ocaml · Feb 25, 2021 · Feb 24, 2021 · Feb 25, 2021
diff --git a/CHANGES.md b/CHANGES.md
@@ -65,6 +65,10 @@ Unreleased
 
 - Enable cram tests by default (#4262, @rgrinberg)
 
+- Stop calling `ocamlfind` to determine the library search path or
+  library installation directory. This makes the behavior of Dune
+  simpler and more reproducible (#...., @jeremiedimino)
+
 2.8.2 (21/01/2021)
 ------------------
 

diff --git a/bin/install_uninstall.ml b/bin/install_uninstall.ml
@@ -19,12 +19,11 @@ let get_dirs context ~prefix_from_command_line ~libdir_from_command_line =
   | None ->
     let open Fiber.O in
     let* prefix = Context.install_prefix context in
-    let libdir =
+    let+ libdir =
       match libdir_from_command_line with
       | None -> Memo.Build.run (Context.install_ocaml_libdir context)
       | Some l -> Fiber.return (Some (Path.relative prefix l))
     in
-    let+ libdir = libdir in
     (prefix, libdir)
 
 let resolve_package_install setup pkg =

diff --git a/doc/usage.rst b/doc/usage.rst
@@ -302,17 +302,24 @@ Finding external libraries
 When a library is not available in the workspace, dune will look it
 up in the installed world, and expect it to be already compiled.
 
-It looks up external libraries using a specific list of search paths. A
-list of search paths is specific to a given build context and is
-determined as follows:
-
-#. if the ``ocamlfind`` is present in the ``PATH`` of the context, use each line
-   in the output of ``ocamlfind printconf path`` as a search path
-#. otherwise, if ``opam`` is present in the ``PATH``, use the output of ``opam
-   config var lib``
-#. otherwise, take the directory where ``ocamlc`` was found, and append
-   ``../lib`` to it. For instance if ``ocamlc`` is found in ``/usr/bin``, use
-   ``/usr/lib``
+It looks up external libraries using a specific list of search paths
+and each build context has a specific list of search paths.
+
+When running inside an opam environment, Dune will look for installed
+libraries in ``$OPAM_SWITCH_PREFIX/lib``. This includes both opam
+build context configured via the ``dune-workspace`` file and the
+default build context when the variable ``$OPAM_SWITCH_PREFIX`` is
+set.
+
+Otherwise, Dune takes the directory where ``ocamlc`` was found, and
+append `../lib`` to it. For instance if ``ocamlc`` is found in
+``/usr/bin``, Dune looks for installed libraries in ``/usr/lib``.
+
+In addition to the two above rules, Dune always inspect the
+``OCAMLPATH`` environment variable and use the paths defined in this
+variable. ``OCAMLPATH`` always has precedence and can have different
+value in different build contexts. For instance, you can set it
+manually in a specific build context via the ``dune-workspace`` file.
 
 .. _running-tests:
 

diff --git a/src/dune_rules/context.ml b/src/dune_rules/context.ml
@@ -467,7 +467,7 @@ let create ~(kind : Kind.t) ~path ~env ~env_nodes ~name ~merlin ~targets
       | None -> []
       | Some s -> Bin.parse_path s ~sep:ocamlpath_sep
     in
-    let default_findlib_paths () =
+    let default_library_search_path () =
       match Build_environment_kind.query ~kind ~findlib_toolchain ~env with
       | Cross_compilation_using_findlib_toolchain toolchain ->
         let ocamlfind = which_exn "ocamlfind" in
@@ -480,13 +480,8 @@ let create ~(kind : Kind.t) ~path ~env ~env_nodes ~name ~merlin ~targets
         let p = Path.of_filename_relative_to_initial_cwd opam_prefix in
         let p = Path.relative p "lib" in
         Memo.Build.return [ p ]
-      | Unknown -> (
-        match which "ocamlfind" with
-        | Some ocamlfind ->
-          let env = Env.remove env ~var:"OCAMLPATH" in
-          ocamlfind_printconf_path ~env ~ocamlfind ~toolchain:None
-        | None ->
-          Memo.Build.return [ Path.relative (Path.parent_exn dir) "lib" ] )
+      | Unknown ->
+        Memo.Build.return [ Path.relative (Path.parent_exn dir) "lib" ]
     in
     let ocaml_config_ok_exn = function
       | Ok x -> x
@@ -500,7 +495,7 @@ let create ~(kind : Kind.t) ~path ~env ~env_nodes ~name ~merlin ~targets
         User_error.raise ~loc:(Loc.in_file file) [ Pp.text msg ]
     in
     let* default_ocamlpath, (ocaml_config_vars, ocfg) =
-      Memo.Build.fork_and_join default_findlib_paths (fun () ->
+      Memo.Build.fork_and_join default_library_search_path (fun () ->
           let+ lines =
             Memo.Build.of_fiber
               (Process.run_capture_lines ~env Strict ocamlc [ "-config" ])
@@ -885,25 +880,10 @@ module DB = struct
 end
 
 let install_ocaml_libdir t =
-  match (t.kind, t.findlib_toolchain, Setup.library_destdir) with
-  | Default, None, Some d ->
+  match (t.kind, Setup.library_destdir) with
+  | Default, Some d ->
     Memo.Build.return (Some (Path.of_filename_relative_to_initial_cwd d))
-  | _ -> (
-    (* If ocamlfind is present, it has precedence over everything else. *)
-    match t.which "ocamlfind" with
-    | Some fn ->
-      let+ s =
-        Memo.Build.of_fiber
-          (Process.run_capture_line ~env:t.env Strict fn
-             [ "printconf"; "destdir" ])
-      in
-      let s = String.trim s in
-      if String.is_empty s then
-        (* This case happens if ocamlfind doesn't find its configuration file *)
-        None
-      else
-        Some (Path.of_filename_relative_to_initial_cwd s)
-    | None -> Memo.Build.return None )
+  | _ -> Memo.Build.return None
 
 let compiler t (mode : Mode.t) =
   match mode with

diff --git a/test/blackbox-tests/test-cases/install-libdir.t/run.t b/test/blackbox-tests/test-cases/install-libdir.t/run.t
@@ -85,56 +85,55 @@ If prefix is passed, the default for libdir is `$prefix/lib`:
   Creating directory install/man/man3
   Copying _build/install/default/man/man3/another-man-page.3 to install/man/man3/another-man-page.3 (executable: false)
 
-If prefix is not passed, libdir defaults to the output of `ocamlfind printconf
-destdir`:
+If prefix is not passed, libdir defaults to the opam-prefix/lib directory:
 
   $ (export OCAMLFIND_DESTDIR=/OCAMLFIND_DESTDIR
   >  dune install --dry-run 2>&1 | dune_cmd sanitize
   >  dune uninstall --dry-run 2>&1 | dune_cmd sanitize)
-  Removing (if it exists) /OCAMLFIND_DESTDIR/foo/META
-  Installing /OCAMLFIND_DESTDIR/foo/META
-  Creating directory /OCAMLFIND_DESTDIR/foo
-  Copying _build/install/default/lib/foo/META to /OCAMLFIND_DESTDIR/foo/META (executable: false)
-  Removing (if it exists) /OCAMLFIND_DESTDIR/foo/dune-package
-  Installing /OCAMLFIND_DESTDIR/foo/dune-package
-  Creating directory /OCAMLFIND_DESTDIR/foo
-  Copying _build/install/default/lib/foo/dune-package to /OCAMLFIND_DESTDIR/foo/dune-package (executable: false)
-  Removing (if it exists) /OCAMLFIND_DESTDIR/foo/foo$ext_lib
-  Installing /OCAMLFIND_DESTDIR/foo/foo$ext_lib
-  Creating directory /OCAMLFIND_DESTDIR/foo
-  Copying _build/install/default/lib/foo/foo$ext_lib to /OCAMLFIND_DESTDIR/foo/foo$ext_lib (executable: false)
-  Removing (if it exists) /OCAMLFIND_DESTDIR/foo/foo.cma
-  Installing /OCAMLFIND_DESTDIR/foo/foo.cma
-  Creating directory /OCAMLFIND_DESTDIR/foo
-  Copying _build/install/default/lib/foo/foo.cma to /OCAMLFIND_DESTDIR/foo/foo.cma (executable: false)
-  Removing (if it exists) /OCAMLFIND_DESTDIR/foo/foo.cmi
-  Installing /OCAMLFIND_DESTDIR/foo/foo.cmi
-  Creating directory /OCAMLFIND_DESTDIR/foo
-  Copying _build/install/default/lib/foo/foo.cmi to /OCAMLFIND_DESTDIR/foo/foo.cmi (executable: false)
-  Removing (if it exists) /OCAMLFIND_DESTDIR/foo/foo.cmt
-  Installing /OCAMLFIND_DESTDIR/foo/foo.cmt
-  Creating directory /OCAMLFIND_DESTDIR/foo
-  Copying _build/install/default/lib/foo/foo.cmt to /OCAMLFIND_DESTDIR/foo/foo.cmt (executable: false)
-  Removing (if it exists) /OCAMLFIND_DESTDIR/foo/foo.cmx
-  Installing /OCAMLFIND_DESTDIR/foo/foo.cmx
-  Creating directory /OCAMLFIND_DESTDIR/foo
-  Copying _build/install/default/lib/foo/foo.cmx to /OCAMLFIND_DESTDIR/foo/foo.cmx (executable: false)
-  Removing (if it exists) /OCAMLFIND_DESTDIR/foo/foo.cmxa
-  Installing /OCAMLFIND_DESTDIR/foo/foo.cmxa
-  Creating directory /OCAMLFIND_DESTDIR/foo
-  Copying _build/install/default/lib/foo/foo.cmxa to /OCAMLFIND_DESTDIR/foo/foo.cmxa (executable: false)
-  Removing (if it exists) /OCAMLFIND_DESTDIR/foo/foo.ml
-  Installing /OCAMLFIND_DESTDIR/foo/foo.ml
-  Creating directory /OCAMLFIND_DESTDIR/foo
-  Copying _build/install/default/lib/foo/foo.ml to /OCAMLFIND_DESTDIR/foo/foo.ml (executable: false)
-  Removing (if it exists) /OCAMLFIND_DESTDIR/foo/opam
-  Installing /OCAMLFIND_DESTDIR/foo/opam
-  Creating directory /OCAMLFIND_DESTDIR/foo
-  Copying _build/install/default/lib/foo/opam to /OCAMLFIND_DESTDIR/foo/opam (executable: false)
-  Removing (if it exists) /OCAMLFIND_DESTDIR/foo/foo.cmxs
-  Installing /OCAMLFIND_DESTDIR/foo/foo.cmxs
-  Creating directory /OCAMLFIND_DESTDIR/foo
-  Copying _build/install/default/lib/foo/foo.cmxs to /OCAMLFIND_DESTDIR/foo/foo.cmxs (executable: true)
+  Removing (if it exists) /OPAM_PREFIX/lib/foo/META
+  Installing /OPAM_PREFIX/lib/foo/META
+  Creating directory /OPAM_PREFIX/lib/foo
+  Copying _build/install/default/lib/foo/META to /OPAM_PREFIX/lib/foo/META (executable: false)
+  Removing (if it exists) /OPAM_PREFIX/lib/foo/dune-package
+  Installing /OPAM_PREFIX/lib/foo/dune-package
+  Creating directory /OPAM_PREFIX/lib/foo
+  Copying _build/install/default/lib/foo/dune-package to /OPAM_PREFIX/lib/foo/dune-package (executable: false)
+  Removing (if it exists) /OPAM_PREFIX/lib/foo/foo$ext_lib
+  Installing /OPAM_PREFIX/lib/foo/foo$ext_lib
+  Creating directory /OPAM_PREFIX/lib/foo
+  Copying _build/install/default/lib/foo/foo$ext_lib to /OPAM_PREFIX/lib/foo/foo$ext_lib (executable: false)
+  Removing (if it exists) /OPAM_PREFIX/lib/foo/foo.cma
+  Installing /OPAM_PREFIX/lib/foo/foo.cma
+  Creating directory /OPAM_PREFIX/lib/foo
+  Copying _build/install/default/lib/foo/foo.cma to /OPAM_PREFIX/lib/foo/foo.cma (executable: false)
+  Removing (if it exists) /OPAM_PREFIX/lib/foo/foo.cmi
+  Installing /OPAM_PREFIX/lib/foo/foo.cmi
+  Creating directory /OPAM_PREFIX/lib/foo
+  Copying _build/install/default/lib/foo/foo.cmi to /OPAM_PREFIX/lib/foo/foo.cmi (executable: false)
+  Removing (if it exists) /OPAM_PREFIX/lib/foo/foo.cmt
+  Installing /OPAM_PREFIX/lib/foo/foo.cmt
+  Creating directory /OPAM_PREFIX/lib/foo
+  Copying _build/install/default/lib/foo/foo.cmt to /OPAM_PREFIX/lib/foo/foo.cmt (executable: false)
+  Removing (if it exists) /OPAM_PREFIX/lib/foo/foo.cmx
+  Installing /OPAM_PREFIX/lib/foo/foo.cmx
+  Creating directory /OPAM_PREFIX/lib/foo
+  Copying _build/install/default/lib/foo/foo.cmx to /OPAM_PREFIX/lib/foo/foo.cmx (executable: false)
+  Removing (if it exists) /OPAM_PREFIX/lib/foo/foo.cmxa
+  Installing /OPAM_PREFIX/lib/foo/foo.cmxa
+  Creating directory /OPAM_PREFIX/lib/foo
+  Copying _build/install/default/lib/foo/foo.cmxa to /OPAM_PREFIX/lib/foo/foo.cmxa (executable: false)
+  Removing (if it exists) /OPAM_PREFIX/lib/foo/foo.ml
+  Installing /OPAM_PREFIX/lib/foo/foo.ml
+  Creating directory /OPAM_PREFIX/lib/foo
+  Copying _build/install/default/lib/foo/foo.ml to /OPAM_PREFIX/lib/foo/foo.ml (executable: false)
+  Removing (if it exists) /OPAM_PREFIX/lib/foo/opam
+  Installing /OPAM_PREFIX/lib/foo/opam
+  Creating directory /OPAM_PREFIX/lib/foo
+  Copying _build/install/default/lib/foo/opam to /OPAM_PREFIX/lib/foo/opam (executable: false)
+  Removing (if it exists) /OPAM_PREFIX/lib/foo/foo.cmxs
+  Installing /OPAM_PREFIX/lib/foo/foo.cmxs
+  Creating directory /OPAM_PREFIX/lib/foo
+  Copying _build/install/default/lib/foo/foo.cmxs to /OPAM_PREFIX/lib/foo/foo.cmxs (executable: true)
   Removing (if it exists) /OPAM_PREFIX/bin/exec
   Installing /OPAM_PREFIX/bin/exec
   Creating directory /OPAM_PREFIX/bin
@@ -151,26 +150,26 @@ destdir`:
   Installing /OPAM_PREFIX/man/man3/another-man-page.3
   Creating directory /OPAM_PREFIX/man/man3
   Copying _build/install/default/man/man3/another-man-page.3 to /OPAM_PREFIX/man/man3/another-man-page.3 (executable: false)
-  Removing (if it exists) /OCAMLFIND_DESTDIR/foo/META
-  Removing (if it exists) /OCAMLFIND_DESTDIR/foo/dune-package
-  Removing (if it exists) /OCAMLFIND_DESTDIR/foo/foo$ext_lib
-  Removing (if it exists) /OCAMLFIND_DESTDIR/foo/foo.cma
-  Removing (if it exists) /OCAMLFIND_DESTDIR/foo/foo.cmi
-  Removing (if it exists) /OCAMLFIND_DESTDIR/foo/foo.cmt
-  Removing (if it exists) /OCAMLFIND_DESTDIR/foo/foo.cmx
-  Removing (if it exists) /OCAMLFIND_DESTDIR/foo/foo.cmxa
-  Removing (if it exists) /OCAMLFIND_DESTDIR/foo/foo.ml
-  Removing (if it exists) /OCAMLFIND_DESTDIR/foo/opam
-  Removing (if it exists) /OCAMLFIND_DESTDIR/foo/foo.cmxs
+  Removing (if it exists) /OPAM_PREFIX/lib/foo/META
+  Removing (if it exists) /OPAM_PREFIX/lib/foo/dune-package
+  Removing (if it exists) /OPAM_PREFIX/lib/foo/foo$ext_lib
+  Removing (if it exists) /OPAM_PREFIX/lib/foo/foo.cma
+  Removing (if it exists) /OPAM_PREFIX/lib/foo/foo.cmi
+  Removing (if it exists) /OPAM_PREFIX/lib/foo/foo.cmt
+  Removing (if it exists) /OPAM_PREFIX/lib/foo/foo.cmx
+  Removing (if it exists) /OPAM_PREFIX/lib/foo/foo.cmxa
+  Removing (if it exists) /OPAM_PREFIX/lib/foo/foo.ml
+  Removing (if it exists) /OPAM_PREFIX/lib/foo/opam
+  Removing (if it exists) /OPAM_PREFIX/lib/foo/foo.cmxs
   Removing (if it exists) /OPAM_PREFIX/bin/exec
   Removing (if it exists) /OPAM_PREFIX/man/a-man-page-with-no-ext
   Removing (if it exists) /OPAM_PREFIX/man/man1/a-man-page.1
   Removing (if it exists) /OPAM_PREFIX/man/man3/another-man-page.3
   Removing directory (if empty) /OPAM_PREFIX/man/man3
   Removing directory (if empty) /OPAM_PREFIX/man/man1
   Removing directory (if empty) /OPAM_PREFIX/man
+  Removing directory (if empty) /OPAM_PREFIX/lib/foo
   Removing directory (if empty) /OPAM_PREFIX/bin
-  Removing directory (if empty) /OCAMLFIND_DESTDIR/foo
 
 If only libdir is passed, binaries are installed under prefix/bin and libraries
 in libdir: