Hi,
I obtain an error `Reference to undefined global ...' with ocamlbuild in
the following situation (simplified example, attached as example.diff).
[File] [Contents]
example
|-- Main.ml let _ = Pack.Packed.g ()
|
|-- Pack.mlpack pack/Packed
|
|-- _tags <lib>: include
| <pack/*.cmx>: for-pack(Pack)
|
|-- lib
| |-- Lib.ml let f () = ()
| `-- Lib.mli val f : unit -> unit
`-- pack
`-- Packed.ml let g () = Lib.f ()
$ ocamlbuild -classic-display Main.byte
/usr/pkg/bin/ocamldep.opt -modules Main.ml > Main.ml.depends
/usr/pkg/bin/ocamldep.opt -modules pack/Packed.ml > pack/Packed.ml.depends
/usr/pkg/bin/ocamldep.opt -modules lib/Lib.mli > lib/Lib.mli.depends
/usr/pkg/bin/ocamlc.opt -c -I lib -o lib/Lib.cmi lib/Lib.mli
/usr/pkg/bin/ocamlc.opt -c -I pack -I lib -o pack/Packed.cmo pack/Packed.ml
/usr/pkg/bin/ocamlc.opt -pack pack/Packed.cmo -o Pack.cmo
/usr/pkg/bin/ocamlc.opt -c -I lib -o Main.cmo Main.ml
/usr/pkg/bin/ocamlc.opt Pack.cmo Main.cmo -o Main.byte
+ /usr/pkg/bin/ocamlc.opt Pack.cmo Main.cmo -o Main.byte
File "_none_", line 1, characters 0-1:
Error: Error while linking Pack.cmo:
Reference to undefined global `Lib'
Command exited with code 2.
This is with ocaml 3.11.1, but I obtain the same result with ocaml
3.12.0+beta1.
If I read the code correctly, this comes from the function prepare_link
in ocaml_compiler.ml which derives the dependencies from the files
.ml.depends and .mli.depends. But these files are not generated for
packs, hence the required dependencies are not build.
The attached small patch (patch-ocamlbuild-link-pack-deps.diff) simply
treats the .mlpack files as dependency files for packs, which fixes
the issue. This has been tested on a larger project with more nested
dependencies. But I'm new to ocamlbuild, and I may have overlooked
something.
Alternatively, the problem can be fixed with an ocamlbuild plugin that
generates appropriate %.ml.depends from %.mlpack. In case it helps
others encountering the same issue, I attach an implementation of such
a plugin.
If there is a better/simpler solution to this problem, please let me
know.
Thanks,
Grégoire Sutre
p.s. This byte-code linking problem with packs was reported to the list
two years ago [1], but with no answer.
[1]
http://caml.inria.fr/pub/ml-archives/caml-list/2008/06/784c154d0f7b53995c0167ac63fc5bb9.en.html
diff -Naur example/lib/Lib.ml example/lib/Lib.ml
--- example/lib/Lib.ml 1970-01-01 01:00:00.000000000 +0100
+++ example/lib/Lib.ml 2010-06-26 18:59:36.000000000 +0200
@@ -0,0 +1 @@
+let f () = ()
diff -Naur example/lib/Lib.mli example/lib/Lib.mli
--- example/lib/Lib.mli 1970-01-01 01:00:00.000000000 +0100
+++ example/lib/Lib.mli 2010-06-26 23:18:01.000000000 +0200
@@ -0,0 +1 @@
+val f : unit -> unit
diff -Naur example/Main.ml example/Main.ml
--- example/Main.ml 1970-01-01 01:00:00.000000000 +0100
+++ example/Main.ml 2010-06-26 23:26:54.000000000 +0200
@@ -0,0 +1 @@
+let _ = Pack.Packed.g ()
diff -Naur example/pack/Packed.ml example/pack/Packed.ml
--- example/pack/Packed.ml 1970-01-01 01:00:00.000000000 +0100
+++ example/pack/Packed.ml 2010-06-26 23:23:27.000000000 +0200
@@ -0,0 +1 @@
+let g () = Lib.f ()
diff -Naur example/Pack.mlpack example/Pack.mlpack
--- example/Pack.mlpack 1970-01-01 01:00:00.000000000 +0100
+++ example/Pack.mlpack 2010-06-26 23:24:30.000000000 +0200
@@ -0,0 +1 @@
+pack/Packed
diff -Naur example/_tags example/_tags
--- example/_tags 1970-01-01 01:00:00.000000000 +0100
+++ example/_tags 2010-06-26 23:24:57.000000000 +0200
@@ -0,0 +1,4 @@
+# include local sources
+<lib>: include
+
+<pack/*.cmx>: for-pack(Pack)
Index: ocamlbuild/ocaml_compiler.ml
===================================================================
--- ocamlbuild/ocaml_compiler.ml (revision 10605)
+++ ocamlbuild/ocaml_compiler.ml (working copy)
@@ -144,6 +144,12 @@
(if Pathname.exists (ml-.-"depends") then path_dependencies_of ml else
[])
(if Pathname.exists (mli-.-"depends") then path_dependencies_of mli else
[])
in
+ let modules =
+ if (modules = []) && (Pathname.exists (ml^"pack")) then
+ List.map (fun s -> (`mandatory, s)) (string_list_of_file (ml^"pack"))
+ else
+ modules
+ in
if modules <> [] && not (Hashtbl.mem cache_prepare_link key) then
let () = Hashtbl.add cache_prepare_link key true in
let modules' = List.map (fun (_, x) -> expand_module include_dirs x
extensions) modules in
(* Configuration **************************************************************)
(* Set to the list of directories containing *.mlpack files. *)
let mlpack_dirs = ["."]
(* Ocamlbuild Plugin Code *****************************************************)
open Ocamlbuild_plugin
module PackageLinkFix =
struct
let packages_in_dir dir =
Array.fold_right
(fun f l ->
if (Pathname.check_extension f "mlpack") then
(dir / (Pathname.remove_extension f)) :: l
else
l)
(Sys.readdir dir)
[]
let byte_dep_mlpack arg out env _build =
let arg = env arg and out = env out in
Echo (([arg; ":"] @
(List.map
(fun s -> " "^s)
(string_list_of_file (arg))) @
["\n"]), out)
let after_rules () =
begin
rule "ocaml dependencies mlpack"
~prod:"%.ml.depends"
~dep:"%.mlpack"
(byte_dep_mlpack "%.mlpack" "%.ml.depends")
;
List.iter
(fun p ->
dep
["ocaml"; "byte"; "pack"; "extension:cmo"; "file:"^p^".cmo"]
[p^".ml.depends"])
(List.concat (List.map packages_in_dir (List.map Pathname.mk
mlpack_dirs)))
end
end
;;
dispatch
begin
function
After_rules -> PackageLinkFix.after_rules ()
| _ -> ()
end
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