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

[Nate Foster <jnfoster@cs.cornell.edu>]

[-- Attachment #1: Type: text/plain, Size: 10619 bytes --]

+1

On Fri, Oct 28, 2016 at 7:28 AM, Jonathan DiLorenzo <
dilorenzo@cs.cornell.edu> wrote:

> 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
>>>>>>>>>
>>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>
>>>>>
>>>>
>>>
>>

[-- Attachment #2: Type: text/html, Size: 16683 bytes --]