Bug#1010025: ghc: Haddock fails with internal error when calculating transitive dependencies

[Scott Talbert]

On Sat, 23 Apr 2022, Felix Lechner wrote:

> Hi Scott,
>
>> Warning: The documentation for the following packages are not installed. No
>> links will be generated to these packages: dlist-0.8.0.8, hashable-1.3.0.0,
>> transformers-compat-0.6.5
>
> Can you please try to see if the error goes away when those
> prerequisites are made available?
>
> I believe they are in:
>
>    libghc-dlist-doc
>    libghc-hashable-doc
>    libghc-transformers-compat-doc

Adding those BD's makes the warning about missing links go away, but 
doesn't fix the internal error.  There's an upstream fix that seems to fix 
the error, though.  I've created a merge request[1] with a cherry-pick of 
the upstream fix.  I sent a MR since it's a core package and I'm new here, 
but it seems like a fairly straighforward fix.  Let me know if anyone has 
any objections.

Thanks,
Scott

[1] https://salsa.debian.org/haskell-team/DHG_packages/-/merge_requests/18