compiler directive of cabal-install's config file is case sensitive

[bos]

(Imported from Trac #379, reported by phigley on 2008-10-22)

Using cabal-install 0.6.0 (and 1.6.0.1 of the Cabal library) the following line fails to parse in the config file (in ~/.cabal/config) :

compiler: GHC

which generates the following error :
Warning: Error parsing config file /Users/peterhigley/.cabal/config:1: "GHC"
Warning: Using default configuration.

But changing it to this resolves the problem :

compiler: ghc

My config file was auto-generated from an older cabal-install.

This is easiest to reproduce by running "cabal update".

I am reproing on a Mac, but an e-mail was sent to haskell-cafe from a Windows user as well.

[bos]

(Imported comment by @dcoutts on 2008-10-22)

This is a more tricky problem than it looks. The reason is we're now parsing the config file by converting the command line parser. It has flags for --ghc, --hugs etc and is case sensitive. Really we'd like a config field flag parsed using the Text instance for CompilerFlavor because that is not case sensitive.

Doing this properly involves rewriting the command line option / config file field description subsystem.

[bos]

(Imported comment by @dcoutts on 2009-01-12)

Fixed with a bit of a hack:

Fri Jan 16 00:28:51 GMT 2009  Duncan Coutts <[email protected]>
  * Parse compiler field from old config files correctly
  Really old versions of cabal-install generated a default config
  containing "compiler: GHC". Sadly the new way we generate the
  config file parser from the command line parser means we end up
  with a case-sensitive parser as it only matches the exact
  command line flags. So we hack it and add in a traditional
  parser for that field only. Really the command line and config
  file infrastructure needs rewriting again. Sigh.