Missing -I when building against a virtual library from another project

[rlepigre]

I am having a weird issue with a library containing a bunch of modules and one virtual_modules.
(The problem arises both with dune.2.0.1 and dune 2.6.1, I have not tried other versions.)

First, when the library is installed, no .cma or .cmxa files are installed by dune, and the META file has empty fields:

package "my_lib" (
  ...
  archive(byte) = ""
  archive(native) = ""
  plugin(byte) = ""
  plugin(native) = ""
)

Is that expected behaviour? I could find no clear explanation about that in the doc.

Second, and that is really the origin of my problem, when I try to compile another project depending on the virtual library, no corresponding -I option is generated. I am currently working around that using:

 (flags (:standard -I +../my_package/my_lib)) ; FIXME crazy hack.

with which everything works as expected. However, I feel like I should not have to do that, and my fix is really fragile due to the explicit path.

Unfortunately I cannot give access to the sources of the project (it is not currently open-source, and I am not sure how much information I can give about it). However, here is what the dune file of the library looks like (it is used by other libraries and executables of the same project):

; The library containing a virtual module
(library
 (name my_lib)
 (public_name my_package.my_lib)
 (synopsis "...")
 (modules :standard)
 (virtual_modules virtual)
 (libraries ...))

And here is what the dune file of the (independent) project trying to use the library looks like:

; The executable trying to use the library with the virtual module
(executable
 (name main)
 (public_name my_program)
 (package my_other_package)
 (flags (:standard -w -27 -I +../my_package/my_lib)) ; FIXME crazy hack.
 (libraries cmdliner str unix ... my_package.my_lib my_package.impl_of_virt))

[ghost]

For the META file, yes that's expected. It's because at the moment ocamlfind doesn't support virtual libraries. For the -I, that is very suspicious indeed and you are right that it is not something you should do.

What does dune output when you don't add this -I?

[rlepigre]

OK, thanks, that makes sense.

The output is the following:

File "my_dir/file.ml", line 1, characters 5-18:
Error: Unbound module My_module
File "my_dir/file.mli", line 3, characters 41-76:
Error: Unbound module My_module

[ghost]

That's really odd. It looks like a standard use case of virtual libraries. However, it's a bit difficult for us to investigate without a minimal reproduction case. :(

[rlepigre]

Yeah, that is annoying. In fact, luckily, I can now produce a reproduction case since a publicly available version of the library we are using has become available today here: https://github.com/rems-project/cerberus. You just need to pin it with:

opam pin add -y cerberus git+https://github.com/rems-project/cerberus.git

(I know for sure this works with OCaml 4.07.1.)

The file buggy.tar.gz contains a minimal example to reproduce the problem, you can comment/uncomment the hackish fix in the dune file.

[ghost]

Thanks for sending a minimal example. @rgrinberg could you have a look at this?

[rgrinberg]

@rlepigre could you check if it's still an issue in 2.7? I'm unable to reproduce this with the latest version of dune.

[rlepigre]

Yes, I can reproduce with dune 2.7 (and the example from the archive linked above).

$> dune --version
2.7.0
$> dune build
File "main.ml", line 1, characters 5-18:
Error: Unbound module Cerb_frontend

What version of OCaml are you using?

[rlepigre]

Actually I forgot to recompile the library with the new version. I'll do that later and tell you if that does the trick.

Edit: I can still reproduce the bug, even after installing the dependency with dune.

[rgrinberg]

Could you try out master as well?

[rlepigre]

Yep, still fails with version 2.7.0-69-g1f3c32801.

Note however that with this version of dune the package I depend on must be fixed slightly, by adding a dependency to the result package in backend/driver/dune. I guess this is due to a bug fix in dune, since my package should never have been able to depend on result without an explicit dependency.

[rgrinberg]

I see. Could you show the contents of your dune-package file of the cerb package? It should be either in the _build directory or installed in ~/.opam/<switch>/lib/...

[rlepigre]

Here it is:

(lang dune 2.7)
(name cerberus)
(version da87de0)
(library
 (name cerberus.backend_common)
 (kind normal)
 (synopsis "Cerberus backend utilities")
 (archives
  (byte backend_common/cerb_backend.cma)
  (native backend_common/cerb_backend.cmxa))
 (plugins
  (byte backend_common/cerb_backend.cma)
  (native backend_common/cerb_backend.cmxs))
 (foreign_objects backend_common/cerberus_cstubs.o)
 (foreign_archives backend_common/libcerb_backend_stubs.a)
 (native_archives backend_common/cerb_backend.a)
 (requires
  cerberus.frontend
  cerberus.core_parser
  cerberus.c_parser
  pprint
  cerberus.util
  z3)
 (main_module_name Cerb_backend)
 (modes byte native)
 (modules
  (wrapped
   (main_module_name Cerb_backend)
   (modules
    ((name Auxl) (obj_name cerb_backend__Auxl) (visibility public) (impl))
    ((name Dot) (obj_name cerb_backend__Dot) (visibility public) (impl))
    ((name Exhaustive_driver)
     (obj_name cerb_backend__Exhaustive_driver)
     (visibility public)
     (impl)
     (intf))
    ((name Fs_ocaml)
     (obj_name cerb_backend__Fs_ocaml)
     (visibility public)
     (impl))
    ((name Pipeline)
     (obj_name cerb_backend__Pipeline)
     (visibility public)
     (impl)
     (intf)))
   (alias_module
    (name Cerb_backend)
    (obj_name cerb_backend)
    (visibility public)
    (kind alias)
    (impl))
   (wrapped true))))
(library
 (name cerberus.c_parser)
 (kind normal)
 (synopsis "C parser")
 (archives (byte c_parser/c_parser.cma) (native c_parser/c_parser.cmxa))
 (plugins (byte c_parser/c_parser.cma) (native c_parser/c_parser.cmxs))
 (native_archives c_parser/c_parser.a)
 (requires cerberus.frontend)
 (modes byte native)
 (modules
  (unwrapped
   ((name C_lexer) (obj_name c_lexer) (visibility public) (impl))
   ((name C_parser) (obj_name c_parser) (visibility public) (impl) (intf))
   ((name C_parser_driver)
    (obj_name c_parser_driver)
    (visibility public)
    (impl))
   ((name Lexer_feedback)
    (obj_name lexer_feedback)
    (visibility public)
    (impl)
    (intf))
   ((name Tokens) (obj_name tokens) (visibility public) (impl)))))
(library
 (name cerberus.core_parser)
 (kind normal)
 (synopsis "Core parser")
 (archives
  (byte core_parser/core_parser.cma)
  (native core_parser/core_parser.cmxa))
 (plugins
  (byte core_parser/core_parser.cma)
  (native core_parser/core_parser.cmxs))
 (native_archives core_parser/core_parser.a)
 (requires cerberus.frontend)
 (modes byte native)
 (modules
  (unwrapped
   ((name Core_lexer) (obj_name core_lexer) (visibility public) (impl))
   ((name Core_parser)
    (obj_name core_parser)
    (visibility public)
    (impl)
    (intf))
   ((name Core_parser_driver)
    (obj_name core_parser_driver)
    (visibility public)
    (impl))
   ((name Core_parser_util)
    (obj_name core_parser_util)
    (visibility public)
    (impl)))))
(library
 (name cerberus.frontend)
 (kind normal)
 (virtual)
 (synopsis "Cerberus frontend")
 (native_archives frontend/cerb_frontend.a)
 (requires lem pprint cerberus.util cerberus.sibylfs)
 (main_module_name Cerb_frontend)
 (modes byte native)
 (modules
  (wrapped
   (main_module_name Cerb_frontend)
   (modules
    ((name AilSyntax)
     (obj_name cerb_frontend__AilSyntax)
     (visibility public)
     (impl))
    ((name AilSyntaxAux)
     (obj_name cerb_frontend__AilSyntaxAux)
     (visibility public)
     (impl))
    ((name AilTypesAux)
     (obj_name cerb_frontend__AilTypesAux)
     (visibility public)
     (impl))
    ((name AilTyping)
     (obj_name cerb_frontend__AilTyping)
     (visibility public)
     (impl))
    ((name AilWf) (obj_name cerb_frontend__AilWf) (visibility public) (impl))
    ((name Annot) (obj_name cerb_frontend__Annot) (visibility public) (impl))
    ((name Any) (obj_name cerb_frontend__Any) (visibility public) (impl))
    ((name Ast_core)
     (obj_name cerb_frontend__Ast_core)
     (visibility public)
     (impl))
    ((name Bimap) (obj_name cerb_frontend__Bimap) (visibility public) (impl))
    ((name Boot) (obj_name cerb_frontend__Boot) (visibility public) (impl))
    ((name Boot_printf)
     (obj_name cerb_frontend__Boot_printf)
     (visibility public)
     (impl)
     (intf))
    ((name Builtins)
     (obj_name cerb_frontend__Builtins)
     (visibility public)
     (impl))
    ((name Cabs) (obj_name cerb_frontend__Cabs) (visibility public) (impl))
    ((name Cabs_to_ail)
     (obj_name cerb_frontend__Cabs_to_ail)
     (visibility public)
     (impl))
    ((name Cabs_to_ail_aux)
     (obj_name cerb_frontend__Cabs_to_ail_aux)
     (visibility public)
     (impl))
    ((name Cabs_to_ail_effect)
     (obj_name cerb_frontend__Cabs_to_ail_effect)
     (visibility public)
     (impl))
    ((name Cmm_aux)
     (obj_name cerb_frontend__Cmm_aux)
     (visibility public)
     (impl))
    ((name Cmm_csem)
     (obj_name cerb_frontend__Cmm_csem)
     (visibility public)
     (impl))
    ((name Cmm_op)
     (obj_name cerb_frontend__Cmm_op)
     (visibility public)
     (impl))
    ((name Constraint)
     (obj_name cerb_frontend__Constraint)
     (visibility public)
     (impl))
    ((name Core) (obj_name cerb_frontend__Core) (visibility public) (impl))
    ((name Core_anormalise)
     (obj_name cerb_frontend__Core_anormalise)
     (visibility public)
     (impl))
    ((name Core_aux)
     (obj_name cerb_frontend__Core_aux)
     (visibility public)
     (impl))
    ((name Core_ctype_aux)
     (obj_name cerb_frontend__Core_ctype_aux)
     (visibility public)
     (impl))
    ((name Core_eval)
     (obj_name cerb_frontend__Core_eval)
     (visibility public)
     (impl))
    ((name Core_indet)
     (obj_name cerb_frontend__Core_indet)
     (visibility public)
     (impl))
    ((name Core_linking)
     (obj_name cerb_frontend__Core_linking)
     (visibility public)
     (impl))
    ((name Core_peval)
     (obj_name cerb_frontend__Core_peval)
     (visibility public)
     (impl))
    ((name Core_remove_unused_functions)
     (obj_name cerb_frontend__Core_remove_unused_functions)
     (visibility public)
     (impl))
    ((name Core_rewrite)
     (obj_name cerb_frontend__Core_rewrite)
     (visibility public)
     (impl))
    ((name Core_rewriter)
     (obj_name cerb_frontend__Core_rewriter)
     (visibility public)
     (impl))
    ((name Core_run)
     (obj_name cerb_frontend__Core_run)
     (visibility public)
     (impl))
    ((name Core_run_aux)
     (obj_name cerb_frontend__Core_run_aux)
     (visibility public)
     (impl))
    ((name Core_sequentialise)
     (obj_name cerb_frontend__Core_sequentialise)
     (visibility public)
     (impl))
    ((name Core_typing)
     (obj_name cerb_frontend__Core_typing)
     (visibility public)
     (impl))
    ((name Core_typing_aux)
     (obj_name cerb_frontend__Core_typing_aux)
     (visibility public)
     (impl))
    ((name Core_typing_effect)
     (obj_name cerb_frontend__Core_typing_effect)
     (visibility public)
     (impl))
    ((name Core_unstruct)
     (obj_name cerb_frontend__Core_unstruct)
     (visibility public)
     (impl))
    ((name Ctype) (obj_name cerb_frontend__Ctype) (visibility public) (impl))
    ((name Debug) (obj_name cerb_frontend__Debug) (visibility public) (impl))
    ((name Decode)
     (obj_name cerb_frontend__Decode)
     (visibility public)
     (impl))
    ((name Decode_ocaml)
     (obj_name cerb_frontend__Decode_ocaml)
     (visibility public)
     (impl))
    ((name Defacto_memory)
     (obj_name cerb_frontend__Defacto_memory)
     (visibility public)
     (impl))
    ((name Defacto_memory_aux)
     (obj_name cerb_frontend__Defacto_memory_aux)
     (visibility public)
     (impl))
    ((name Defacto_memory_types)
     (obj_name cerb_frontend__Defacto_memory_types)
     (visibility public)
     (impl))
    ((name Dlist) (obj_name cerb_frontend__Dlist) (visibility public) (impl))
    ((name Driver)
     (obj_name cerb_frontend__Driver)
     (visibility public)
     (impl))
    ((name Enum) (obj_name cerb_frontend__Enum) (visibility public) (impl))
    ((name ErrorMonad)
     (obj_name cerb_frontend__ErrorMonad)
     (visibility public)
     (impl))
    ((name Errors)
     (obj_name cerb_frontend__Errors)
     (visibility public)
     (impl))
    ((name Exception)
     (obj_name cerb_frontend__Exception)
     (visibility public)
     (impl))
    ((name Exception_undefined)
     (obj_name cerb_frontend__Exception_undefined)
     (visibility public)
     (impl))
    ((name Float) (obj_name cerb_frontend__Float) (visibility public) (impl))
    ((name Fs) (obj_name cerb_frontend__Fs) (visibility public) (impl))
    ((name GenTypes)
     (obj_name cerb_frontend__GenTypes)
     (visibility public)
     (impl))
    ((name GenTypesAux)
     (obj_name cerb_frontend__GenTypesAux)
     (visibility public)
     (impl))
    ((name GenTyping)
     (obj_name cerb_frontend__GenTyping)
     (visibility public)
     (impl))
    ((name Global)
     (obj_name cerb_frontend__Global)
     (visibility public)
     (impl))
    ((name Impl_mem)
     (obj_name cerb_frontend__Impl_mem)
     (visibility public)
     (kind virtual)
     (intf))
    ((name Implementation)
     (obj_name cerb_frontend__Implementation)
     (visibility public)
     (impl))
    ((name IntegerImpl)
     (obj_name cerb_frontend__IntegerImpl)
     (visibility public)
     (impl))
    ((name Linux) (obj_name cerb_frontend__Linux) (visibility public) (impl))
    ((name Loc) (obj_name cerb_frontend__Loc) (visibility public) (impl))
    ((name Mem) (obj_name cerb_frontend__Mem) (visibility public) (impl))
    ((name Mem_aux)
     (obj_name cerb_frontend__Mem_aux)
     (visibility public)
     (impl))
    ((name Mem_common)
     (obj_name cerb_frontend__Mem_common)
     (visibility public)
     (impl))
    ((name Memory_model)
     (obj_name cerb_frontend__Memory_model)
     (visibility public)
     (impl))
    ((name Monadic_parsing)
     (obj_name cerb_frontend__Monadic_parsing)
     (visibility public)
     (impl))
    ((name Mucore)
     (obj_name cerb_frontend__Mucore)
     (visibility public)
     (impl))
    ((name Mucore_to_core)
     (obj_name cerb_frontend__Mucore_to_core)
     (visibility public)
     (impl))
    ((name Multiset)
     (obj_name cerb_frontend__Multiset)
     (visibility public)
     (impl))
    ((name Nondeterminism)
     (obj_name cerb_frontend__Nondeterminism)
     (visibility public)
     (impl))
    ((name Ocaml_gcc_builtins)
     (obj_name cerb_frontend__Ocaml_gcc_builtins)
     (visibility public)
     (impl))
    ((name Ocaml_implementation)
     (obj_name cerb_frontend__Ocaml_implementation)
     (visibility public)
     (impl))
    ((name Output)
     (obj_name cerb_frontend__Output)
     (visibility public)
     (impl))
    ((name Pp) (obj_name cerb_frontend__Pp) (visibility public) (impl))
    ((name Pp_ail)
     (obj_name cerb_frontend__Pp_ail)
     (visibility public)
     (impl)
     (intf))
    ((name Pp_ail_ast)
     (obj_name cerb_frontend__Pp_ail_ast)
     (visibility public)
     (impl))
    ((name Pp_ail_raw)
     (obj_name cerb_frontend__Pp_ail_raw)
     (visibility public)
     (impl))
    ((name Pp_ast)
     (obj_name cerb_frontend__Pp_ast)
     (visibility public)
     (impl))
    ((name Pp_cabs)
     (obj_name cerb_frontend__Pp_cabs)
     (visibility public)
     (impl)
     (intf))
    ((name Pp_core)
     (obj_name cerb_frontend__Pp_core)
     (visibility public)
     (impl)
     (intf))
    ((name Pp_core_ctype)
     (obj_name cerb_frontend__Pp_core_ctype)
     (visibility public)
     (impl))
    ((name Pp_defacto_memory)
     (obj_name cerb_frontend__Pp_defacto_memory)
     (visibility public)
     (impl)
     (intf))
    ((name Pp_errors)
     (obj_name cerb_frontend__Pp_errors)
     (visibility public)
     (impl))
    ((name Pp_mem)
     (obj_name cerb_frontend__Pp_mem)
     (visibility public)
     (impl)
     (intf))
    ((name Pp_mucore)
     (obj_name cerb_frontend__Pp_mucore)
     (visibility public)
     (impl))
    ((name Pp_run)
     (obj_name cerb_frontend__Pp_run)
     (visibility public)
     (impl))
    ((name Pp_std)
     (obj_name cerb_frontend__Pp_std)
     (visibility public)
     (impl))
    ((name Pp_symbol)
     (obj_name cerb_frontend__Pp_symbol)
     (visibility public)
     (impl)
     (intf))
    ((name Pp_trace)
     (obj_name cerb_frontend__Pp_trace)
     (visibility public)
     (impl))
    ((name Pp_utils)
     (obj_name cerb_frontend__Pp_utils)
     (visibility public)
     (impl))
    ((name Product)
     (obj_name cerb_frontend__Product)
     (visibility public)
     (impl))
    ((name Range) (obj_name cerb_frontend__Range) (visibility public) (impl))
    ((name Remove_unspecs)
     (obj_name cerb_frontend__Remove_unspecs)
     (visibility public)
     (impl))
    ((name Scope_table)
     (obj_name cerb_frontend__Scope_table)
     (visibility public)
     (impl))
    ((name Smt2) (obj_name cerb_frontend__Smt2) (visibility public) (impl))
    ((name State) (obj_name cerb_frontend__State) (visibility public) (impl))
    ((name State_exception)
     (obj_name cerb_frontend__State_exception)
     (visibility public)
     (impl))
    ((name State_exception_undefined)
     (obj_name cerb_frontend__State_exception_undefined)
     (visibility public)
     (impl))
    ((name Std) (obj_name cerb_frontend__Std) (visibility public) (impl))
    ((name String_ail)
     (obj_name cerb_frontend__String_ail)
     (visibility public)
     (impl))
    ((name String_cabs)
     (obj_name cerb_frontend__String_cabs)
     (visibility public)
     (impl))
    ((name String_core)
     (obj_name cerb_frontend__String_core)
     (visibility public)
     (impl))
    ((name String_core_ctype)
     (obj_name cerb_frontend__String_core_ctype)
     (visibility public)
     (impl))
    ((name String_core_run)
     (obj_name cerb_frontend__String_core_run)
     (visibility public)
     (impl))
    ((name String_defacto_memory)
     (obj_name cerb_frontend__String_defacto_memory)
     (visibility public)
     (impl))
    ((name String_mem)
     (obj_name cerb_frontend__String_mem)
     (visibility public)
     (impl))
    ((name String_nat_big_num)
     (obj_name cerb_frontend__String_nat_big_num)
     (visibility public)
     (impl)
     (intf))
    ((name String_symbol)
     (obj_name cerb_frontend__String_symbol)
     (visibility public)
     (impl))
    ((name Switches)
     (obj_name cerb_frontend__Switches)
     (visibility public)
     (impl)
     (intf))
    ((name Symbol)
     (obj_name cerb_frontend__Symbol)
     (visibility public)
     (impl))
    ((name Tags)
     (obj_name cerb_frontend__Tags)
     (visibility public)
     (impl)
     (intf))
    ((name Trace_event)
     (obj_name cerb_frontend__Trace_event)
     (visibility public)
     (impl))
    ((name Translation)
     (obj_name cerb_frontend__Translation)
     (visibility public)
     (impl))
    ((name Translation_aux)
     (obj_name cerb_frontend__Translation_aux)
     (visibility public)
     (impl))
    ((name Translation_effect)
     (obj_name cerb_frontend__Translation_effect)
     (visibility public)
     (impl))
    ((name TypingError)
     (obj_name cerb_frontend__TypingError)
     (visibility public)
     (impl))
    ((name Undefined)
     (obj_name cerb_frontend__Undefined)
     (visibility public)
     (impl))
    ((name Utils) (obj_name cerb_frontend__Utils) (visibility public) (impl))
    ((name Version)
     (obj_name cerb_frontend__Version)
     (visibility public)
     (impl))
    ((name WipFrontend)
     (obj_name cerb_frontend__WipFrontend)
     (visibility public)
     (impl)))
   (alias_module
    (name Cerb_frontend)
    (obj_name cerb_frontend)
    (visibility public)
    (kind alias)
    (impl))
   (wrapped true))))
(library
 (name cerberus.mem.concrete)
 (kind normal)
 (archives
  (byte mem/concrete/mem_concrete.cma)
  (native mem/concrete/mem_concrete.cmxa))
 (plugins
  (byte mem/concrete/mem_concrete.cma)
  (native mem/concrete/mem_concrete.cmxs))
 (native_archives mem/concrete/mem_concrete.a)
 (requires cerberus.frontend)
 (implements cerberus.frontend)
 (main_module_name Cerb_frontend)
 (modes byte native)
 (modules
  (wrapped
   (main_module_name Cerb_frontend)
   (modules
    ((name Impl_mem)
     (obj_name cerb_frontend__Impl_mem)
     (visibility public)
     (kind impl_vmodule)
     (impl)))
   (alias_module
    (name Cerb_frontend__mem_concrete__)
    (obj_name cerb_frontend__mem_concrete__)
    (visibility public)
    (kind alias)
    (impl))
   (wrapped true))))
(library
 (name cerberus.mem.symbolic)
 (kind normal)
 (archives
  (byte mem/symbolic/mem_symbolic.cma)
  (native mem/symbolic/mem_symbolic.cmxa))
 (plugins
  (byte mem/symbolic/mem_symbolic.cma)
  (native mem/symbolic/mem_symbolic.cmxs))
 (native_archives mem/symbolic/mem_symbolic.a)
 (requires cerberus.frontend z3)
 (implements cerberus.frontend)
 (main_module_name Cerb_frontend)
 (modes byte native)
 (obj_dir (private_dir .private))
 (modules
  (wrapped
   (main_module_name Cerb_frontend)
   (modules
    ((name Impl_mem)
     (obj_name cerb_frontend__Impl_mem)
     (visibility public)
     (kind impl_vmodule)
     (impl))
    ((name Mem_simplify)
     (obj_name cerb_frontend__mem_symbolic____Mem_simplify)
     (visibility private)
     (impl)))
   (alias_module
    (name Cerb_frontend__mem_symbolic__)
    (obj_name cerb_frontend__mem_symbolic__)
    (visibility public)
    (kind alias)
    (impl))
   (wrapped true))))
(library
 (name cerberus.sibylfs)
 (kind normal)
 (synopsis Sibylfs)
 (archives (byte sibylfs/sibylfs.cma) (native sibylfs/sibylfs.cmxa))
 (plugins (byte sibylfs/sibylfs.cma) (native sibylfs/sibylfs.cmxs))
 (native_archives sibylfs/sibylfs.a)
 (requires sha lem ppx_sexp_conv sexplib ppx_sexp_conv.runtime-lib)
 (modes byte native)
 (modules
  (unwrapped
   ((name Abstract_string)
    (obj_name abstract_string)
    (visibility public)
    (impl)
    (intf))
   ((name Dir_heap) (obj_name dir_heap) (visibility public) (impl))
   ((name Fs_dict_wrappers)
    (obj_name fs_dict_wrappers)
    (visibility public)
    (impl)
    (intf))
   ((name Fs_dump) (obj_name fs_dump) (visibility public) (impl))
   ((name Fs_prelude) (obj_name fs_prelude) (visibility public) (impl))
   ((name Fs_printer) (obj_name fs_printer) (visibility public) (impl))
   ((name Fs_spec) (obj_name fs_spec) (visibility public) (impl))
   ((name Lem_support)
    (obj_name lem_support)
    (visibility public)
    (impl)
    (intf))
   ((name List_array) (obj_name list_array) (visibility public) (impl))
   ((name Sibylfs) (obj_name sibylfs) (visibility public) (impl)))))
(library
 (name cerberus.util)
 (kind normal)
 (synopsis "Cerberus util library")
 (archives (byte util/util.cma) (native util/util.cmxa))
 (plugins (byte util/util.cma) (native util/util.cmxs))
 (native_archives util/util.a)
 (requires lem pprint yojson)
 (modes byte native)
 (modules
  (unwrapped
   ((name Cerb_runtime)
    (obj_name cerb_runtime)
    (visibility public)
    (impl)
    (intf))
   ((name Colour) (obj_name colour) (visibility public) (impl) (intf))
   ((name Debug_ocaml)
    (obj_name debug_ocaml)
    (visibility public)
    (impl)
    (intf))
   ((name Floating) (obj_name floating) (visibility public) (impl))
   ((name Fresh) (obj_name fresh) (visibility public) (impl))
   ((name Global_ocaml)
    (obj_name global_ocaml)
    (visibility public)
    (impl)
    (intf))
   ((name Json) (obj_name json) (visibility public) (impl))
   ((name Location_ocaml)
    (obj_name location_ocaml)
    (visibility public)
    (impl)
    (intf))
   ((name Logging) (obj_name logging) (visibility public) (impl) (intf))
   ((name N1570) (obj_name n1570) (visibility public) (impl))
   ((name Ocaml_any) (obj_name ocaml_any) (visibility public) (impl))
   ((name Pp_prelude) (obj_name pp_prelude) (visibility public) (impl) (intf))
   ((name Util) (obj_name util) (visibility public) (impl)))))

[rgrinberg]

Thanks. Unfortunately, I remain confused.

When I reproduced the bug with an older version of dune, I noticed that the requires field was missing for libraries with implements. Adding that missing field back fixed the problem, and recent versions of dune added the requires field correctly.

It seems like you're experiencing the same problem even when the requires field is set. Which is something I haven't reproduced myself :/

[rlepigre]

OK, so do you mean that everything should work with dune 2.7.0 or higher?
I'm currently creating a fresh opam switch to test things again, maybe I made a mistake in my previous attempts at testing (though I doubt it since I was careful).

[rlepigre]

I managed to reproduce the problem once again using the following procedure:

# Run the following in an initially empty directory.
$> opam switch create . ocaml-base-compiler.4.07.1
$> opam pin add -n -y cerberus git+https://github.com/rlepigre/cerberus.git
$> opam install dune.2.7.0 cerberus
$> wget https://github.com/ocaml/dune/files/4955076/buggy.tar.gz
$> tar xf buggy.tar.gz
$> cd buggy
$> dune build
File "main.ml", line 1, characters 5-18:
Error: Unbound module Cerb_frontend

Edit: note that you can pin cerberus to git+https://github.com/rlepigre/cerberus.git to get a version that works with most recent dune.

[rgrinberg]

Okay, I'm able to reproduce. Thanks.

[vzaliva]

I am running into the same problem. The workaround suggested by @rlepigre to add -I flag:

 (flags (:standard -w -27 -I +../cerberus/frontend)) 

made it compile when invoking dune from the command line.
However, in my emacs (using merlin) it still shows module import errors.

[vzaliva]

Merlin issue seems to be unrelated to this: ocaml/merlin#1388