Re: [Haskell-cafe] How to set a GHC option for a single module and a specific version of GHC?

On Sat, Jun 5, 2010 at 3:28 AM, Bernie Pope wrote:

Hi,

I'm looking for a way to set a GHC compile option on a specific module (not every module in the program) but only for a specific version of GHC. Ideally within the confines of cabal, and in a portable way.

GHC provides the OPTIONS_GHC pragma, but it does not appear to provide a way for the pragma to fire for specific versions of GHC. Also, I can't use an #ifdef trick because "File-header pragmas are read once only, before pre-processing the file (e.g. with cpp)."

Cabal provides conditional statements and a way to check the version of GHC, but I can't see a way to get it to only use certain compiler options for a particular module.

In summary, what I really want is a modified version of the OPTIONS_GHC pragma:

  {-# OPTIONS_GHC ==6.12.1 ... #-}

or a way to tell cabal to use certain compiler options for a particular module under certain conditions.

A not-great work-around is to have this one file in a separate source directory, and then use a different extra source directory based on the GHC version (by using an if statement in the package description). Antoine