Oddity with 'cabal install' in GHC 7.4.1

Conal Elliott conal at conal.net
Sun Feb 5 19:48:11 CET 2012

On Sun, Feb 5, 2012 at 12:43 AM, Andres Löh <andres.loeh at googlemail.com>wrote:

> Hi Conal.
> > Thanks for the reply! Note that I get this message even running 'cabal
> > install' a second time after changing nothing. Is that scenario an
> example
> > of what you mean by a "potentially dangerous cabal invocation"?
> The check currently is entirely ad-hoc. Any reinstallation of an
> existing package triggers the warning. There's no hash comparison.

I'm confused. Isn't package re-installation an extremely common thing in
cabal while developing software? Do you cope by habitually adding
--force-reinstall during development? Perhaps that habit is the piece
missing from my mental picture.

> I've been
> > unable to avoid this error message by any other means that (a) 'ghc-pkg
> > unregister <package>' or (b) '--force-reinstall'. So far,
> '--solver=modular'
> > hasn't helped. So I'm hoping for something less aggressive. In
> particular,
> > in case nothing has changed, I want 'cabal install' to succeed (exit
> code 0)
> > so that my automated build & install & release processes will continue
> > rather than get stopped.
> The message appears, but building should work, with --force-reinstall
> and no --dry-run. Can you confirm that you've tried that?
> Cheers,
>  Andres

Yes, building does work for me with --force-reinstall.

-- Conal
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