Need a way to force a package to be re-installed

[bos]

(Imported from Trac #301, reported by guest on 2008-06-20)

cabal-install currently offers no way of reinstalling a version of a package which is already installed. If one has been messing around with libraries behind Cabal's back, this might be useful, if for no other reason than to assuage one's worries regarding link errors.

Ideally a flag --force or whatever could be given to cabal upgrade and cabal install, which would make bypass the check for whether the package exists.

[bos]

(Imported comment by @dcoutts on 2008-06-20)

See also #297. The solution is very similar. Just hide the installed package from the dep resolver.

[bos]

(Imported comment by @dcoutts on 2008-06-20)

Thu Aug 14 19:34:45 BST 2008  Duncan Coutts <[email protected]>
  * Add cabal install --reinstall flag
  to force reinstall of package where we have the exact same
  version already installed. Ordinarily we would say that
  there is nothing to do as the exact same package version
  is already installed. There are some cases where you might
  want to do this, eg to rebuild with different compiler
  options, or adding/removing components (since we do not
  track those indifidually yet, eg docs, profiling libs).

Also, the message when something is already installed and thus will not be re-installed is improved:

$ cabal install something
Resolving dependencies...
No packages to be installed. All the requested packages
are already installed. If you want to reinstall anyway
then use the --reinstall flag.