[Caml-list] Static linking with Mingw and dune

[Andreas Rossberg <rossberg@mpi-sws.org>]

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[Oops, forgot to check Reply-all.]


> Begin forwarded message:
> 
>> On 12. Dec 2024, at 18:31, Xavier Leroy <xavier.leroy@college-de-france.fr> wrote:
>> 
>> On Thu, Dec 12, 2024 at 8:46 AM Andreas Rossberg <rossberg@mpi-sws.org <mailto:rossberg@mpi-sws.org>> wrote:
>>> Good to know, thank you for the suggestions!
>>> 
>>> However, I’m afraid that hacking the compiler and tool chain for this purpose is not an option — that would require everybody else who wants to build the project to do the same, which is infeasible.
>>> 
>>> It’s a bit disappointing that there seems to be no easy solution for this problem. I would expect it to be a common pain point for folks using OCaml 5 to develop and publish application binaries for Windows. Or am I just alien?
>> 
>> OCaml's dependency on winpthreads will probably go away in the near future, see https://github.com/ocaml/ocaml/pull/13416 .
> 
> Ah, that’s good to know!
> 
>> But, more generally, static linking of C libraries is getting more and more difficult -- even from C, not just OCaml.  For example, under Linux, it's essentially impossible to statically link with the glibc C standard library; a musl-based distribution must be used if static linking is desired.  It looks as if the consensus was that static linking of libraries is a bad idea and must be prevented.  I don't think it is, but that's something way beyond OCaml's control.
> 
> Yeah, acknowledged. It’s sad IMO, as both static and dynamic linking have valid use cases, and ideally should be interchangeable mostly transparently. But maybe I’m having my ML modules hat on.
> 
> Cheers,
> /Andreas
> 
> 
>> Best,
>> 
>> - Xavier Leroy
>> 
>> 
>>  
>>> 
>>> Cheers,
>>> /Andreas
>>> 
>>> 
>>> > On 2. Dec 2024, at 09:25, Antonin Décimo <antonin.decimo@gmail.com <mailto:antonin.decimo@gmail.com>> wrote:
>>> > 
>>> >> Regarding OCaml 5.3/mingw64 you shouldn't need to have to do anything with libwinpthreads because it's only used for the msvc port, not the mingw one.
>>> > 
>>> > That is not quite exact, winpthreads is used with mingw-w64, but found
>>> > in the system installation, and linked to. It is vendored for the MSVC
>>> > port and we *statically* link into the runtime only the parts we're
>>> > interested in.
>>> > 
>>> > To statically link with winpthreads, I suggest you do all of it manually:
>>> > - clone winpthreads sources at https://github.com/mingw-w64/mingw-w64,
>>> > go to mingw-w64-libraries/winpthreads, and build a static version of
>>> > the library with your preferred toolchain;
>>> > 
>>> > - hack the OCaml compiler / Makefile to *not* use `-lpthreads`:
>>> >  https://github.com/ocaml/ocaml/blob/5a5eb481c7a9d0f039e3169aa8ed19c9b926e982/configure.ac#L2372-L2373
>>> >  Maybe it's just sufficient to set PTHREAD_LIBS when invoking
>>> > configure; however seeing this line makes me think that winpthreads is
>>> > already statically linked with the runtime.
>>> > 
>>> >     PTHREAD_LIBS="-l:libpthread.a $link_gcc_eh"]
>>> > 
>>> >  Haven't dug further.
>>> > 
>>> > -- Antonin


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