[Hackage] #132: Add "tools" field (like "extensions")

[Hackage]

#132: Add "tools" field (like "extensions")
------------------------------+---------------------------------------------
  Reporter:  guest            |        Owner:  ijones   
      Type:  enhancement      |       Status:  new      
  Priority:  high             |    Milestone:  Cabal-1.2
 Component:  Cabal            |      Version:  HEAD     
  Severity:  normal           |   Resolution:           
  Keywords:                   |   Ghcversion:  6.4.2    
Difficulty:  easy (<4 hours)  |     Platform:  Linux    
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Changes (by duncan):

  * difficulty:  normal => easy (<4 hours)
  * milestone:  => Cabal-1.2
  * version:  1.1.6 => HEAD

Comment:

 So I've added a "build-tools:" field. However I've added it to the top
 level part of the cabal package structure where really it should be part
 of the library and executable sections. I couldn't figure out how to do
 that though, I'm hoping Thomas will fix that for me :-)

 So it allows version ranges too, and it uses the Program infrastructure to
 check for these being satisfied. It rejects programs that are not known to
 Cabal (note that the known programs can be extended by via the hooks in a
 Setup.hs script).

 This does not address the question about pre-generated pre-processor
 output included in sdist tarballs.

 As for the cpp issue, the build-tools refers to a specific program, so
 it's not for the general notion of requiring C style pre-processing. So I
 think CPP is an extension, and ghc, cpp and cpphs are possible programs
 that cabal may choose to implement the CPP language extension. So in fact
 Cabal does not even know about the "cpp" program as it uses ghc or cpphs.

-- 
Ticket URL: <http://hackage.haskell.org/trac/hackage/ticket/132>
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