cabal v2-compile task

[fommil]

It would be very useful to have a v2-compile task that uses the correct version of with-compiler for the project. This would be complementary to v2-repl.

For example, this could be used by downstream tools (such as flycheck) as an alternative to invoking a mystery meat ghc directly.

The .ghc.* dir mechanism will kick in naturally thereafter.

It would be even better if there was a way to invoke said compiler, for a given package, with all the flags enabled, e.g. language extensions and warnings / errors.

[hvr]

doesn't cabal v2-exec ghc -- <flags> kinda implement this magic? (i.e. ghc will be substituted by whatever with-compiler was pointing to)

However, getting all the ghc-options is tricker as you'd need a specific component specified as target; this is something that the cabal show-build-info (see #2771) was supposed to help with -- or what @DanielG's http://hackage.haskell.org/package/cabal-helper should be able to help with until we get that.

[fommil]

umm, ok, that seems to do exactly what I want. I don't know how I didn't see this before 😖