Add --ghc-options arg

Stackage/CompleteBuild.hs

@@ -1,6 +1,7 @@
 {-# LANGUAGE NoImplicitPrelude #-}
 {-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE RecordWildCards   #-}
+{-# OPTIONS_GHC -fno-warn-type-defaults #-}
 module Stackage.CompleteBuild
     ( BuildType (..)
     , BumpType (..)
@@ -41,6 +42,7 @@ data BuildFlags = BuildFlags
     , bfEnableLibProfile :: !Bool
     , bfVerbose          :: !Bool
     , bfSkipCheck        :: !Bool
+    , bfGhcOptions       :: !String
     } deriving (Show)
 
 data BuildType = Nightly | LTS BumpType
@@ -210,6 +212,7 @@ getPerformBuild buildFlags Settings {..} = PerformBuild
     , pbEnableLibProfiling = bfEnableLibProfile buildFlags
     , pbVerbose = bfVerbose buildFlags
     , pbAllowNewer = bfSkipCheck buildFlags
+    , pbGhcOptions = bfGhcOptions buildFlags
     }
 
 -- | Make a complete plan, build, test and upload bundle, docs and

Stackage/InstallBuild.hs

@@ -51,6 +51,7 @@ getPerformBuild plan InstallFlags{..} =
     , pbEnableLibProfiling = ifEnableLibProfiling
     , pbVerbose            = ifVerbose
     , pbAllowNewer         = ifSkipCheck
+    , pbGhcOptions         = []
     }
 
 -- | Install stackage from an existing build plan.

Stackage/PerformBuild.hs

@@ -69,6 +69,7 @@ data PerformBuild = PerformBuild
     , pbVerbose            :: Bool
     , pbAllowNewer         :: Bool
     -- ^ Pass --allow-newer to cabal configure
+    , pbGhcOptions :: String
     }
 
 data PackageInfo = PackageInfo

Stackage/ShakeBuild.hs

@@ -323,7 +323,7 @@ packageTarget env@Env{..} name plan = do
     envmap <- liftIO (fmap (Shake.Env . (++ defaultEnv envPB pwd)) getEnvironment)
     unpack env name version
     configure env dir envmap plan
-    () <- cmd cwd envmap "cabal" "build" "--ghc-options=-O0"
+    () <- cmd cwd envmap "cabal" "build" ("--ghc-options=" <> pbGhcOptions envPB)
     register dir envmap envRegLock
     makeTargetFile (targetForPackage envShake name version)
     where dir = pkgDir env name version

app/stackage.hs

@@ -90,7 +90,13 @@ main =
              help "Output verbose detail about the build steps") <*>
         switch
             (long "skip-check" <>
-             help "Skip the check phase, and pass --allow-newer to cabal configure")
+             help "Skip the check phase, and pass --allow-newer to cabal configure") <*>
+        option
+            auto
+            (long "ghc-options" <>
+             metavar "OPTIONS" <>
+             showDefault <>
+             help "GHC options")
 
     nightlyUploadFlags = fromString <$> strArgument
         (metavar "DATE" <>