Bug#968066: haskell-hgettext: autopkgtest fails with newer version of ghc

[Paul Gevers]

Source: haskell-hgettext
Version: 0.1.31.0-5
Severity: serious
X-Debbugs-CC: debian-ci at lists.debian.org, ghc at packages.debian.org
Tags: sid bullseye
User: debian-ci at lists.debian.org
Usertags: needs-update
Control: affects -1 src:ghc

Dear maintainer(s),

With a recent upload of ghc the autopkgtest of haskell-hgettext fails in
testing when that autopkgtest is run with the binary packages of ghc
from unstable. It passes when run with only packages from testing. In
tabular form:

                       pass            fail
ghc                    from testing    8.8.3-3
haskell-hgettext       from testing    0.1.31.0-5
versioned deps [0]     from testing    from unstable
all others             from testing    from testing

I copied some of the output at the bottom of this report. It seems there
is some versioned dependency missing somewhere, either in the test
definition or in package itself, or something really breaks
haskell-hgettext in testing and doesn't declare it. If I read the error
correctly and understand a tiny bit of the haskell packaging, something
should prevent mix and match of packages build with different versions
of ghc.

Currently this regression is blocking the migration of ghc to testing
[1]. Of course, ghc shouldn't just break your autopkgtest (or even
worse, your package), but it seems to me that the change in ghc was
intended and your package needs to update to the new situation.

If this is a real problem in your package (and not only in your
autopkgtest), the right binary package(s) from ghc should really add a
versioned Breaks on the unfixed version of (one of your) package(s).
Note: the Breaks is nice even if the issue is only in the autopkgtest as
it helps the migration software to figure out the right versions to
combine in the tests.

More information about this bug and the reason for filing it can be found on
https://wiki.debian.org/ContinuousIntegration/RegressionEmailInformation

Paul

[0] You can see what packages were added from the second line of the log
file quoted below. The migration software adds source package from
unstable to the list if they are needed to install packages from
ghc/8.8.3-3. I.e. due to versioned dependencies or breaks/conflicts.
[1] https://qa.debian.org/excuses.php?package=ghc

https://ci.debian.net/data/autopkgtest/testing/amd64/h/haskell-hgettext/6551760/log.gz

autopkgtest [14:11:27]: test cabal-install-compatibility:
[-----------------------
Warning: No remote package servers have been specified. Usually you
would have
one specified in the config file.
Resolving dependencies...
cabal: Could not resolve dependencies:
[__0] trying: example-0.1.0 (user goal)
[__1] next goal: example:setup.Cabal (dependency of example)
[__1] rejecting: example:setup.Cabal-3.0.1.0/installed-3.0... (conflict:
example => example:setup.Cabal>=1.8 && <1.25)
[__1] fail (backjumping, conflict set: example, example:setup.Cabal)
After searching the rest of the dependency tree exhaustively, these were the
goals I've had most trouble fulfilling: example, example:setup.Cabal

autopkgtest [14:11:28]: test cabal-install-compatibility:
-----------------------]

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