Fix link of packed module with separate compilation

CHANGES.md

@@ -12,6 +12,7 @@
 ## Bug fixes
 * Runtime: fix parsing of unsigned integers (0u2147483648)
 * Toplevel: fix missing primitives with separate compilation
+* Compiler: fix link of packed modules with separate compilation
 
 # 5.8.2 (2024-05-26) - Luc
 

compiler/lib/ocaml_compiler.ml

@@ -247,6 +247,21 @@ module Cmo_format = struct
   let requires (t : t) = List.map t.cu_required_compunits ~f:(fun (Compunit u) -> u)
   [@@if ocaml_version >= (5, 2, 0)]
 
+  let provides (t : t) =
+    List.filter_map t.cu_reloc ~f:(fun ((reloc : Cmo_format.reloc_info), _) ->
+        match reloc with
+        | Reloc_setglobal i -> Some (Ident.name i)
+        | Reloc_getglobal _ | Reloc_literal _ | Reloc_primitive _ -> None)
+  [@@if ocaml_version < (5, 2, 0)]
+
+  let provides (t : t) =
+    List.filter_map t.cu_reloc ~f:(fun ((reloc : Cmo_format.reloc_info), _) ->
+        match reloc with
+        | Reloc_setcompunit (Compunit u) -> Some u
+        | Reloc_getcompunit _ | Reloc_getpredef _ | Reloc_literal _ | Reloc_primitive _ ->
+            None)
+  [@@if ocaml_version >= (5, 2, 0)]
+
   let primitives (t : t) = t.cu_primitives
 
   let imports (t : t) = t.cu_imports

compiler/lib/ocaml_compiler.mli

@@ -61,6 +61,8 @@ module Cmo_format : sig
 
   val requires : t -> string list
 
+  val provides : t -> string list
+
   val primitives : t -> string list
 
   val force_link : t -> bool

compiler/lib/unit_info.ml

@@ -48,7 +48,8 @@ let of_primitives l =
 
 let of_cmo (cmo : Cmo_format.compilation_unit) =
   let open Ocaml_compiler in
-  let provides = StringSet.singleton (Cmo_format.name cmo) in
+  (* A packed librariy register global for packed modules. *)
+  let provides = StringSet.of_list (Cmo_format.name cmo :: Cmo_format.provides cmo) in
   let requires = StringSet.of_list (Cmo_format.requires cmo) in
   let requires = StringSet.diff requires provides in
   let effects_without_cps =

compiler/tests-linkall/dune

@@ -0,0 +1,29 @@
+;; Test that separate compilation behave correctly in presence of pack
+
+(env
+ (_
+  (js_of_ocaml
+   (compilation_mode separate))))
+
+(executable
+ (name test)
+ (modes byte js)
+ (libraries dynlink)
+ ;; It doesn't seem possible to create a pack-ed module with dune.
+ ;; However, dynlink uses pack to embed a copy
+ ;; of the compiler up until OCaml 5.2.
+ ;; Let's use it for the test
+ (link_flags
+  (:standard -linkall)))
+
+(rule
+ (target test.output)
+ (action
+  (with-stdout-to
+   %{target}
+   (run node %{dep:test.bc.js}))))
+
+(rule
+ (alias runtest)
+ (action
+  (diff test.reference test.output)))

compiler/tests-linkall/test.ml

@@ -0,0 +1 @@
+print_endline "hello world"

compiler/tests-linkall/test.reference

@@ -0,0 +1 @@
+hello world