Re: [Caml-list] Providing module implementations for Oasis

[Jonathan DiLorenzo <dilorenzo@cs.cornell.edu>]

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Thank you so much. That makes a lot of sense in hindsight, but I can't
quite imagine the situation that leads to me figuring it out.

On Oct 28, 2016 09:06, "Ivan Gotovchits" <ivg@ieee.org> wrote:

> The problem is that executable `ppx_forest` and library `forest_ppx` both
> refer to the same compilation
> unit `ppx_forest`.  So the solution is easy, just remove the `Ppx_forest`
> module from the library (indeed, it is not part of the library, it is the
> executable implementation).
> Here is the PR with the fix: https://github.com/padsproj/oforest/pull/9.
>
> # Details
>
> Just in case if you're interested why the resulting error was so confusing
> :)
>
> The error message came from the following compilation command:
>
>     ocamlfind ocamlopt -linkpkg -g -linkpkg -thread -package threads
> -package str -package re.str -package re.glob -package re -package
> ppx_tools.metaquot -package ppx_let -package ppx_deriving.show -package
> pads.ppx -package pads -package core -package compiler-libs.common
> ppx/forest_ppx.cmxa parsing/forest_parser.cmxa lib/forest.cmxa
> ppx/ppx_forest.cmx -o ppx/ppx_forest.native
>
>
> It is obvious that the command is incorrect (pun intended). Let's,
> actually, remove all the packages so that we can see the libraries:
>
>     ocamlfind ocamlopt -linkpkg ppx/forest_ppx.cmxa
> parsing/forest_parser.cmxa lib/forest.cmxa ppx/ppx_forest.cmx -o
> ppx/ppx_forest.native
>
> In fact, the problem is in library ordering. Modules and libraries must be
> sorted in topological order, so the first should be `lib/forest.cmxa`, then
> `parsing/forest_parser.cmxa` and finally `forest_ppx.cmxa`.
> And, yes, this is how this command looks after the fix:
>
>     ocamlfind ocamlopt -linkpkg lib/forest.cmxa parsing/forest_parser.cmxa
> ppx/forest_ppx.cmxa ppx/ppx_forest.cmx -o ppx/ppx_forest.native
>
> So how the toposort can be broken? My assumption, that this was because
> you introduced a loop into a dependency graph, when you added ppx_forest to
> both: the library and the executable.
> If my assumption is true, then probably we should add to ocamlbuild
> toposort routine an easy check that will detect loops and output  a proper
> diagnostic message if a dependency graph contains cycles.
>
> Regards,
> Ivan Gotovchits
>
>
> On Fri, Oct 28, 2016 at 2:14 AM, Jonathan DiLorenzo <
> dilorenzo@cs.cornell.edu> wrote:
>
>> Hmm, sadly this seems to still produce the same error after cleaning up
>> all the oasis generated files and everything:
>>
>> File "_none_", line 1:
>> Error: No implementations provided for the following modules:
>>          Forest_parser_helper referenced from ppx/forest_ppx.cmxa(Skins)
>> Command exited with code 2.
>>
>> Maybe notable (or maybe obvious) that if I switch oasis to use ocamlc
>> instead of ocamlopt, I instead get:
>>
>> File "_none_", line 1:
>> Error: Error while linking ppx/forest_ppx.cma(Skins):
>> Reference to undefined global `Forest_parser_helper'
>> Command exited with code 2.
>>
>> New _oasis file (not with best -> byte change):
>>
>> Library forest_parser
>>   Path:           parsing
>>   BuildTools:     ocamlbuild, menhir, ocamllex
>>   Findlibparent:  forest
>>   Findlibname:    forest_parser
>>   BuildDepends:   forest, ppx_deriving.show, compiler-libs.common
>>   CompiledObject: best
>>   Modules:  Forest_parser_helper, Forest_types
>>   InternalModules: Forest_lexer, Forest_parser
>>
>> Library forest_ppx
>>   Path:           ppx
>>   BuildTools:     ocamlbuild
>>   Findlibparent:  forest
>>   Findlibname:    forest_ppx
>>   BuildDepends:   re, re.str, forest.forest_parser, forest,
>> ppx_tools.metaquot
>>   CompiledObject: best
>>   Modules:        Ppx_forest
>>   InternalModules: Ppx_forest_lib, Utility, Skins
>>   XMETAEnable:    true
>>   XMETADescription: Syntax extension library for OCaml Forest
>>   XMETARequires:   str re core threads ppx_tools.metaquot
>>   XMETAExtraLines:  ppx = "ppx_forest"
>>
>> Executable ppx_forest
>>   Path:           ppx
>>   MainIs:         ppx_forest.ml
>>   BuildDepends:   forest, forest.forest_parser, forest.forest_ppx,
>> pads.ppx, ppx_tools.metaquot
>>   CompiledObject: best
>>
>>
>> On Thu, Oct 27, 2016 at 2:24 PM, Ivan Gotovchits <ivg@ieee.org> wrote:
>>
>>> The problem is  in a name clashing between `$opam-switch/lib/ocaml/compiler-libs/parser`
>>> and the `parser` library that is compiled from your internal library named
>>> `parser.cmxa`.
>>> The compiler-lib is added to the search path by the `ppx_tools` library,
>>> and when you're trying to link your final executable, it takes the wrong
>>> archive, that definitely doesn't have
>>> `Forest_parser_helper` module.
>>>
>>> The reason, why it is still able to see that there is no `bad_func` in
>>> `Forest_parser_helper` is because the interfaces are not contained in the
>>> `cmxa` file, but are looked up directly in
>>> the `cmi`. Compiler is looking for a file named
>>> `forest_parser_helper.cmi` and can see that there are not `bad_func` there.
>>>
>>> The solution is to rename your library, e.g., use `Library
>>> forest_parser` instead of `Library parser`
>>>
>>> On Thu, Oct 27, 2016 at 1:44 PM, Jonathan DiLorenzo <
>>> dilorenzo@cs.cornell.edu> wrote:
>>>
>>>> Hey,
>>>>
>>>> Ok, now the next step would be the following. Carefully check that all
>>>>> modules, that you're using in libraries are included in `Modules` or
>>>>> `InternalModules`. It is the case
>>>>> that sometimes when you forgot to include a module, oasis (actually
>>>>> `ocamlbuild`), may produce a strange, and on a first glance, irrelevant
>>>>> error message.
>>>>>
>>>>
>>>> I checked and sadly the modules I'm trying to access are all in
>>>> `Modules`. Perhaps interestingly, it can still clearly detect statically if
>>>> the function exists or not because if I try to use a function that doesn't
>>>> exist it instead gives me this error (which is what I would normally
>>>> expect):
>>>>
>>>> File "ppx/skins.ml", line 39, characters 8-37:
>>>> Error: Unbound value Forest_parser_helper.bad_func
>>>> Command exited with code 2.
>>>>
>>>>
>>>>> If it doesn't help then the `_build/_log` file might help us to debug
>>>>> the issue.
>>>>>
>>>>
>>>> Attached. Thanks so much for helping with this again. I'm at a total
>>>> loss.
>>>>
>>>>
>>>>>
>>>>> On Thu, Oct 27, 2016 at 10:59 AM, Jonathan DiLorenzo <
>>>>> dilorenzo@cs.cornell.edu> wrote:
>>>>>
>>>>>> Hey Ivan,
>>>>>>
>>>>>> Thanks for your response.
>>>>>>
>>>>>> The first one is that you didn't run `oasis setup` after you made the
>>>>>>> changes, so I would suggest cleaning current state
>>>>>>> and starting from scratch. (I usually just do `git clean -idx` just
>>>>>>> to be sure that I got rid of any generated files, like setup.data, et alas,
>>>>>>> but be careful,
>>>>>>> don't delete something that you need).
>>>>>>>
>>>>>>
>>>>>> I tried cleaning up all the generated files. Same error unfortunately
>>>>>>
>>>>>>
>>>>>>> Another idea is that you're using oasis 0.4.7 with
>>>>>>> ocaml-4.03.0+flambda, they are currently incompatible, and can produce
>>>>>>> weird bugs. If that so, then consider switching
>>>>>>> either a compiler or oasis to different versions.
>>>>>>>
>>>>>>
>>>>>> I am using oasis 0.4.7 and ocaml-4.03.0, but I don't appear to be
>>>>>> using flambda. I tried passing in -config and it said that flambda was
>>>>>> false at least, but I admit, I'm not especially familiar with it, so if
>>>>>> there's some other way I should be checking for this please let me know.
>>>>>> Hopefully, they're compatible sans flambda?
>>>>>>
>>>>>>
>>>>>> On Thu, Oct 27, 2016 at 1:01 AM, Jonathan DiLorenzo <
>>>>>>> dilorenzo@cs.cornell.edu> wrote:
>>>>>>>
>>>>>>>> Hey all,
>>>>>>>>
>>>>>>>> I'm trying to build my system using Oasis and OCamlbuild. I have 3
>>>>>>>> different libraries and for some reason I seem to only be able to refer
>>>>>>>> from one to the other in seemingly random files. For example, I want my
>>>>>>>> 'ppx' library to be able to use functions from my 'parser' library. One
>>>>>>>> file (ppx_forest.ml) can use functions from it, while another in
>>>>>>>> the same library (skins.ml) cannot, giving me this error:
>>>>>>>>
>>>>>>>> File "_none_", line 1:
>>>>>>>> Error: No implementations provided for the following modules:
>>>>>>>>          Forest_parser_helper referenced from ppx/ppx.cmxa(Skins)
>>>>>>>> Command exited with code 2.
>>>>>>>>
>>>>>>>> They can all refer to types I've defined therein though.
>>>>>>>>
>>>>>>>> I'm not fantastic at Oasis so maybe I'm just missing something
>>>>>>>> basic? Any ideas? Any more information I can gather to give more context
>>>>>>>> otherwise?
>>>>>>>>
>>>>>>>> Thanks in advance,
>>>>>>>> Jonathan
>>>>>>>>
>>>>>>>> Excerpt of my Oasis file that may possibly be relevant:
>>>>>>>>
>>>>>>>> Library forest
>>>>>>>>   Path:          lib
>>>>>>>>   BuildTools:    ocamlbuild
>>>>>>>>   BuildDepends:   pads, str, re, re.glob, core, threads, ppx_let
>>>>>>>>   CompiledObject: best
>>>>>>>>   Modules:       Forest, PadsInterface
>>>>>>>>
>>>>>>>> Library parser
>>>>>>>>   Path:           parsing
>>>>>>>>   BuildTools:     ocamlbuild, menhir, ocamllex
>>>>>>>>   Findlibparent:  forest
>>>>>>>>   Findlibname:    parser
>>>>>>>>   BuildDepends:   forest, ppx_deriving.show, compiler-libs.common
>>>>>>>>   CompiledObject: best
>>>>>>>>   Modules:  Forest_parser_helper
>>>>>>>>   InternalModules: Forest_lexer, Forest_parser, Forest_types
>>>>>>>>
>>>>>>>> Library ppx
>>>>>>>>   Path:           ppx
>>>>>>>>   BuildTools:     ocamlbuild
>>>>>>>>   Findlibparent:  forest
>>>>>>>>   Findlibname:    ppx
>>>>>>>>   BuildDepends:   re, re.str, forest.parser, forest,
>>>>>>>> ppx_tools.metaquot
>>>>>>>>   CompiledObject: best
>>>>>>>>   Modules:        Ppx_forest
>>>>>>>>   InternalModules: Ppx_forest_lib, Utility, Skins
>>>>>>>>   XMETAEnable:    true
>>>>>>>>   XMETARequires:   str re core threads ppx_tools.metaquot
>>>>>>>>   XMETAExtraLines:  ppx = "ppx_forest"
>>>>>>>>
>>>>>>>> Executable ppx_forest
>>>>>>>>   Path:           ppx
>>>>>>>>   MainIs:         ppx_forest.ml
>>>>>>>>   BuildDepends:   forest, forest.parser, forest.ppx, pads.ppx,
>>>>>>>> ppx_tools.metaquot
>>>>>>>>   CompiledObject: best
>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>
>>>>>
>>>>
>>>
>>
>

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