[nix-local-build] Need new-style clean

[ezyang]

A few bugs:

1. "cabal clean" doesn't clean dist-newtyle. Maybe need a "cabal new-clean"?
2. cabal clean obviously isn't going to respect projects

CC @dcoutts

[dcoutts]

What should it clean do you think? All the local packages and cached info? Or just one package, or ?

[ezyang]

Current cabal clean just cleans one package (e.g. that happens if you use it in a sandbox?) so that's my inclination. Though I'm not sure.

[hvr]

Fwiw, I'd expect cabal new-clean to remove the dist-newstyle/ which may contain all sorts of executables and local artifacts (i.e. non-cabal-store artifacts)

[lspitzner]

note that custom Setup.hs gets compiled into $PACKAGE/dist/.. even with new-build. so new-build clean might need to

packages `forM_` \path -> rm -rf (path</>dist)

as well. (sorry for the haskell/bash mixture, it is horrible.)

[ezyang]

Putting this low priority because the workaround is really simple (just delete dist-newstyle yourself.)

[gbaz]

Its irritating to discover the workaround -- this just hit me and I ended up here :-)