Remove all target-specific portions of Config.hs

1. If GHC is to be multi-target, these cannot be baked in at compile
   time.

2. Compile-time flags have a higher maintenance than run-time flags.

3. The old way makes build system implementation (various bootstrapping
   details) with the thing being built. E.g. GHC doesn't need to care
   about which integer library *will* be used---this is purely a crutch
   so the build system doesn't need to pass flags later when using that
   library.

4. Experience with cross compilation in Nixpkgs has shown things work
   nicer when compiler's can *optionally* delegate the bootstrapping the
   package manager. The package manager knows the entire end-goal build
   plan, and thus can make top-down decisions on bootstrapping. GHC can
   just worry about GHC, not even core library like base and ghc-prim!

1 files changed, 42 insertions, 5 deletions

diff --git a/compiler/main/SysTools.hs b/compiler/main/SysTools.hs
index 50cc6d58e5..b3dc60654e 100644
--- a/compiler/main/SysTools.hs
+++ b/compiler/main/SysTools.hs
@@ -259,6 +259,29 @@ initSysTools top_dir
                           platformIsCrossCompiling = crossCompiling
                       }
 
+       integerLibrary <- getSetting "integer library"
+       integerLibraryType <- case integerLibrary of
+         "integer-gmp" -> pure IntegerGMP
+         "integer-simple" -> pure IntegerSimple
+         _ -> pgmError $ unwords
+           [ "Entry for"
+           , show "integer library"
+           , "must be one of"
+           , show "integer-gmp"
+           , "or"
+           , show "integer-simple"
+           ]
+
+       ghcWithInterpreter <- getBooleanSetting "Use interpreter"
+       ghcWithNativeCodeGen <- getBooleanSetting "Use native code generator"
+       ghcWithSMP <- getBooleanSetting "Support SMP"
+       ghcRTSWays <- getSetting "RTS ways"
+       leadingUnderscore <- getBooleanSetting "Leading underscore"
+       useLibFFI <- getBooleanSetting "Use LibFFI"
+       ghcThreaded <- getBooleanSetting "Use Threads"
+       ghcDebugged <- getBooleanSetting "Use Debugging"
+       ghcRtsWithLibdw <- getBooleanSetting "RTS expects libdw"
+
        return $ Settings {
                     sTargetPlatform = platform,
                     sTmpDir         = normalise tmpdir,
@@ -306,8 +329,20 @@ initSysTools top_dir
                     sOpt_lc      = [],
                     sOpt_i       = [],
                     sPlatformConstants = platformConstants,
+
                     sTargetPlatformString = targetPlatformString,
-                    sTablesNextToCode = tablesNextToCode
+                    sIntegerLibrary = integerLibrary,
+                    sIntegerLibraryType = integerLibraryType,
+                    sGhcWithInterpreter = ghcWithInterpreter,
+                    sGhcWithNativeCodeGen = ghcWithNativeCodeGen,
+                    sGhcWithSMP = ghcWithSMP,
+                    sGhcRTSWays = ghcRTSWays,
+                    sTablesNextToCode = tablesNextToCode,
+                    sLeadingUnderscore = leadingUnderscore,
+                    sLibFFI = useLibFFI,
+                    sGhcThreaded = ghcThreaded,
+                    sGhcDebugged = ghcDebugged,
+                    sGhcRtsWithLibdw = ghcRtsWithLibdw
              }
 
 
@@ -383,10 +418,12 @@ linkDynLib dflags0 o_files dep_packages
         -- against libHSrts, then both end up getting loaded,
         -- and things go wrong. We therefore link the libraries
         -- with the same RTS flags that we link GHC with.
-        dflags1 = if cGhcThreaded then addWay' WayThreaded dflags0
-                                  else                     dflags0
-        dflags2 = if cGhcDebugged then addWay' WayDebug dflags1
-                                  else                  dflags1
+        dflags1 = if sGhcThreaded $ settings dflags0
+          then addWay' WayThreaded dflags0
+          else                     dflags0
+        dflags2 = if sGhcDebugged $ settings dflags1
+          then addWay' WayDebug dflags1
+          else                  dflags1
         dflags = updateWays dflags2
 
         verbFlags = getVerbFlags dflags