cabal 3.2 can't build happy-lib

[leonschoorl]

root@6116f1f2e872:~# cabal --version
cabal-install version 3.2.0.0
compiled using version 3.2.0.0 of the Cabal library 
root@6116f1f2e872:~# ghc --version
The Glorious Glasgow Haskell Compilation System, version 8.10.7
root@6116f1f2e872:~# cabal install happy --dry-run
Resolving dependencies...
Error:
    Dependency cycle between the following components: library
    In the package 'happy-lib-2.0.1'

root@6116f1f2e872:~# cabal-3.4.0.0 install happy --dry-run
Resolving dependencies...
Build profile: -w ghc-8.10.7 -O1
In order, the following would be built (use -v for more details):
 - happy-lib-2.0.1 (lib:grammar) (requires download & build)
 - happy-lib-2.0.1 (lib:tabular) (requires download & build)
 - happy-lib-2.0.1 (lib:frontend) (requires download & build)
 - happy-lib-2.0.1 (lib:backend-lalr) (requires download & build)
 - happy-lib-2.0.1 (lib:backend-glr) (requires download & build)
 - happy-lib-2.0.1 (lib) (requires download & build)
 - happy-2.0.1 (exe:happy) (requires download & build)
root@6116f1f2e872:~# 

So it's probably good to set cabal-version to 3.4

Although if I do that on a local copy, cabal 3.2 reports:

Errors encountered when parsing cabal file lib/happy-lib.cabal:

lib/happy-lib.cabal:0:0: error:
Unsupported cabal-version. See https://github.com/haskell/cabal/issues/4899.

I don't know, but I'm assuming that when cabal sees this on hackage then it will fallback to an earlier version.

[sgraf812]

Thanks. Indeed it sounds like the following cabal bug: haskell/cabal#6894, perhaps triggered by our use of multiple private library components.

Requiring cabal version 3.4 seems like the best solution because it gives a much clearer error message.

[sgraf812]

I just released version 2.0.2 on hackage and deprecated versions 2.0 and 2.0.1.