How to use cohttp-lwt-unix on Windows 10 (cygwin)

[whoek]

THIS IS NOT A BUG REPORT BUT A QUESTION ON LIBRARY USAGE ON WINDOWS

Question on issue with cohttp-lwt-unix on Windows 10 (cygwin): I am (was) using cohttp-lwt-unix to pull data from a https API. After a recent failed opam upgrade, I had to re-install cohttp-lwt-unix and some other libraries, but now my program fails with following error message:

Fatal error: exception Failure("No SSL or TLS support compiled into Conduit")

I am using 4.12.0+mingw64c on Windows 10 (cygwin). Also tried re-installing cohttp-lwt-unix,tls,cohttp and some other libraries but no luck.

Observation on missing items:

This is ldd currently

C:\>ldd demo.exe
        ntdll.dll => /cygdrive/c/WINDOWS/SYSTEM32/ntdll.dll (0x7ff937cb0000)
        KERNEL32.DLL => /cygdrive/c/WINDOWS/System32/KERNEL32.DLL (0x7ff9368f0000)
        KERNELBASE.dll => /cygdrive/c/WINDOWS/System32/KERNELBASE.dll (0x7ff935440000)
        msvcrt.dll => /cygdrive/c/WINDOWS/System32/msvcrt.dll (0x7ff936dd0000)
        ADVAPI32.dll => /cygdrive/c/WINDOWS/System32/ADVAPI32.dll (0x7ff936330000)
        sechost.dll => /cygdrive/c/WINDOWS/System32/sechost.dll (0x7ff936160000)
        RPCRT4.dll => /cygdrive/c/WINDOWS/System32/RPCRT4.dll (0x7ff9369f0000)
        WS2_32.dll => /cygdrive/c/WINDOWS/System32/WS2_32.dll (0x7ff936460000)
        VERSION.dll => /cygdrive/c/WINDOWS/SYSTEM32/VERSION.dll (0x7ff92e160000)

This was results of ldd a few days ago when everything was working OK

C:\>ldd demo.exe
	ntdll.dll => /cygdrive/c/WINDOWS/SYSTEM32/ntdll.dll (0x7ffb45050000)
	KERNEL32.DLL => /cygdrive/c/WINDOWS/System32/KERNEL32.DLL (0x7ffb441e0000)
	KERNELBASE.dll => /cygdrive/c/WINDOWS/System32/KERNELBASE.dll (0x7ffb42bb0000)
	msvcrt.dll => /cygdrive/c/WINDOWS/System32/msvcrt.dll (0x7ffb44f70000)
	ADVAPI32.dll => /cygdrive/c/WINDOWS/System32/ADVAPI32.dll (0x7ffb44d90000)
	sechost.dll => /cygdrive/c/WINDOWS/System32/sechost.dll (0x7ffb44cc0000)
	RPCRT4.dll => /cygdrive/c/WINDOWS/System32/RPCRT4.dll (0x7ffb44e40000)
	bcrypt.dll => /cygdrive/c/WINDOWS/System32/bcrypt.dll (0x7ffb42e90000)
	CRYPT32.dll => /cygdrive/c/WINDOWS/System32/CRYPT32.dll (0x7ffb42950000)
	ucrtbase.dll => /cygdrive/c/WINDOWS/System32/ucrtbase.dll (0x7ffb42850000)
	WS2_32.dll => /cygdrive/c/WINDOWS/System32/WS2_32.dll (0x7ffb432c0000)
	VERSION.dll => /cygdrive/c/WINDOWS/SYSTEM32/VERSION.dll (0x7ffb37850000)

Note the following 3 are missing currently -- it is not helping me, but thought it might be of help.

	bcrypt.dll => /cygdrive/c/WINDOWS/System32/bcrypt.dll (0x7ffb42e90000)
	CRYPT32.dll => /cygdrive/c/WINDOWS/System32/CRYPT32.dll (0x7ffb42950000)
	ucrtbase.dll => /cygdrive/c/WINDOWS/System32/ucrtbase.dll (0x7ffb42850000)

Any idea on which opam library might be missing / what to do next.

A sample test program here: https://github.com/whoek/ocaml-https-demo

SIDE NOTE: What is good practice before running opam upgrade and loosing libraries if errors? Do I make a copy of my working opam switch before upgrading? (and how?)

Many Thanks
Willem

[avsm]

Could you try opam install tls-lwt and see if you get it working? There was a change in tls.0.16.0 to switch the subpackage needed for TLS support in Conduit into the new package, which is indeed confusing for end users of the package. Discussion on that is here mirage/ocaml-conduit#420

[whoek]

@avsm YES -- it worked - thank you very much for responding.