[Haskell-cafe] Bug in GHC or cabal-install?

[Ivan Lazar Miljenovic]

On 6 June 2017 at 07:55, Henk-Jan van Tuyl <b.vantuyl1 at upcmail.nl> wrote:
>
> wxc/setup.hs uses versionBranch from Cabal[0]; the function versionBranch is
> not in Cabal 2, that is why I added "Cabal < 2" to wxc.cabal. When
> installing wxc the first time, the right version of Cabal is picked, when
> "cabal install" is invoked a second time, GHC tries to compile wxc/setup.hs
> again, but with the wrong version of Cabal (note: the release candidate of
> GHC comes with Cabal 2)
>
> [0]
> https://hackage.haskell.org/package/Cabal-1.24.2.0/docs/Distribution-Make.html#v:versionBranch

If you look at the source for this module, you'll see that it isn't
defined in there; it's actually from Data.Version in base.

>
>
>
> On Mon, 05 Jun 2017 04:58:05 +0200, Ivan Lazar Miljenovic
> <ivan.miljenovic at gmail.com> wrote:
>
>> I don't think it's a problem with Cabal, but the version of base going
>> by the error: versionBranch is from base, and that error message is
>> talking about compiling the setup.hs from wxc.
>>
>> On 5 June 2017 at 12:03, Henk-Jan van Tuyl <b.vantuyl1 at upcmail.nl> wrote:
>>>
>>>
>>> The strange thing is, that the right version of Cabal is picked, the
>>> first
>>> time wxc is compiled. But when invoking cabal-install the second time,
>>> the
>>> setup-depends section seems to be ignored (or at least the Cabal < 2
>>> part).
>>> This does not happen with GHC 8.0.2
>>>
>>> (By the way, cabal-install tries to compile setup.hs again, even though
>>> nothing has changed.)
>>>
>>> Regards,
>>> Henk-Jan van Tuyl
>>>
>>>
>>>
>>> On Sun, 04 Jun 2017 13:39:17 +0200, Ivan Lazar Miljenovic
>>> <ivan.miljenovic at gmail.com> wrote:
>>>
>>>> This is from a limitation/bug with Cabal-the-library, in that there
>>>> are typically no dependency checks for custom Setup.[l]hs
>>>> configurations.
>>>>
>>>> wxc has such a custom one:
>>>> http://hackage.haskell.org/package/wxc-0.92.3.0/src/Setup.hs
>>>>
>>>> versionBranch is from Data.Version in base, and it appears that the in
>>>> this GHC pre-release there's been a change in base that removed this
>>>> function.
>>>>
>>>> On 4 June 2017 at 19:45, Henk-Jan van Tuyl <hjgtuyl at chello.nl> wrote:
>>>>>
>>>>>
>>>>>
>>>>> L.S.,
>>>>>
>>>>> I am trying the prerelease of GHC, version 8.2.0.20170507
>>>>>
>>>>> I adapted wxHaskell to the new packages that come with the new GHC and
>>>>> it
>>>>> compiles now, but only the first time. If I compile it a second time,
>>>>> even
>>>>> if nothing has changed, the information from the custom-setup section
>>>>> of
>>>>> the wxc.cabal file seems to be forgotten. This section looks like this:
>>>>>
>>>>> custom-setup
>>>>>   setup-depends:
>>>>>     base,
>>>>>     Cabal < 2,
>>>>>     containers,
>>>>>     bytestring,
>>>>>     split,
>>>>>     process,
>>>>>     directory,
>>>>>     filepath
>>>>> (I am using cabal-install 1.24.0.2)
>>>>>
>>>>> Output from the second time I try to install wxHaskell:
>>>>>
>>>>>> cabal install --force-reinstalls --reinstall wxdirect wxc wxcore wx
>>>>>
>>>>>
>>>>>
>>>>> [1 of 1] Compiling Main             (
>>>>> X:\Temp\wxHaskell\wxcore\dist\setup\setup.hs,
>>>>> X:\Temp\wxHaskell\wxcore\dist\setup\Main.o )
>>>>> Linking X:\Temp\wxHaskell\wxcore\dist\setup\setup.exe ...
>>>>> [1 of 1] Compiling Main             (
>>>>> X:\Temp\wxHaskell\wxc\dist\setup\setup.hs,
>>>>> X:\Temp\wxHaskell\wxc\dist\setup\Main.o )
>>>>>
>>>>> X:\Temp\wxHaskell\wxc\dist\setup\setup.hs:505:61: error:
>>>>>                       Variable not in scope: versionBranch :: Version
>>>>> ->
>>>>> [a0]
>>>>>                       |
>>>>> 505 |           full_ver = (concat . intersperse "." . map show .
>>>>> versionBranch) ver
>>>>>                       |
>>>>> ^^^^^^^^^^^^^
>>>>>
>>>>> This error message indicates that the wrong version of Cabal (2.0) is
>>>>> used
>>>>> to compile the wxcore setup.hs
>>>>> It looks like a cabal-install bug, but this does not happen when I
>>>>> use GHC 8.0.2; should I write a GHC bug ticket?
>>>>>
>>>>> Regards,
>>>>> Henk-Jan van Tuyl
>
>
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> --



-- 
Ivan Lazar Miljenovic
Ivan.Miljenovic at gmail.com
http://IvanMiljenovic.wordpress.com