RE: [Caml-list] ocamlbuild on cygwin

[David Allsopp <dra-news@metastack.com>]

Gergely Szilvasy wrote:
> I'm trying to get as much of the ocaml/opam stack working on cygwin as possible
> (as if there wasn't enough pain and suffering in the world already).

That's some pain! Not that it affects the bug you describe, but do you have a specific reason to use the Cygwin build, and not the MinGW/MSVC ports?

> Opam compiles without any issues, and I can switch to (let's say) 4.02.1 cleanly.
>
> However, ocamlbuild fails for me in "opam install react" with the following error:
>
> "Failure: ocamlfind not found on path, but -no-ocamlfind not used."
>
> (Note that react is required by utop, for example, so it's a pretty basic requirement.)
>
> This is where the exception is thrown:
>
> https://github.com/ocaml/ocaml/blob/trunk/ocamlbuild/options.ml#L295
>
> It is the result of Command.search_in_path not finding ocamlfind:
>
> https://github.com/ocaml/ocaml/blob/trunk/ocamlbuild/command.ml#L130
>
> Which appears to be caused by file_or_exe_exists not appending ".exe" to the filename when Sys.os_type =
> "Cygwin" (which is what I see as os_type when compiling on cygwin):
>
> https://github.com/ocaml/ocaml/blob/trunk/ocamlbuild/command.ml#L128

This test is weak, and the behaviour is a bug (=> raise a report in Mantis). ocamlbuild should query the Config module from the compiler libs and do one of the following:

1. Add an extra value ext_exe : string which would be ".exe" for Windows builds (*including* Cygwin) and "" for everything else.
2. Instead of detecting Sys.os_type = "Cygwin", instead do Filename.check_suffix Config.default_executable_name ".exe" (I can't check on this machine, but I'm fairly sure that ocamlc -config will shows the normal camlprog.exe for default_executable_name?)

> In any case, I'm pretty sure this fairly simple bug is not a (very) recent 
> regression, so I'm wondering if anybody cares about opam/ocaml on cygwin? 
> I'd really like to use opam, because it looks to me this is the community's 
> preferred way of distributing bits. My question is, really, what is the 
> status of ocaml/opam on cygwin? Is there an alternative environment for 
> Windows + opam that works better? (I know about wodi, but I'd prefer 
> opam.) Is it worth spending time fixing these issues on cygwin?

Cygwin is a targeted platform, so bugs in it are important - but I think that the small number of Windows OCaml users use the MinGW or MSVC ports so they may take a while to be noticed!

Opam status on Windows is partially recorded in https://github.com/ocaml/opam/issues/246.

HTH,


David