Allow to configure link_flags in env

Signed-off-by: Hugo Heuzard <[email protected]>

CHANGES.md

@@ -298,6 +298,8 @@ Unreleased
 - Delete old `promote-into`, `promote-until-clean` and `promote-until-clean-into`
   syntax (#5091, Andrey Mokhov).
 
+- Add link_flags in the env stanza (#5215)
+
 2.9.2 (unreleased)
 ------------------
 

doc/dune-files.rst

@@ -1540,6 +1540,9 @@ Fields supported in ``<settings>`` are:
 
 - any OCaml flags field. See :ref:`ocaml-flags` for more details.
 
+- ``(link_flags <flags>)`` to specify flags to ocaml when linking an
+  executable. See :ref:`executables stanza <shared-exe-fields>`.
+
 - ``(c_flags <flags>)`` and ``(cxx_flags <flags>)``
   to specify compilation flags for C and C++ stubs, respectively.
   See `library`_ for more details.

src/dune_rules/dune_env.ml

@@ -15,6 +15,13 @@ module Stanza = struct
     and+ cxx = Ordered_set_lang.Unexpanded.field "cxx_flags" ?check in
     Foreign_language.Dict.make ~c ~cxx
 
+  let link_flags ~since =
+    let check =
+      Option.map since ~f:(fun since ->
+          Dune_lang.Syntax.since Stanza.syntax since)
+    in
+    Ordered_set_lang.Unexpanded.field "link_flags" ?check
+
   let menhir_flags ~since =
     let check =
       Option.map since ~f:(fun since ->
@@ -74,6 +81,7 @@ module Stanza = struct
   type config =
     { flags : Ocaml_flags.Spec.t
     ; foreign_flags : Ordered_set_lang.Unexpanded.t Foreign_language.Dict.t
+    ; link_flags : Ordered_set_lang.Unexpanded.t
     ; env_vars : Env.t
     ; binaries : File_binding.Unexpanded.t list
     ; inline_tests : Inline_tests.t option
@@ -87,6 +95,7 @@ module Stanza = struct
   let equal_config
       { flags
       ; foreign_flags
+      ; link_flags
       ; env_vars
       ; binaries
       ; inline_tests
@@ -99,6 +108,7 @@ module Stanza = struct
     Ocaml_flags.Spec.equal flags t.flags
     && Foreign_language.Dict.equal Ordered_set_lang.Unexpanded.equal
          foreign_flags t.foreign_flags
+    && Ordered_set_lang.Unexpanded.equal link_flags t.link_flags
     && Env.equal env_vars t.env_vars
     && List.equal File_binding.Unexpanded.equal binaries t.binaries
     && Option.equal Inline_tests.equal inline_tests t.inline_tests
@@ -114,6 +124,7 @@ module Stanza = struct
     { flags = Ocaml_flags.Spec.standard
     ; foreign_flags =
         Foreign_language.Dict.make_both Ordered_set_lang.Unexpanded.standard
+    ; link_flags = Ordered_set_lang.Unexpanded.standard
     ; env_vars = Env.empty
     ; binaries = []
     ; inline_tests = None
@@ -181,6 +192,7 @@ module Stanza = struct
   let config =
     let+ flags = Ocaml_flags.Spec.decode
     and+ foreign_flags = foreign_flags ~since:(Some (1, 7))
+    and+ link_flags = link_flags ~since:(Some (3, 0))
     and+ env_vars = env_vars_field
     and+ binaries =
       field ~default:[] "binaries"
@@ -194,6 +206,7 @@ module Stanza = struct
     and+ format_config = Format_config.field ~since:(2, 8) in
     { flags
     ; foreign_flags
+    ; link_flags
     ; env_vars
     ; binaries
     ; inline_tests

src/dune_rules/dune_env.mli

@@ -28,6 +28,7 @@ module Stanza : sig
   type config =
     { flags : Ocaml_flags.Spec.t
     ; foreign_flags : Ordered_set_lang.Unexpanded.t Foreign_language.Dict.t
+    ; link_flags : Ordered_set_lang.Unexpanded.t
     ; env_vars : Env.t
     ; binaries : File_binding.Unexpanded.t list
     ; inline_tests : Inline_tests.t option

src/dune_rules/env_node.ml

@@ -18,6 +18,7 @@ type t =
   ; local_binaries : File_binding.Expanded.t list Memo.Lazy.t
   ; ocaml_flags : Ocaml_flags.t Memo.Lazy.t
   ; foreign_flags : string list Action_builder.t Foreign_language.Dict.t
+  ; link_flags : string list Action_builder.t Memo.Lazy.t
   ; external_env : Env.t Memo.Lazy.t
   ; bin_artifacts : Artifacts.Bin.t Memo.Lazy.t
   ; inline_tests : Dune_env.Stanza.Inline_tests.t Memo.Lazy.t
@@ -36,6 +37,9 @@ let ocaml_flags t = Memo.Lazy.force t.ocaml_flags
 
 let foreign_flags t = t.foreign_flags
 
+let link_flags t =
+  Memo.Lazy.force t.link_flags |> Action_builder.memo_build_join
+
 let external_env t = Memo.Lazy.force t.external_env
 
 let bin_artifacts t = Memo.Lazy.force t.bin_artifacts
@@ -167,6 +171,15 @@ let make ~dir ~inherit_from ~scope ~config_stanza ~profile ~expander
   let foreign_flags =
     Foreign_language.Dict.make ~c:(foreign_flags C) ~cxx:(foreign_flags Cxx)
   in
+  let link_flags =
+    inherited
+      ~field:(fun t -> Memo.Build.return (link_flags t))
+      ~root:(Action_builder.return [])
+      (fun flags ->
+        let+ expander = Memo.Lazy.force expander in
+        let expander = Expander.set_dir expander ~dir in
+        Expander.expand_and_eval_set expander config.link_flags ~standard:flags)
+  in
   let menhir_flags =
     inherited
       ~field:(fun t -> Memo.Build.return (menhir_flags t))
@@ -208,6 +221,7 @@ let make ~dir ~inherit_from ~scope ~config_stanza ~profile ~expander
   { scope
   ; ocaml_flags
   ; foreign_flags
+  ; link_flags
   ; external_env
   ; bin_artifacts
   ; local_binaries

src/dune_rules/env_node.mli

@@ -43,6 +43,8 @@ val js_of_ocaml :
 
 val foreign_flags : t -> string list Action_builder.t Foreign_language.Dict.t
 
+val link_flags : t -> string list Action_builder.t
+
 val local_binaries : t -> File_binding.Expanded.t list Memo.Build.t
 
 val bin_artifacts : t -> Artifacts.Bin.t Memo.Build.t

src/dune_rules/exe_rules.ml

@@ -173,18 +173,15 @@ let executables_rules ~sctx ~dir ~expander ~dir_contents ~scope ~compile_info
        files directly to improve perf. *)
     let link_deps, sandbox = Dep_conf_eval.unnamed ~expander exes.link_deps in
     let link_args =
-      let standard =
+      let use_standard_cxx_flags =
         match Dune_project.use_standard_c_and_cxx_flags project with
-        | Some true when Buildable.has_foreign_cxx exes.buildable ->
-          let open Action_builder.O in
-          let+ flags = Cxx_flags.get_flags ~for_:Link ctx in
-          List.concat_map flags ~f:(fun f -> [ "-cclib"; f ])
-        | _ -> Action_builder.return []
+        | Some true -> Buildable.has_foreign_cxx exes.buildable
+        | _ -> false
       in
       let open Action_builder.O in
       let link_flags =
         link_deps
-        >>> Expander.expand_and_eval_set expander exes.link_flags ~standard
+        >>> Super_context.link_flags sctx ~dir ~expander ~use_standard_cxx_flags ~flags:exes.link_flags
       in
       let+ flags = link_flags
       and+ ctypes_cclib_flags =

src/dune_rules/super_context.ml

@@ -402,6 +402,23 @@ let foreign_flags t ~dir ~expander ~flags ~language =
   in
   Action_builder.memoize (sprintf "%s flags" name) flags
 
+let link_flags t ~dir ~expander ~use_standard_cxx_flags ~flags =
+  let env_tree = t.env_tree in
+  let default =
+    get_node env_tree ~dir >>| Env_node.link_flags |> Action_builder.memo_build_join
+  in
+  let default =
+    if use_standard_cxx_flags
+    then 
+      let open Action_builder.O in
+      let+ default = default
+      and+ flags = Cxx_flags.get_flags ~for_:Link (context t) in
+      default @ List.concat_map flags ~f:(fun f -> [ "-cclib"; f ])
+    else default 
+  in
+  Action_builder.memoize "link flags"
+    (Expander.expand_and_eval_set expander flags ~standard:default)
+
 let menhir_flags t ~dir ~expander ~flags =
   let t = t.env_tree in
   let default =
@@ -422,6 +439,7 @@ let dump_env t ~dir =
   let t = t.env_tree in
   let ocaml_flags = get_node t ~dir >>= Env_node.ocaml_flags in
   let foreign_flags = get_node t ~dir >>| Env_node.foreign_flags in
+  let link_flags = get_node t ~dir >>| Env_node.link_flags in
   let menhir_flags = get_node t ~dir >>| Env_node.menhir_flags in
   let coq_flags = get_node t ~dir >>= Env_node.coq in
   let js_of_ocaml = get_node t ~dir >>= Env_node.js_of_ocaml in
@@ -436,6 +454,10 @@ let dump_env t ~dir =
     List.map
       ~f:Dune_lang.Encoder.(pair string (list string))
       [ ("c_flags", c_flags); ("cxx_flags", cxx_flags) ]
+  and+ link_flags_dump =
+    let+ flags = Action_builder.memo_build_join link_flags in
+    [ ("link_flags", flags) ]
+    |> List.map ~f:Dune_lang.Encoder.(pair string (list string))
   and+ menhir_dump =
     let+ flags = Action_builder.memo_build_join menhir_flags in
     [ ("menhir_flags", flags) ]
@@ -448,7 +470,8 @@ let dump_env t ~dir =
     let* jsoo = Action_builder.memo_build js_of_ocaml in
     Js_of_ocaml.Flags.dump jsoo.flags
   in
-  List.concat [ o_dump; c_dump; menhir_dump; coq_dump; jsoo_dump ]
+  List.concat
+    [ o_dump; c_dump; link_flags_dump; menhir_dump; coq_dump; jsoo_dump ]
 
 let resolve_program t ~dir ?hint ~loc bin =
   let t = t.env_tree in

src/dune_rules/super_context.mli

@@ -86,6 +86,14 @@ val foreign_flags :
   -> language:Foreign_language.t
   -> string list Action_builder.t
 
+val link_flags :
+     t
+  -> dir:Path.Build.t
+  -> expander:Expander.t
+  -> use_standard_cxx_flags:bool
+  -> flags:Ordered_set_lang.Unexpanded.t
+  -> string list Action_builder.t
+
 val menhir_flags :
      t
   -> dir:Path.Build.t

test/blackbox-tests/test-cases/env/env-link_flags.t/a.ml

@@ -0,0 +1 @@
+let () = print_endline "'A' was linked"

test/blackbox-tests/test-cases/env/env-link_flags.t/main.ml

@@ -0,0 +1,4 @@
+let () = print_endline "Starting main"
+
+let _ = `no_reference_to_A
+

test/blackbox-tests/test-cases/env/env-link_flags.t/run.t

@@ -0,0 +1,16 @@
+  $ cat >> dune-project <<EOF
+  > (lang dune 3.0)
+  > EOF
+
+  $ cat >> dune << EOF
+  > (library (name a)(modules a))
+  > (executable (name main) (modules main) (libraries a))
+  > (env (linkall-profile (link_flags (:standard -linkall))))
+  > EOF
+
+  $ dune exec ./main.exe
+  Starting main
+
+  $ dune exec ./main.exe --profile linkall-profile
+  'A' was linked
+  Starting main

test/blackbox-tests/test-cases/workspaces.t/run.t

@@ -48,6 +48,7 @@ Workspaces also allow you to set the env for a context:
   (ocamlopt_flags (-g))
   (c_flags ())
   (cxx_flags ())
+  (link_flags ())
   (menhir_flags ())
   (coq_flags (-q))
   (js_of_ocaml_flags ())