Getting GHC's base and GHC API with different flags

[bitemyapp]

https://www.reddit.com/r/haskell/comments/49ttyc/hint_is_alive_again/d0usl1g

In other languages like Go, you can build packages of the standard library with different flags. For example, to build your library with the race condition detector enabled, the compiler will build the standard library packages that you're importing too with that setting.

I don't know if GHC or Cabal have anything like this. If they don't, I guess the only way to do it would be for me to replace my standard GHC installation with one compiled from source with -split-objs. Although the bigger problem is that every user would need to do this to avoid bloated binaries.

Is this already possible? If so, how? If not, could this be along similar lines as the profiling builds?

[mgsloan]

Split-objs support still needs to be added #1284

ghc-options and flags do support specifying stuff for snapshot packages. However, the current support for this isn't that great. You need to blow away your snapshot to make it rebuild. This will be addressed as part of #1265 . That and related issues are pretty much the highest prioirty and largest work item for stack atm. No promises that it'll happen super soon, but it's definitely something we really want to address, and hope to do so soon.