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

Tue Jun 6 12:32:45 UTC 2017

On 6 June 2017 at 21:13, Henk-Jan van Tuyl <hjgtuyl at chello.nl> wrote:
>
> You are right, versionBranch is from originally from base, but you are
> missing the point:
> package wxc compiles perfectly the first time, but, without anything being
> changed, does not compile the second time. By the way, I am using a cabal
> sandbox and as I said earlier, I am using a GHC release candidate.

And in that release candidate, does the version of base have
versionBranch in it?

My guess is that a new version of Cabal is being used the second time,
which is compiled against the base that comes with that RC which is
missing versionBranch.

(But since I don't have any GHC RC's I can't check it myself.)

>
> Regards,
> Henk-Jan van Tuyl
>
>
>
> On Tue, 06 Jun 2017 00:33:40 +0200, Ivan Lazar Miljenovic
> <ivan.miljenovic at gmail.com> wrote:
>
>> 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