Breakage with ghc-6.10

Ashley Yakeley ashley at
Fri Oct 10 14:08:34 EDT 2008

On Fri, 2008-10-10 at 09:08 -0700, Duncan Coutts wrote:
> Data/Time/Clock/CTimeval.hs:1:11:
>     Warning: -ffi is deprecated: use -XForeignFunctionInterface or
> pragma {-# LANGUAGE ForeignFunctionInterface#-} instead
> <no location info>:
> Failing due to -Werror.
> NOOOOooooooooooooooooooo!!!!!!
> This is the reason that hackage now rejects the use of -Werror in
> released packages. It causes unnecessary breakage when new compilers
> add new warnings.

Warnings in a build process should be fixed, not ignored (and, I would
say, fixed by whoever introduced the warning or otherwise broke the

Hackage, on the other hand, is right to reject -Werror in .cabal files,
as there the build is really part of the install process and should be
as lenient as possible. I pass --ghc-options="-Wall -Werror" to cabal in
a Makefile in most of my projects, so that my development build process
is strict.

Ashley Yakeley

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