use the compiler META files when available

Octachron · dra27 · commit fec8a08bcaef · 2022-06-20T10:55:36.000+01:00
Signed-off-by: David Allsopp &lt;david.allsopp@metastack.com&gt;
diff --git a/src/dune_rules/context.ml b/src/dune_rules/context.ml
@@ -482,8 +482,14 @@ let create ~(kind : Kind.t) ~path ~env ~env_nodes ~name ~merlin ~targets
               (vars, ocfg)
             | Error msg -> Error (Ocamlc_config, msg)))
     in
-    let findlib_paths = ocamlpath @ default_ocamlpath in
+    let stdlib_dir = Path.of_string (Ocaml_config.standard_library ocfg) in
     let version = Ocaml.Version.of_ocaml_config ocfg in
+    let default_ocamlpath =
+      if Ocaml.Version.has_META_files version then
+        stdlib_dir :: default_ocamlpath
+      else default_ocamlpath
+    in
+    let findlib_paths = ocamlpath @ default_ocamlpath in
     let env =
       (* See comment in ansi_color.ml for setup_env_for_colors. For versions
          where OCAML_COLOR is not supported, but 'color' is in OCAMLPARAM, use
@@ -547,7 +553,6 @@ let create ~(kind : Kind.t) ~path ~env ~env_nodes ~name ~merlin ~targets
               (Option.map findlib_config ~f:Findlib.Config.env))
       |> Env.extend_env (Env_nodes.extra_env ~profile env_nodes)
     in
-    let stdlib_dir = Path.of_string (Ocaml_config.standard_library ocfg) in
     let natdynlink_supported = Ocaml_config.natdynlink_supported ocfg in
     let arch_sixtyfour = Ocaml_config.word_size ocfg = 64 in
     let* ocamlopt = get_ocaml_tool "ocamlopt" in
diff --git a/src/dune_rules/findlib/meta.ml b/src/dune_rules/findlib/meta.ml
@@ -159,7 +159,7 @@ let main_modules names =
   List.map ~f:String.capitalize_ascii names
   |> String.concat ~sep:" " |> rule "main_modules" [] Set
 
-let builtins ~stdlib_dir ~version:ocaml_version =
+let pre_ocaml_5_builtins ~stdlib_dir ~version:ocaml_version =
   let version = version "[distributed with OCaml]" in
   let simple name ?(labels = false) ?dir ?archive_name ?kind ?exists_if_ext deps
       =
@@ -302,6 +302,11 @@ let builtins ~stdlib_dir ~version:ocaml_version =
           (Lib_name.package_name name, simplify t)))
   |> Package.Name.Map.of_list_exn
 
+let builtins ~stdlib_dir ~version =
+  if Ocaml.Version.has_META_files version then
+    Memo.return Package.Name.Map.empty
+  else pre_ocaml_5_builtins ~stdlib_dir ~version
+
 let string_of_action = function
   | Set -> "="
   | Add -> "+="
diff --git a/src/ocaml/version.ml b/src/ocaml/version.ml
@@ -47,3 +47,5 @@ let has_bigarray_library version = version < (5, 0, 0)
 let supports_alerts version = version >= (4, 8, 0)
 
 let has_sandboxed_otherlibs version = version >= (5, 0, 0)
+
+let has_META_files version = version >= (5, 0, 0)
diff --git a/src/ocaml/version.mli b/src/ocaml/version.mli
@@ -71,3 +71,6 @@ val supports_alerts : t -> bool
 (** Whether [dynlink], [str] and [unix] are in subdirectories of the standard
     library *)
 val has_sandboxed_otherlibs : t -> bool
+
+(** Whether the compiler distributes META files independently of ocamlfind *)
+val has_META_files : t -> bool
