Bug#1068586: ghc: Broken on arm{el,hf} because of time_t transition

[Ilias Tsitsimpis]

Package: ghc
Version: 9.4.7-3
Severity: grave
Justification: renders package unusable

I recently uploaded a new version of GHC to unstable, in order to fix
#1068179. As a result, GHC got rebuilt taking into account the new size
for time_t on arm{el,hf}. This is evident from the build logs, where
we now see:

  https://buildd.debian.org/status/fetch.php?pkg=ghc&arch=armel&ver=9.4.7-4&stamp=1712410679&raw=0

  checking Haskell type for time_t... Int64

whereas previously we had:

  https://buildd.debian.org/status/fetch.php?pkg=ghc&arch=armel&ver=9.4.7-3&stamp=1708366014&raw=0

  checking Haskell type for time_t... Int32


After this change, a number of Haskell packages have started to FTBFS:

* https://buildd.debian.org/status/fetch.php?pkg=haskell-filestore&arch=armel&ver=0.6.5-3%2Bb2&stamp=1712457355&raw=0
* https://buildd.debian.org/status/fetch.php?pkg=haskell-fold-debounce&arch=armel&ver=0.2.0.11-1%2Bb2&stamp=1712466208&raw=0
* https://buildd.debian.org/status/fetch.php?pkg=haskell-hourglass&arch=armel&ver=0.2.12-5%2Bb2&stamp=1712462130&raw=0

Looking into this, I see that (at least) the getPOSIXTime method is
broken on arm{el,hf}. Compiling the following program on armel:

  $ cat Time.hs
  import Data.Time.Clock.POSIX

  main = do
    t <- getPOSIXTime
    print t

  $ ghc -o time Time.hs
  $ ./time
  3590884976642664859s

whereas on an amd64 system it returns:

  $ ./time
  1712499127.06215219s

This bug blocks the time_t transition (#1036884).

-- 
Ilias