cabal-to-nix doesn't respect build-tool-depends field

[eamsden]

Cabal has a field build-tool-depends: (see the cabal user guide: https://www.haskell.org/cabal/users-guide/developing-packages.html#pkg-field-build-tool-depends) which specifies Haskell executables needed at build-time. For instance, many test suites using hspec rely on hspec-discover, and should have a stanza:

test-suite spec
  ...
  build-tool-depends: hspec:hspec-discover

cabal-to-nix should generate dependencies on the specified executable component for components with the build-tool-depends field.

[eamsden]

(I filed this here because it seems likely to require updates both to cabal-to-nix as well as to the module structure of haskell.nix)

[eamsden]

It seems I misunderstood how this gets propagated through haskell.nix. Closing.