RFC: "Native -XCPP" Proposal

[Herbert Valerio Riedel]

On 2015-05-06 at 18:53:08 +0200, Howard B. Golden wrote:
> At the risk of antagonizing some (most? all?) of you, how about...
>
> -XCPP stands for the native CPP
> -XGNUCPP stands for GNU's GCC CPP
> -XClangCPP stands for Clang's CPP
> -XCPPHS stands for CPPHS

Assuming this was a serious suggestion, the benefit is that you could
clearly mark what CPP you want to develop against, but OTOH, we'd lose
backward compat w/ Haskell compilers only knowing about the old -XCPP
but not the other new variants of the language-pragma.

Moreover, there can now be packages that require clang-cpp, while others
require gcc-cpp, and I don't think it can be assumed that both are
available on every GHC installation. So it could cause packages to fail
compiling simply because the respective CPP-flavor is missing.  On the
bright side, this would maybe give us the opportunity to coin the new
term "CPP Hell" =)

Cheers,
  hvr