Never pass -nodynlink option

This is an optimization when PIC executables are not used, but this
optimization is disabled becauses it causes errors on arm32. Most
distributions are going in the direction of requiring PIC, and
`-nodynlink` might go away (see ocaml/ocaml#8867), so the supporting
code in dune (which is bypassed in most cases) can be removed.

Closes #4069
Closes #2527

Signed-off-by: Etienne Millon <me@emillon.org>

CHANGES.md

@@ -111,6 +111,10 @@ Unreleased
 - Fix `libexec` and `libexec-private` variables. In cross-compilation settings,
   they now point to the file in the host context. (#4058, fixes #4057, @TheLortex)
 
+- Remove support for passing `-nodynlink` for executables. It was bypassed in
+  most cases and not correct in other cases in particular on arm32.
+  (#4085, fixes #4069, fixes #2527, @emillon)
+
 2.7.1 (2/09/2020)
 -----------------
 

src/dune_rules/cinaps.ml

@@ -101,7 +101,7 @@ let gen_rules sctx t ~dir ~scope =
       ~requires_compile:(Lib.Compile.direct_requires compile_info)
       ~requires_link:(Lib.Compile.requires_link compile_info)
       ~flags:(Ocaml_flags.of_list [ "-w"; "-24" ])
-      ~js_of_ocaml:None ~dynlink:false ~package:None
+      ~js_of_ocaml:None ~package:None
   in
   Exe.build_and_link cctx
     ~program:{ name; main_module_name; loc }

src/dune_rules/compilation_context.ml

@@ -66,7 +66,6 @@ type t =
   ; opaque : bool
   ; stdlib : Ocaml_stdlib.t option
   ; js_of_ocaml : Dune_file.Js_of_ocaml.t option
-  ; dynlink : bool
   ; sandbox : Sandbox_config.t
   ; package : Package.t option
   ; vimpl : Vimpl.t option
@@ -102,8 +101,6 @@ let stdlib t = t.stdlib
 
 let js_of_ocaml t = t.js_of_ocaml
 
-let dynlink t = t.dynlink
-
 let sandbox t = t.sandbox
 
 let package t = t.package
@@ -118,8 +115,7 @@ let context t = Super_context.context t.super_context
 
 let create ~super_context ~scope ~expander ~obj_dir ~modules ~flags
     ~requires_compile ~requires_link ?(preprocessing = Pp_spec.dummy) ~opaque
-    ?stdlib ~js_of_ocaml ~dynlink ~package ?vimpl ?modes ?(bin_annot = true) ()
-    =
+    ?stdlib ~js_of_ocaml ~package ?vimpl ?modes ?(bin_annot = true) () =
   let project = Scope.project scope in
   let requires_compile =
     if Dune_project.implicit_transitive_deps project then
@@ -154,7 +150,6 @@ let create ~super_context ~scope ~expander ~obj_dir ~modules ~flags
   ; opaque
   ; stdlib
   ; js_of_ocaml
-  ; dynlink
   ; sandbox
   ; package
   ; vimpl

src/dune_rules/compilation_context.mli

@@ -39,7 +39,6 @@ val create :
   -> opaque:opaque
   -> ?stdlib:Ocaml_stdlib.t
   -> js_of_ocaml:Dune_file.Js_of_ocaml.t option
-  -> dynlink:bool
   -> package:Package.t option
   -> ?vimpl:Vimpl.t
   -> ?modes:Dune_file.Mode_conf.Set.Details.t Mode.Dict.t
@@ -82,8 +81,6 @@ val stdlib : t -> Ocaml_stdlib.t option
 
 val js_of_ocaml : t -> Dune_file.Js_of_ocaml.t option
 
-val dynlink : t -> bool
-
 val sandbox : t -> Sandbox_config.t
 
 val package : t -> Package.t option

src/dune_rules/exe_rules.ml

@@ -129,18 +129,9 @@ let executables_rules ~sctx ~dir ~expander ~dir_contents ~scope ~compile_info
       else
         Some js_of_ocaml
     in
-    let dynlink =
-      (* See https://github.com/ocaml/dune/issues/2527 *)
-      true
-      || Dune_file.Executables.Link_mode.Map.existsi exes.modes
-           ~f:(fun mode _loc ->
-             match mode with
-             | Other { kind = Shared_object; _ } -> true
-             | _ -> false)
-    in
     Compilation_context.create () ~super_context:sctx ~expander ~scope ~obj_dir
       ~modules ~flags ~requires_link ~requires_compile ~preprocessing:pp
-      ~js_of_ocaml ~opaque:Inherit_from_settings ~dynlink ~package:exes.package
+      ~js_of_ocaml ~opaque:Inherit_from_settings ~package:exes.package
   in
   let requires_compile = Compilation_context.requires_compile cctx in
   let preprocess =

src/dune_rules/inline_tests.ml

@@ -292,8 +292,7 @@ include Sub_system.Register_end_point (struct
       Compilation_context.create () ~super_context:sctx ~expander ~scope
         ~obj_dir ~modules ~opaque:(Explicit false) ~requires_compile:runner_libs
         ~requires_link:(lazy runner_libs)
-        ~flags ~js_of_ocaml:(Some lib.buildable.js_of_ocaml) ~dynlink:false
-        ~package
+        ~flags ~js_of_ocaml:(Some lib.buildable.js_of_ocaml) ~package
     in
     let linkages =
       let modes =

src/dune_rules/lib_rules.ml

@@ -364,9 +364,6 @@ let cctx (lib : Library.t) ~sctx ~source_modules ~dir ~expander ~scope
   let modules = Vimpl.impl_modules vimpl modules in
   let requires_compile = Lib.Compile.direct_requires compile_info in
   let requires_link = Lib.Compile.requires_link compile_info in
-  let dynlink =
-    Dynlink_supported.get lib.dynlink ctx.supports_shared_libraries
-  in
   let modes =
     let { Lib_config.has_native; _ } = ctx.lib_config in
     Dune_file.Mode_conf.Set.eval_detailed lib.modes ~has_native
@@ -375,7 +372,7 @@ let cctx (lib : Library.t) ~sctx ~source_modules ~dir ~expander ~scope
   Compilation_context.create () ~super_context:sctx ~expander ~scope ~obj_dir
     ~modules ~flags ~requires_compile ~requires_link ~preprocessing:pp
     ~opaque:Inherit_from_settings ~js_of_ocaml:(Some lib.buildable.js_of_ocaml)
-    ~dynlink ?stdlib:lib.stdlib ~package ?vimpl ~modes
+    ?stdlib:lib.stdlib ~package ?vimpl ~modes
 
 let library_rules (lib : Library.t) ~cctx ~source_modules ~dir_contents
     ~compile_info =

src/dune_rules/module_compilation.ml

@@ -54,7 +54,6 @@ let build_cm cctx ~dep_graphs ~precompiled_cmi ~cm_kind (m : Module.t) ~phase =
   let ctx = SC.context sctx in
   let stdlib = CC.stdlib cctx in
   let mode = Mode.of_cm_kind cm_kind in
-  let dynlink = CC.dynlink cctx in
   let sandbox =
     let default = CC.sandbox cctx in
     match Module.kind m with
@@ -187,10 +186,6 @@ let build_cm cctx ~dep_graphs ~precompiled_cmi ~cm_kind (m : Module.t) ~phase =
           ; Command.Args.S obj_dirs
           ; Cm_kind.Dict.get (CC.includes cctx) cm_kind
           ; As extra_args
-          ; ( if dynlink || cm_kind <> Cmx then
-              Command.Args.empty
-            else
-              A "-nodynlink" )
           ; A "-no-alias-deps"
           ; opaque_arg
           ; As (Fdo.phase_flags phase)

src/dune_rules/preprocessing.ml

@@ -345,7 +345,7 @@ let build_ppx_driver sctx ~scope ~target ~pps ~pp_names =
     let modules = Modules.singleton_exe module_ in
     Compilation_context.create ~super_context:sctx ~scope ~expander ~obj_dir
       ~modules ~flags ~requires_compile ~requires_link ~opaque ~js_of_ocaml:None
-      ~dynlink:false ~package:None ~bin_annot:false ()
+      ~package:None ~bin_annot:false ()
   in
   Exe.build_and_link ~program ~linkages cctx ~promote:None
 

src/dune_rules/toplevel.ml

@@ -180,7 +180,7 @@ module Stanza = struct
         ~expander
         ~modules:(Source.modules source preprocessing)
         ~opaque:(Explicit false) ~requires_compile ~requires_link ~flags
-        ~js_of_ocaml:None ~dynlink:false ~package:None ~preprocessing
+        ~js_of_ocaml:None ~package:None ~preprocessing
     in
     let resolved = make ~cctx ~source ~preprocess:toplevel.pps in
     setup_rules resolved

src/dune_rules/utop.ml

@@ -109,8 +109,8 @@ let setup sctx ~dir =
     Compilation_context.create () ~super_context:sctx ~expander ~scope ~obj_dir
       ~modules ~opaque:(Explicit false)
       ~requires_link:(lazy requires)
-      ~requires_compile:requires ~flags ~js_of_ocaml:None ~dynlink:false
-      ~package:None ~preprocessing
+      ~requires_compile:requires ~flags ~js_of_ocaml:None ~package:None
+      ~preprocessing
   in
   let toplevel = Toplevel.make ~cctx ~source ~preprocess:pps in
   Toplevel.setup_rules toplevel