'source-repository' should not necessarily require 'cabal-version >= 1.6'

[andersk]

Distribution.PackageDescription.Check has this check:

    -- check use of "source-repository" section
  , checkVersion [1,6] (not (null (sourceRepos pkg))) $
      PackageDistInexcusable $
           "The 'source-repository' section is new in Cabal-1.6. "
        ++ "Unfortunately it messes up the parser in earlier Cabal versions "
        ++ "so you need to specify 'cabal-version: >= 1.6'."

However, I’ve found that Cabal 1.2 can successfully parse a cabal file with a 'source-repository' section (with a warning), _if_ that section is at the end of the file. Perhaps the check could be loosened to allow (and suggest) this?

[duncan]

I'm not convinced it is worth it. At the place we do the above check, it's already been parsed and we do not know where in the file the section appears.

[andersk]

This issue seems to have led to a regression in the extensible-extensions package:  http://hackage.haskell.org/trac/ghc/ticket/3931.

[duncan]

The extensible-extensions issue was solved by not requiring a later cabal version. It is not critical that packages designed for maximum backwards compatibility be able to specify source repos.

[elga]

*  virgin mobile