Oddity with 'cabal install' in GHC 7.4.1

Andres Löh andres.loeh at googlemail.com
Sun Feb 5 06:51:14 CET 2012

Hi Conal.

On Sun, Feb 5, 2012 at 12:36 AM, Conal Elliott <conal at conal.net> wrote:
> Since upgrading to 7.4.1, if I 'cabal install' successfully and then 'cabal
> install' a second time without first doing a 'ghc-pkg unregister
> <package-name>', I get the following complaint:
> [...]

The warning is intended to prevent you from breaking your system
without knowing that you know that you're running a potentially
dangerous cabal invocation.

The --force-reinstalls flag should always make it build. If it
doesn't, it's a bug.

In addition, I'm planning to make the warning a little bit less
aggressive before the release.

> The only path I've found so far that's willing to rebuild or even say
> nothing needs rebuilding (when nothing does) is to 'ghc-pkg unregister' and
> then 'cabal install' again. I'm getting the same behavior on Red Hat 5 and
> Mac OS 10.6.8, both compiled from sources.

I'd be surprised if the OS matters. But as I said, I've not yet
encountered a situation where it wouldn't build given


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