[Hackage] #227: Cabal-install does not track down build-tools: dependencies?

[Hackage]

#227: Cabal-install does not track down build-tools: dependencies?
---------------------------------+------------------------------------------
  Reporter:  guest               |        Owner:         
      Type:  defect              |       Status:  new    
  Priority:  normal              |    Milestone:         
 Component:  cabal-install tool  |      Version:  1.2.3.0
  Severity:  normal              |     Keywords:         
Difficulty:  normal              |   Ghcversion:  6.8.2  
  Platform:                      |  
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 On #haskell, nelhage mentioned that one of the bugs he ran into while
 trying to install Yi-0.3 through cabal-install was an error which looked
 like this:

 <pre>
 Installing: /home/gwern/.cabal/lib/regex-posix-0.72.0.2/ghc-6.8.2/regex-
 posix-0.72.0.2/ghc-6.8.2
 Registering regex-posix-0.72.0.2...
 Reading package info from "dist/installed-pkg-config" ... done.
 Saving old package config file... done.
 Writing new package config file... done.
 'yi-0.3' is cached.
 [1 of 1] Compiling Main             ( Setup.hs, dist/setup/Main.o )
 Linking dist/setup/setup ...
 Configuring yi-0.3...
 setup: alex version >=2.0.1&&<3 is required but it could not be found.
 </pre>

 That is, the dependency on Alex (a version which satisfied >=2.0.1&&<3)
 was not met. Perfectly sensible as he did not have Alex installed.
 Puzzled, he did a 'cabal install alex', which worked, and then re-started.
 (I guess he had his GHC installed locally?).

 He and I were puzzled, because cabal-install is supposed/usually does
 track down dependencies. Is build-tools excluded for a reason, or was it
 just accidentally omitted from dependency-tracking? If the latter, I think
 this is a bit of a bug.

 (I use Cabal-1.2.3.0, btw, and the error message above was my reproduction
 of Nelhage's problem. I had to uninstall Alex from my system, but that did
 the trick, and reinstalling bypassed the issue just fine - which is why I
 hadn't seen it before.)

 --
 gwern

-- 
Ticket URL: <http://hackage.haskell.org/trac/hackage/ticket/227>
Hackage <http://haskell.org/cabal/>
Hackage: Cabal and related projects