version information should include internal GHC version

[lspitzner]

> cabal haddock
cabal: Haddock's internal GHC version must match the configured GHC version.
The GHC version is 7.10.1 but haddock is using GHC version 7.8.4
> haddock --version
Haddock version 2.15.0.2, (c) Simon Marlow 2006
Ported to use the GHC API by David Waern 2006-2008

If the internal GHC version is important, it should be included in the version output. (If not, forward this issue to cabal please).

[dmcclean]

:+1:

[harpocrates]

The --ghc-version flag exists for this purpose (in fact, that is what Cabal uses).

$ haddock --version
Haddock version 2.17.3, (c) Simon Marlow 2006
Ported to use the GHC API by David Waern 2006-2008
$ haddock --ghc-version
8.0.2