Apply `--ghc-options` in stack ghci even when no packages get loaded

[mgsloan]

Via #haskell-stack, @chreekat just ran into a case where stack ghci --ghc-options ".." did not behave as expected. Namely, since this was run with the package-less global project, --ghc-options does not get applied to anything. We have a couple options for dealing with this:

• Apply CLI --ghc-options even if there are no local package targets. This is the approach I prefer.
• Warn when --ghc-options aren't getting applied to anything. This would actually be a good enhancement independently of ghci.

If both of these actions are taken, then we should make sure that stack ghci --ghc-options doesen't warn about --ghc-options not being applied.

[chreekat]

I also feel like this could also be improved with documentation somehow, since I didn't grasp that --ghc-options and --ghci-options could ever both be useful at the same time. Maybe:

--ghc-options OPTION       Additional options passed to GHC when building the project,
                           before launching the interpreter. See --ghci-options.

I know that's a global option though, so I'm not sure if the helpdoc can be tweaked when running stack ghci --help.

[mgsloan]

Yeah, it'd be tough to do conditional option docs like that. I think I'd prefer to address the root cause and just have --ghc-options always apply to ghci. For the very rare case where that would cause issues, the user can always perform a stack build --ghc-options ... followed by a stack ghci --no-build ...

[chreekat]

Yeah, to be clear I like your proposed solutions.

[mgsloan]

Easy fix! stack ghci will now use --ghc-options.

[mgsloan]

I have actually resolved this a different, better way, which is to no longer take all of the CLI build options with stack ghci.