Re: Static linking with Mingw and dune

On Thu, Dec 12, 2024 at 8:46 AM Andreas Rossberg <[email protected]>
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 .

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.

Best,

- Xavier Leroy




>
> Cheers,
> /Andreas
>
>
> > On 2. Dec 2024, at 09:25, Antonin Décimo <[email protected]>
> 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
>
>