error_lines] if the remote
+    reports "not found". *)
+val fetch_object : t -> Remote.t -> Object.t -> (At_rev.t, string list) result Fiber.t
 
 (** Fetch the file contents of the repository at the given revision into the
     store and return the repository view. *)

test/expect-tests/dune_pkg/rev_store_tests.ml

@@ -117,8 +117,9 @@ let%expect_test "fetching an object twice from the store" =
       Rev_store.Object.of_sha1 remote_revision
       |> Option.value_exn
       |> Rev_store.fetch_object rev_store remote
-      >>| Option.value_exn
+      >>| Result.to_option
     in
+    let at_rev = Option.value_exn at_rev in
     Rev_store.At_rev.directory_entries at_rev ~recursive:true Path.Local.root
     |> Rev_store.File.Set.find ~f:(fun f ->
       Path.Local.equal (Rev_store.File.path f) (Path.Local.of_string file))