[Hackage] #931: Support building source trees with many packages

[Hackage]

#931: Support building source trees with many packages
---------------------------------+------------------------------------------
  Reporter:  tibbe               |        Owner:          
      Type:  enhancement         |       Status:  new     
  Priority:  normal              |    Milestone:          
 Component:  cabal-install tool  |      Version:  1.10.2.0
  Severity:  normal              |     Keywords:          
Difficulty:  unknown             |   Ghcversion:          
  Platform:                      |  
---------------------------------+------------------------------------------
 A not uncommon use case is building a package against a set of
 dependencies that exist in (unreleased) source form. For example, given
 two packages:

 {{{
 $ ls
 hashable
 unordered-containers
 }}}

 I'd like to be able to

 {{{
 $ cd unordered-containers
 cabal build --root=..
 }}}

 Cabal should then recursively traverse directories from `--root`, looking
 for .cabal files to use when fulfilling dependencies (i.e. in this case
 it'd find `hashable`.) Those dependencies should also be marked as
 preferred to any Hackage versions of the package with the same version
 number.

 It'd also be convenient to add several `--root` flags, so one can specify
 specific packages to use in source form (without using e.g. the user's
 complete `~/src` directory.)

 {{{
 $ cd unordered-containers
 cabal build --root=../hashable --root=../text
 }}}

-- 
Ticket URL: <http://hackage.haskell.org/trac/hackage/ticket/931>
Hackage <http://haskell.org/cabal/>
Hackage: Cabal and related projects