Re: [Caml-list] Interface(.mli) location

[moosotc@gmail.com]

David Allsopp <dra-news@metastack.com> writes:

> moosotc@gmail.com wrote:
>> David Allsopp <dra-news@metastack.com> writes:
>> > moosotc@gmail.com wrote:
>> >> David Allsopp <dra-news@metastack.com> writes:
>> >> > moosotc@gmail.com wrote:
>> >> >> Gabriel Scherer <gabriel.scherer@gmail.com> writes:
>> >> >>
>> >> >> > It is correct that ocamldep assumes that the .ml and .mli of a
>> >> >> > given module are at the same place, but this is not the case for
>> >> >> > the rest of the compilation chain, which is either concerned
>> >> >> > with single source files (a .ml file or a .mli file) or with
>> >> >> > "compilation units" (a .cmo and .cmi files passed together,
>> >> >> > independently of where their source files were). In particular,
>> >> >> > all type-checking tools do look in -I directories to find .cmi
>> >> >> > files for the dependencies of the module being compiled (and at
>> >> >> > this stage
>> >> they do not care for .mli files).
>> >> >>
>> >> >> But the script seems to (somewhat) contradict this, i.e. after
>> >> >> `ocamlc -I d -c a.ml' ocamlc ignores the presence of .mli inside
>> >> >> subdirectory d/, producing both .cmi/.cmo when when compiling a.ml.
>> >> >
>> >> > The -I option specifies extra directories for compiled files only,
>> >> > so it's correct that the compiler ignores d/a.mli.
>> >>
>> >> After sending the first post I've realized that: ocamlc -c d/a.mli
>> >> was forgotten, but even after adding that to the script things do not
>> >> change, i.e. following compilation of a.ml with -I d where d contains
>> >> a.cmi still produces both a.cmo and a.cmi in the top-level directory.
>> >
>> > Indeed - but that's the correct documented behaviour, even if not
>> > necessarily the ideal. There are various things you can do:
>> >
>> > a) Delete ./a.cmi as part of your build procedure. This isn't ideal,
>> > though, because you lose the type-checking against d/a.cmi
>> > b) Have an empty ./a.mli but never compile it - the compiler will then
>> > unify ./a.cmo against d/a.cmi. This isn't ideal because having a
>> > source file which you don't expect to compile will confuse dependency
>> > generators and automatic build rules.
>> > c) Implement a new option in the compiler driver which suppresses the
>> > automatic generation of .cmi files (e.g. ocamlc -c -I d -no-cmi a.ml)
>> 
>> d) Make the compiler skip generation of .cmi if it sees one in the -I
>>    directories?
>
> No - I think the use-case is too niche to justify breaking backwards
> compatibility. That's potentially a very subtle way to break someone
> else's existing build system. The existing behaviour is precisely
> documented in the manual (even if it's not necessarily the best
> approach).
>

Original post asked for either change of behavior or documentation, I
failed to find the precise documentation, care pointing out where
exactly things are described in the manual?

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