Ctypes: adds a stop-gap measure deps fields

doc/dune-files.rst

@@ -400,7 +400,8 @@ adding the following field to the ``dune-project`` file:
 
 In this mode, Dune will populate the ``:standard`` set of C flags with the
 content of ``ocamlc_cflags`` and  ``ocamlc_cppflags``. These flags can be
-completed or overridden using the :ref:`ordered-set-language`.
+completed or overridden using the :ref:`ordered-set-language`. The value
+``true`` is the default for Dune 3.0.
 
 accept_alternative_dune_file_name
 ---------------------------------

doc/foreign-code.rst

@@ -257,6 +257,11 @@ descriptions by referencing them as the module specified in optional
    - ``(headers (preamble <preamble>)`` adds directly the preamble. Variables
      can be used in ``<preamble>`` such as ``%{read: }``.
 
+- Since the Dune's ``ctypes`` feature is still experimental, it could be useful to
+  add additional dependencies in order to make sure that local
+  headers or libraries are available: ``(deps <deps-conf list>)``. See the
+  :ref:`deps-field` section for more details.
+
 ``<optional-function-description-fields>`` are:
 
 - ``(concurrency <sequential|unlocked|lwt_jobs|lwt_preemptive>)`` tells ``ctypes
@@ -270,7 +275,9 @@ descriptions by referencing them as the module specified in optional
 - ``(vendored (c_flags <flags>) (c_library_flags <flags>))`` provide the build
   and link flags for binding your vendored code. You must also provide
   instructions in your ``dune`` file on how to build the vendored foreign
-  library; see the :ref:`foreign_library` stanza.
+  library; see the :ref:`foreign_library` stanza. Usually the ``<flags>`` should
+  contain ``:standard`` in order to add the default flags used by the OCaml
+  compiler for C files :ref:`always-add-cflags`.
 
 
 .. _foreign-sandboxing:
@@ -292,6 +299,12 @@ To do that, follow the following procedure:
 
   - depends on this directory recursively via :ref:`source_tree <source_tree>`
   - invokes the external build system
+  - copies the generated files
+  - the C archive ``.a`` must be built with ``-fpic``
+  - the ``libfoo.so`` must be copied as ``dllfoo.so``, and no ``libfoo.so``
+    should appear, otherwise the dynamic linking of the C library will be
+    attempted. However, this usually fails because the ``libfoo.so`` isn't available at
+    the time of the execution.
 - *Attach* the C archive files to an OCaml library via :ref:`foreign-archives`.
 
 For instance, let's assume that you want to build a C library

src/dune_rules/ctypes_rules.ml

@@ -335,8 +335,7 @@ let rule ?(deps = []) ?stdout_to ?(args = []) ?(targets = []) ~exe ~sctx ~dir ()
   in
   Super_context.add_rule sctx ~dir build
 
-let build_c_program ~foreign_archives_deps ~sctx ~dir ~source_files ~scope
-    ~cflags_sexp ~output () =
+let build_c_program ~foreign_archives_deps ~sctx ~dir ~source_files ~scope ~cflags_sexp ~output ~deps () =
   let ctx = Super_context.context sctx in
   let open Memo.Build.O in
   let* exe =
@@ -364,11 +363,15 @@ let build_c_program ~foreign_archives_deps ~sctx ~dir ~source_files ~scope
     let source_file_deps =
       List.map source_files ~f:(Path.relative (Path.build dir))
       |> Dep.Set.of_files
+
     in
     let foreign_archives_deps =
       List.map foreign_archives_deps ~f:Path.build |> Dep.Set.of_files
     in
-    Dep.Set.union source_file_deps foreign_archives_deps
+    let open Action_builder.O in
+    let* () = Dep.Set.union source_file_deps foreign_archives_deps
+    |> Action_builder.deps in
+    deps
   in
   let build =
     let cflags_args =
@@ -402,7 +405,7 @@ let build_c_program ~foreign_archives_deps ~sctx ~dir ~source_files ~scope
     let action =
       let open Action_builder.O in
       let* include_args = Resolve.Build.read include_args in
-      Action_builder.deps deps
+      deps
       >>> Action_builder.map cflags_args ~f:(fun cflags_args ->
               let source_files = List.map source_files ~f:absolute_path_hack in
               let output = absolute_path_hack output in
@@ -445,7 +448,7 @@ let program_of_module_and_dir ~dir program =
     ; loc = Loc.in_file (Path.relative build_dir program)
     }
 
-let exe_build_and_link ?libraries ?(modules = []) ~scope ~loc ~dir ~cctx program
+let exe_build_and_link ?libraries ?(modules = []) ~scope ~loc ~dir ~cctx ~sandbox program
     =
   let open Memo.Build.O in
   let* cctx =
@@ -454,27 +457,31 @@ let exe_build_and_link ?libraries ?(modules = []) ~scope ~loc ~dir ~cctx program
   in
   let program = program_of_module_and_dir ~dir program in
   Exe.build_and_link ~program ~linkages:[ Exe.Linkage.native ] ~promote:None
+~sandbox
     cctx
 
-let exe_link_only ~dir ~shared_cctx program =
+let exe_link_only ~dir ~shared_cctx ~sandbox program ~deps =
+  let link_args =
+    let open Action_builder.O in
+    let+ () = deps in
+    Command.Args.empty
+  in
   let program = program_of_module_and_dir ~dir program in
-  Exe.link_many ~programs:[ program ] ~linkages:[ Exe.Linkage.native ]
-    ~promote:None shared_cctx
+  Exe.link_many ~link_args ~programs:[ program ] ~linkages:[ Exe.Linkage.native ]
+    ~promote:None shared_cctx ~sandbox
 
-let write_osl_to_sexp_file ~sctx ~dir ~filename osl =
+let write_osl_to_sexp_file ~sctx ~dir ~filename ~expand_flag flags =
   let build =
-    let path = Path.Build.relative dir filename in
-    let sexp =
-      let encoded =
-        match Ordered_set_lang.Unexpanded.encode osl with
-        | [ s ] -> s
-        | _lst ->
-          User_error.raise
-            [ Pp.textf "expected %s to contain a list of atoms" filename ]
-      in
-      Dune_lang.to_string encoded
+   let sexp =
+      let open Action_builder.O in
+       let* expander =
+         Action_builder.memo_build @@ Super_context.expander sctx ~dir in
+       let+ flags = expand_flag ~expander flags in
+       let sexp = Sexp.List (List.map ~f:(fun x -> Sexp.Atom x) flags) in
+       Sexp.to_string sexp
     in
-    Action_builder.write_file path sexp
+    let path = Path.Build.relative dir filename in
+    Action_builder.write_file_dyn path sexp
   in
   Super_context.add_rule ~loc:Loc.none sctx ~dir build
 
@@ -506,6 +513,8 @@ let gen_rules ~cctx ~buildable ~loc ~scope ~dir ~sctx =
         ; Foreign.Archive.dll_file ~archive ~dir ~ext_dll
         ])
   in
+  let* expander = Super_context.expander sctx ~dir in
+  let deps, sandbox = Dep_conf_eval.unnamed ~expander ctypes.deps in
   let* () =
     write_c_types_includer_module ~sctx ~dir
       ~filename:(ml_of_module_name c_types_includer_module)
@@ -525,9 +534,14 @@ let gen_rules ~cctx ~buildable ~loc ~scope ~dir ~sctx =
     | Vendored { c_flags; c_library_flags } ->
       let* () =
         write_osl_to_sexp_file ~sctx ~dir ~filename:cflags_sexp c_flags
+          ~expand_flag:(fun ~expander flags -> Super_context.foreign_flags
+              sctx ~dir ~expander ~flags ~language:C)
       in
       write_osl_to_sexp_file ~sctx ~dir ~filename:c_library_flags_sexp
         c_library_flags
+          ~expand_flag:(fun ~expander flags ->
+                    Expander.expand_and_eval_set expander flags
+                          ~standard:(Action_builder.return []))
     | Pkg_config ->
       let cflags_sexp = Stanza_util.cflags_sexp ctypes in
       let discover_script = Stanza_util.discover_script ctypes in
@@ -536,7 +550,7 @@ let gen_rules ~cctx ~buildable ~loc ~scope ~dir ~sctx =
           ~cflags_sexp ~c_library_flags_sexp ~external_library_name
       in
       let* () =
-        exe_build_and_link ~scope ~loc ~dir ~cctx
+        exe_build_and_link ~scope ~loc ~dir ~cctx ~sandbox
           ~libraries:[ "dune.configurator" ] discover_script
       in
       rule
@@ -545,7 +559,7 @@ let gen_rules ~cctx ~buildable ~loc ~scope ~dir ~sctx =
   in
   let generated_entry_module = Stanza_util.entry_module ctypes in
   let headers = ctypes.Ctypes.headers in
-  let exe_link_only = exe_link_only ~dir ~shared_cctx:cctx in
+  let exe_link_only = exe_link_only ~deps ~dir ~shared_cctx:cctx  ~sandbox in
   (* Type_gen produces a .c file, taking your type description module above as
      an input. The .c file is compiled into an .exe. The .exe, when run produces
      an .ml file. The .ml file is compiled into a module that will have the
@@ -573,7 +587,7 @@ let gen_rules ~cctx ~buildable ~loc ~scope ~dir ~sctx =
     let* () =
       build_c_program ~foreign_archives_deps ~sctx ~dir ~scope ~cflags_sexp
         ~source_files:[ c_generated_types_cout_c ]
-        ~output:c_generated_types_cout_exe ()
+        ~output:c_generated_types_cout_exe ~deps ()
     in
     rule
       ~stdout_to:(c_generated_types_module |> ml_of_module_name)

src/dune_rules/ctypes_stanza.ml

@@ -111,6 +111,7 @@ type t =
   ; function_description : Function_description.t list
   ; generated_types : Module_name.t
   ; generated_entry_point : Module_name.t
+  ; deps : Dep_conf.t list
   }
 
 let name = "ctypes"
@@ -134,6 +135,8 @@ let decode =
      and+ generated_types = field_o "generated_types" Module_name.decode
      and+ generated_entry_point =
        field "generated_entry_point" Module_name.decode
+     and+ deps =
+       field_o "deps" (repeat Dep_conf.decode)
      in
      { external_library_name
      ; build_flags_resolver =
@@ -145,6 +148,7 @@ let decode =
          Option.value generated_types
            ~default:(Module_name.of_string "Types_generated")
      ; generated_entry_point
+     ; deps = Option.value ~default:[] deps
      })
 
 let () =

src/dune_rules/ctypes_stanza.mli

@@ -51,6 +51,7 @@ type t =
   ; function_description : Function_description.t list
   ; generated_types : Module_name.t
   ; generated_entry_point : Module_name.t
+  ; deps : Dep_conf.t list
   }
 
 type Stanza.t += T of t