Different behavior in ghci 7.8.3 vs 7.10.1?

[Dominick Samperi]

It turns out the problem was due to a very old Setup.hs that I was
working with. After replacing it with the version recommended by the
latest cabal docs the undefined reference issues disappeared. Sorry!
I also added 'buildable: True' to the buildinfo file, following the latest docs.

On Sat, Jun 27, 2015 at 2:53 PM, Dominick Samperi <djsamperi at gmail.com> wrote:
> After much trial-and-error and web searching I found a work-around for
> ghci 7.10.1.
>
> It appears that BOTH extra-libraries and extra-lib-dirs must be
> specified in the cabal file. Previously the link parameters were
> specified using a <pkgname>.buildinfo file. It appears that with ghci
> 7.10.1 this information is no longer used? Specifically, the
> ld-options setting in that file is ignored.
>
> This work-around is not satisfactory because I do not want to
> hard-code the path to the exra lib in the cabal file for obvious
> reasons.
>
> It appears that some changes were made recently to the way cabal
> handles external linkage, and this is probably related to the problems
> reported here.
>
> On Sat, Jun 27, 2015 at 9:18 AM, Dominick Samperi <djsamperi at gmail.com> wrote:
>> In case this is not obvious, I should also note that this is a ghci
>> problem. When
>> compiled using ghc 7.10.1 there are no probelms with unresolved references.
>>
>> On Sat, Jun 27, 2015 at 9:07 AM, Dominick Samperi <djsamperi at gmail.com> wrote:
>>> I've attached the output of ghc --info. Will have to work on
>>> crafting a small example...
>>>
>>> On Sat, Jun 27, 2015 at 8:16 AM, Sergei Trofimovich <slyich at gmail.com> wrote:
>>>> On Sat, 27 Jun 2015 07:59:33 -0400
>>>> Dominick Samperi <djsamperi at gmail.com> wrote:
>>>>
>>>>> To test ghci 7.10.1 I compiled from source and simply placed the
>>>>> resulting bin in my PATH. Perhaps this is not enough?
>>>>
>>>> Sounds right. What does 'ghc --info' show?
>>>>
>>>>> On the second suggestion, I tried ldd and found that the undefined
>>>>> symbol is flagged 'B' in the nm output (.bss section).
>>>>>
>>>>> This symbol is defined in the shared library, and the output of ghc
>>>>> -v2 shows that this shared library is
>>>>> linked without problems on startup of ghci. When the Haskell/FFI
>>>>> function is run the symbol is undefined.
>>>>
>>>> Can you craft a complete small example with a build script that shows the error?
>>>>
>>>> --
>>>>
>>>>   Sergei