How to force -fPIC on package builds?

[Dominick Samperi]

Thanks for looking into this Mathieu. I have been using this hsc2hs
flag all along, and it has enabled me to build inline-r, but the build
of H fails (using ghc-8.0.1). As you mention in your issue tracker,
the new twist is to add ghc-options: -dynamic to the cabal file for H
(and for any binary that links to inline-r).

BTW, how can I compare my results with yours if all I know is that you
have used "a docker container"? Wouldn't I need to know what
repository and snapshot you are using?

On Sun, Aug 14, 2016 at 2:55 PM, Boespflug, Mathieu <m at tweag.io> wrote:
> I was able to reproduce in a docker container and tracked down the source of
> the issue: https://github.com/tweag/HaskellR/issues/257
>
> The executive summary is that if Cabal is asking hsc2hs to link to a dynamic
> library, then it should pass --cflag=-fPIC to hsc2hs. Otherwise hsc2hs might
> fail, because then it might be impossible to link the temporary object files
> that it creates with the shared library.
>
> A workaround is to set "cc-options: -fPIC" in the .cabal file. But in my
> mind this is probably a Cabal bug.
>
> --
> Mathieu Boespflug
> Founder at http://tweag.io.
>
> On 14 August 2016 at 06:12, Dominick Samperi <djsamperi at gmail.com> wrote:
>>
>> I should add that H builds and runs nicely under Windows and MacOS
>> (using ghc 8.0.1), so this is indeed a Fedora Linux issue.
>>
>> On Sat, Aug 13, 2016 at 10:22 AM, Dominick Samperi <djsamperi at gmail.com>
>> wrote:
>> > Hello Mathieu,
>> >
>> > I'm using Fedora 23. The default Haskell Platform here provides ghc
>> > 7.8.4, and this seems to have even more problems. Thus I have been
>> > trying to use ghc 8.0.1 compiled from source. I think the red herring
>> > bit may apply to 32 bit builds, but I am attempting a 64 bit build.
>> > The problem may be related to the way modules are randomly relocated
>> > for security reasons, Fedora security policies, and confusion/bugs in
>> > the linker(s).
>> >
>> > Cheers,
>> > Dominick
>> >
>> >
>> > On Sat, Aug 13, 2016 at 7:43 AM, Boespflug, Mathieu <m at tweag.io> wrote:
>> >> Hi Dominick,
>> >>
>> >> which version of Fedora Linux are you on? The -fPIC message from the
>> >> linker
>> >> may well be a red herring. AFAIR generating PIC is the default in GHC,
>> >> at
>> >> least for dynamic libraries.
>> >>
>> >> Best,
>> >>
>> >> --
>> >> Mathieu Boespflug
>> >> Founder at http://tweag.io.
>> >>
>> >> On 13 August 2016 at 05:55, Dominick Samperi <djsamperi at gmail.com>
>> >> wrote:
>> >>>
>> >>> Hello,
>> >>>
>> >>> I am getting relocation errors when building an executable
>> >>> (specifically, the "H"
>> >>> executable -- part of haskellR) under Fedora Linux, and the message
>> >>> says
>> >>> to
>> >>> "recompile with -fPIC".
>> >>>
>> >>> The FAQ associated with H suggests that I switch to the gold linker
>> >>> (ld.gold) due to bugs in the default linker (ld.bfd), but this only
>> >>> changes the wording of the relocation error messages.
>> >>>
>> >>> I have tried several strategies for satisfying the -fPIC requirement:
>> >>> 1. In cabal files I insert cc-options: and ghc-options: lines
>> >>> including
>> >>> -fPIC
>> >>> 2. To the 'cabal install' command line I add:
>> >>>     --ghc-option=-fPIC --hsc2hs-option=-cflag=-fPIC
>> >>> 3. When building ghc 8.0.1 from source I modify config.mk by
>> >>> including:
>> >>>    CONF_CC_OPTS += -fPIC
>> >>>    SRC_HSC2HS_OPTS += --cflag=-fPIC
>> >>>    CONF_CC_OPTS_STAGE0 = -fno-stack-protector -fPIC
>> >>>    [same for STAGE1 and STAGE2]
>> >>>
>> >>> All of this doesn't fix the problem, and the error messages still say
>> >>> "recompile with -fPIC".
>> >>>
>> >>> This may be a bug, but I'm not sure where. Any ideas?
>> >>>
>> >>> Thanks,
>> >>> Dominick
>> >>> _______________________________________________
>> >>> ghc-devs mailing list
>> >>> ghc-devs at haskell.org
>> >>> http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs
>> >>
>> >>
>
>