Problems building cabal-install?

[Viktor Dukhovni]

I am having a rather unexpected difficulty building older versions of
cabal-install.  The invariably run into conflicts between "Cabal" and
"Cabal-syntax".

The latter shows up as a dependency of "Cabal" on hackage, but not
in the upstream Git repo.  Is there is there some sort of problem
with the hackage metadata for Cabal 3.0, 3.2, 3.4, ...

It is odd for these to have "Cabal-syntax 3.10.*" as a dependency, with
conflicting definitions.

-- 
    Viktor.