fix(x-compilation): take the default findlib path context into account

Signed-off-by: Antonio Nuno Monteiro <[email protected]>

src/dune_rules/context.ml

@@ -299,26 +299,23 @@ module Build_environment_kind = struct
           | None -> Unknown)))
 
   let findlib_paths ocamlfind ~kind ~context ~findlib_toolchain ~env ~dir =
-    match query ~kind ~findlib_toolchain ~env with
-    | Cross_compilation_using_findlib_toolchain _toolchain -> (
-      match ocamlfind with
-      | None ->
-        Code_error.raise
-          "Could not find ocamlfind in PATH or an environment variable \
-           OCAMLFIND_CONF"
-          [ ("context", Context_name.to_dyn context) ]
-      | Some ocamlfind -> Ocamlfind.conf_path ocamlfind)
-    | Hardcoded_path l -> List.map l ~f:Path.of_filename_relative_to_initial_cwd
-    | Opam2_environment opam_prefix ->
+    match (ocamlfind, query ~kind ~findlib_toolchain ~env) with
+    | ( Some ocamlfind
+      , ( Cross_compilation_using_findlib_toolchain _
+        | Opam2_environment _
+        | Unknown ) ) -> Ocamlfind.conf_path ocamlfind
+    | None, Cross_compilation_using_findlib_toolchain _toolchain ->
+      Code_error.raise
+        "Could not find ocamlfind in PATH or an environment variable \
+         OCAMLFIND_CONF"
+        [ ("context", Context_name.to_dyn context) ]
+    | _, Hardcoded_path l ->
+      List.map l ~f:Path.of_filename_relative_to_initial_cwd
+    | None, Opam2_environment opam_prefix ->
       let p = Path.of_filename_relative_to_initial_cwd opam_prefix in
       let p = Path.relative p "lib" in
       [ p ]
-    | Unknown -> (
-      match ocamlfind with
-      | None ->
-        (* TODO? *)
-        [ Path.relative (Path.parent_exn dir) "lib" ]
-      | Some ocamlfind -> Ocamlfind.conf_path ocamlfind)
+    | None, Unknown -> [ Path.relative (Path.parent_exn dir) "lib" ]
 end
 
 let check_fdo_support has_native ocfg ~name =
@@ -359,20 +356,14 @@ type instance =
 let create ~(kind : Kind.t) ~path ~env ~env_nodes ~name ~merlin ~targets
     ~host_context ~host_toolchain ~profile ~fdo_target_exe
     ~dynamically_linked_foreign_archives ~instrument_with =
-  let prog_not_found_in_path prog =
-    Utils.program_not_found prog ~context:name ~loc:None
-  in
   let which = Program.which ~path in
-
   let env_ocamlpath = Ocamlfind.ocamlpath env in
   let ocamlpath =
     let initial_ocamlpath = Ocamlfind.ocamlpath Env.initial in
     match (env_ocamlpath, initial_ocamlpath) with
     | [], [] -> []
     | _ :: _, [] -> env_ocamlpath
-    | [], _ :: _ ->
-      (* TODO? *)
-      initial_ocamlpath
+    | [], _ :: _ -> initial_ocamlpath
     | _, _ -> (
       match
         List.compare ~compare:Path.compare env_ocamlpath initial_ocamlpath
@@ -388,29 +379,20 @@ let create ~(kind : Kind.t) ~path ~env ~env_nodes ~name ~merlin ~targets
       | Default, None -> env_ocamlpath
       | _, _ -> ocamlpath
     in
-
     let* ocamlfind =
-      Ocamlfind.discover_from_env ~env ~ocamlpath ~which >>| function
-      | None -> None
-      | Some ocamlfind ->
-        Some
-          (match findlib_toolchain with
-          | None -> ocamlfind
-          | Some toolchain ->
-            let toolchain = Context_name.to_string toolchain in
-            Ocamlfind.set_toolchain ocamlfind ~toolchain)
+      Ocamlfind.discover_from_env ~env ~which ~ocamlpath ~findlib_toolchain
     in
-
     let get_tool_using_findlib_config prog =
       Memo.Option.bind ocamlfind ~f:(Ocamlfind.tool ~prog)
     in
     let* ocamlc =
-      get_tool_using_findlib_config "ocamlc" >>= function
+      let ocamlc = "ocamlc" in
+      get_tool_using_findlib_config ocamlc >>= function
       | Some x -> Memo.return x
       | None -> (
-        which "ocamlc" >>| function
+        which ocamlc >>| function
         | Some x -> x
-        | None -> prog_not_found_in_path "ocamlc")
+        | None -> Utils.program_not_found ocamlc ~context:name ~loc:None)
     in
     let dir = Path.parent_exn ocamlc in
     let get_ocaml_tool prog =

src/dune_rules/findlib/findlib.ml

@@ -100,7 +100,7 @@ module Vars = struct
 
   let empty = String.Map.empty
 
-  let superpose = String.Map.superpose
+  let union = String.Map.union
 end
 
 module Config = struct
@@ -116,7 +116,6 @@ module Config = struct
       ; ("preds", Ps.to_dyn preds)
       ]
 
-
   let load config_file =
     let load p =
       let+ meta = Meta.load ~name:None p in
@@ -141,7 +140,12 @@ module Config = struct
                 let p = Path.Outside_build_dir.relative config_dir p in
                 load p)
           in
-          List.fold_left all_vars ~init:vars ~f:Vars.superpose
+          List.fold_left all_vars ~init:vars ~f:(fun acc vars ->
+              Vars.union acc vars ~f:(fun _ (x : Rules.t) y ->
+                  Some
+                    { Rules.set_rules = x.set_rules @ y.set_rules
+                    ; add_rules = x.add_rules @ y.add_rules
+                    }))
         | Error _ -> Memo.return vars)
       | Ok false | Error _ -> Memo.return vars
     in

src/dune_rules/findlib/ocamlfind.ml

@@ -19,8 +19,6 @@ let ocamlpath env =
   | None -> []
   | Some s -> path_var s
 
-let toolchain t = t.toolchain
-
 let set_toolchain t ~toolchain =
   match t.toolchain with
   | None ->
@@ -55,29 +53,40 @@ let tool t ~prog =
     | Absolute ->
       Memo.return (Some (Path.of_filename_relative_to_initial_cwd s)))
 
-let ocamlfind_config_path ~env ~which =
-  Memo.lazy_ ~cutoff:(Option.equal Path.External.equal) (fun () ->
-      let open Memo.O in
-      let+ path =
-        match Env.get env "OCAMLFIND_CONF" with
-        | Some s -> Memo.return (Some s)
-        | None -> (
-          which "ocamlfind" >>= function
-          | None -> Memo.return None
-          | Some fn ->
-            Memo.of_reproducible_fiber
-              (Process.run_capture_line ~display:Quiet ~env Strict fn
-                 [ "printconf"; "conf" ])
-            |> Memo.map ~f:Option.some)
-      in
-      Option.map path ~f:Path.External.of_filename_relative_to_initial_cwd)
+let ocamlfind_config_path ~env ~which ~findlib_toolchain =
+  let open Memo.O in
+  let+ path =
+    match Env.get env "OCAMLFIND_CONF" with
+    | Some s -> Memo.return (Some s)
+    | None -> (
+      match findlib_toolchain with
+      | None -> Memo.return None
+      | Some _ -> (
+        which "ocamlfind" >>= function
+        | None -> Memo.return None
+        | Some fn ->
+          Memo.of_reproducible_fiber
+            (Process.run_capture_line ~display:Quiet ~env Strict fn
+               [ "printconf"; "conf" ])
+          |> Memo.map ~f:Option.some))
+  in
+  (* From http://projects.camlcity.org/projects/dl/findlib-1.9.6/doc/ref-html/r865.html
+     This variable overrides the location of the configuration file
+     findlib.conf. It must contain the absolute path name of this file. *)
+  Option.map path ~f:Path.External.of_string
 
-let discover_from_env ~env ~ocamlpath ~which =
+let discover_from_env ~env ~which ~ocamlpath ~findlib_toolchain =
   let open Memo.O in
-  Memo.Lazy.force (ocamlfind_config_path ~env ~which) >>= function
+  ocamlfind_config_path ~env ~which ~findlib_toolchain >>= function
   | None -> Memo.return None
   | Some config ->
     let+ config = Findlib.Config.load (External config) in
-    Some { config; ocamlpath; which; toolchain = None }
+    let base = { config; ocamlpath; which; toolchain = None } in
+    Some
+      (match findlib_toolchain with
+      | None -> base
+      | Some toolchain ->
+        let toolchain = Context_name.to_string toolchain in
+        set_toolchain base ~toolchain)
 
 let extra_env t = Findlib.Config.env t.config

src/dune_rules/findlib/ocamlfind.mli

@@ -4,20 +4,17 @@ type t
 
 val conf_path : t -> Path.t list
 
-val discover_from_env :
-     env:Env.t
-  -> ocamlpath:Path.t list
-  -> which:(string -> Path.t option Memo.t)
-  -> t option Memo.t
-
 val tool : t -> prog:string -> Path.t option Memo.t
 
 val ocamlpath_sep : char
 
 val ocamlpath : Env.t -> Path.t list
 
-val toolchain : t -> string option
-
-val set_toolchain : t -> toolchain:string -> t
-
 val extra_env : t -> Env.t
+
+val discover_from_env :
+     env:Env.t
+  -> which:(string -> Path.t option Memo.t)
+  -> ocamlpath:Path.t list
+  -> findlib_toolchain:Dune_engine.Context_name.t option
+  -> t option Memo.t

test/blackbox-tests/test-cases/custom-cross-compilation/cross-compilation-ocamlfind.t

@@ -63,17 +63,24 @@ Dune should be able to find it too
 
   $ dune build --root=app @install -x foo
   Entering directory 'app'
-  File "dune", line 6, characters 12-18:
-  6 |  (libraries libdep))
-                  ^^^^^^
-  Error: Library "libdep" not found.
-  -> required by _build/default/.gen.eobjs/byte/dune__exe__Gen.cmi
-  -> required by _build/default/.gen.eobjs/native/dune__exe__Gen.cmx
-  -> required by _build/default/gen.exe
-  -> required by _build/default.foo/foo.ml
-  -> required by _build/install/default.foo/lib/repro/foo.ml
-  -> required by _build/default.foo/repro-foo.install
-  -> required by alias install (context default.foo)
   Leaving directory 'app'
-  [1]
 
+Library is built in the target context
+
+  $ ls app/_build/default.foo
+  META.repro
+  foo.ml
+  repro-foo.install
+  repro.a
+  repro.cma
+  repro.cmxa
+  repro.cmxs
+  repro.dune-package
+  repro.ml-gen
+
+Executable was built in the host context
+
+  $ ls app/_build/default
+  gen.exe
+  gen.ml
+  gen.mli