id,summary,reporter,owner,description,type,status,priority,milestone,component,version,severity,resolution,keywords,cc,difficulty,ghcversion,platform
227,cabal-install doesn't consider build-tools as dependencies,guest,duncan,"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
",defect,assigned,normal,cabal-install-0.16,cabal-install tool,1.2.3.0,normal,,dependencies build tools,kazuya@… ezyang@… conrad@…,hard (< 1 day),6.12.3,