That's correct: if you add a module which is (indirectly) imported by DynFlags, you have to tell ghc.mk about it so that the Windows DLL splitting hack continues to work. Edward Excerpts from Simon Peyton Jones via ghc-devs's message of 2017-03-16 17:49:43 +0000:
If you add a module to GHC, I know you need to extend ghc.cabal.in. But also ghc.mk? Otherwise I get hits
If you add a module to GHC, I know you need to extend ghc.cabal.in. But also ghc.mk? Otherwise I get hits /usr/bin/ar: creating rts/dist/build/libHSrts_debug.a
Reachable modules from DynFlags out of date
Please fix compiler/ghc.mk, or building DLLs on Windows may break (#7780)
Extra modules: CoreOpt
make[1]: *** [compiler/stage2/dll-split.stamp] Error 1
make[1]: *** Waiting for unfinished jobs....
make: *** [all] Error 2
Is it necessary to have two places to extend?
Simon