build failures when hiding non-visible imports

[John Lato]

Hello,

One of the issues I've noticed with ghc-7.6 is that a number of
packages fail due to problematic import statements.  For example, any
module which uses

> import Prelude hiding (catch)

now fails to build with the error

    Module `Prelude' does not export `catch'

Of course fixing this example is relatively straightforward, but that
isn't always the case.

Would it be reasonable to change ghc's behavior to treat this as a
warning instead of an error?

Cheers,
John L.