Bug#1014628: FWD: Re: git-annex arm 32-bit builds

[Joey Hess]

I was looking at this bug the other day trying to determine why
git-annex was not in testing, and did not realize it was due to this
dbus issue. My mail below digs into it, if the issue is still
happening.

----- Forwarded message from Joey Hess <id at joeyh.name> -----

Date: Mon, 23 May 2022 12:48:21 -0400
From: Joey Hess <id at joeyh.name>
To: Sean Whitton <spwhitton at spwhitton.name>
Subject: Re: git-annex arm 32-bit builds

Sean Whitton wrote:
> git-annex is failing on Debian's autobuilders for armel and armhf.  It
> looks like an actual type error rather than the linker failing or
> something like that \o/
> 
> Would you be able to take a look, please?
> 
> https://buildd.debian.org/status/fetch.php?pkg=git-annex&arch=armel&ver=10.20220504-1&stamp=1652058911&raw=0

What fun.. addMatch comes from libghc-dbus-dev, and has type

addMatch ::
  Client
  -> MatchRule
  -> (DBus.Internal.Message.Signal -> IO ())
  -> IO SignalHandler
  	-- Defined in ‘DBus.Client’

I have verified in an armel (testing) chroot that it has that type. FWIW,
git-annex is building successfully for me in that chroot. That has
the identical package version 1.2.16-1+b1 that the autobuild log has.

Somehow, the autobuilder is seeing a different type for it despite the same
version of the same package being installed. The type seems to be :: ByteString.

I also looked at the source of the haskell package and it does not have any
conditional compilation or other way for addMatch to have that type, that
I can see.

This seems to point to the autobuilder having some manually hacked up version
of the haskell library installed on it that somehow overrides the package.
Or, ghc is somehow getting massively confused and is finding the wrong symbol
or something like that.

It would be interesting, I think to find out what is in that ByteString!
I suppose you could upload a package with something like this in its rules:

ghc -e 'import DBus.Client' -e 'print DBus.Client.addMatch' || true

-- 
see shy jo



----- End forwarded message -----
-- 
see shy jo
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