An equivalent of failOnAllWarnings

[NorfairKing]

It looks like there is no equivalent of failOnAllWarnings from nixpkgs.
I tried a bunch of variations of buildFlags = [ "-Wall" "-Werror" ] but there doesn't seem to be a buildFlags option.

[hamishmack]

These are ghc options. For stack projects these can be set in the stack.yaml file like this (where test-ghc-options is the name of the package).

Unfortunately while they can be set in cabal.project files as well (like this) we do not have a way to pick them up from there in haskell.nix yet.

You can set them in nix like this (works for cabal and stack projects).

[NorfairKing]

Alright! Now I just need to be able to set it for all local packages at once.

I'll have a look at #298 and #519 which seems to be a duplicate of this.