Make ambient MinGW support a proper settings

Get rid of `USE_INPLACE_MINGW_TOOLCHAIN` and use a settings file entry
instead.

The CPP setting was originally introduced in f065b6b012.

14 files changed, 55 insertions, 40 deletions

diff --git a/compiler/GHC/Driver/Session.hs b/compiler/GHC/Driver/Session.hs
index 2a4d5aae3c..ccf4d18f2f 100644
--- a/compiler/GHC/Driver/Session.hs
+++ b/compiler/GHC/Driver/Session.hs
@@ -4544,8 +4544,9 @@ compilerInfo dflags
     showBool False = "NO"
     platform  = targetPlatform dflags
     isWindows = platformOS platform == OSMinGW32
+    useInplaceMinGW = toolSettings_useInplaceMinGW $ toolSettings dflags
     expandDirectories :: FilePath -> Maybe FilePath -> String -> String
-    expandDirectories topd mtoold = expandToolDir mtoold . expandTopDir topd
+    expandDirectories topd mtoold = expandToolDir useInplaceMinGW mtoold . expandTopDir topd
 
 
 wordAlignment :: Platform -> Alignment
diff --git a/compiler/GHC/Settings.hs b/compiler/GHC/Settings.hs
index 73f3b97b54..679d0266fe 100644
--- a/compiler/GHC/Settings.hs
+++ b/compiler/GHC/Settings.hs
@@ -22,6 +22,7 @@ module GHC.Settings
   , sLdSupportsFilelist
   , sLdIsGnuLd
   , sGccSupportsNoPie
+  , sUseInplaceMinGW
   , sPgm_L
   , sPgm_P
   , sPgm_F
@@ -89,6 +90,7 @@ data ToolSettings = ToolSettings
   , toolSettings_ldSupportsFilelist      :: Bool
   , toolSettings_ldIsGnuLd               :: Bool
   , toolSettings_ccSupportsNoPie         :: Bool
+  , toolSettings_useInplaceMinGW         :: Bool
 
   -- commands for particular phases
   , toolSettings_pgm_L       :: String
@@ -190,6 +192,8 @@ sLdIsGnuLd :: Settings -> Bool
 sLdIsGnuLd = toolSettings_ldIsGnuLd . sToolSettings
 sGccSupportsNoPie :: Settings -> Bool
 sGccSupportsNoPie = toolSettings_ccSupportsNoPie . sToolSettings
+sUseInplaceMinGW :: Settings -> Bool
+sUseInplaceMinGW = toolSettings_useInplaceMinGW . sToolSettings
 
 sPgm_L :: Settings -> String
 sPgm_L = toolSettings_pgm_L . sToolSettings
diff --git a/compiler/GHC/Settings/IO.hs b/compiler/GHC/Settings/IO.hs
index 1e56d1c087..7d9be2f403 100644
--- a/compiler/GHC/Settings/IO.hs
+++ b/compiler/GHC/Settings/IO.hs
@@ -35,12 +35,6 @@ initSettings
   => String -- ^ TopDir path
   -> ExceptT SettingsError m Settings
 initSettings top_dir = do
-  -- see Note [topdir: How GHC finds its files]
-  -- NB: top_dir is assumed to be in standard Unix
-  -- format, '/' separated
-  mtool_dir <- liftIO $ findToolDir top_dir
-        -- see Note [tooldir: How GHC finds mingw on Windows]
-
   let installed :: FilePath -> FilePath
       installed file = top_dir </> file
       libexec :: FilePath -> FilePath
@@ -58,24 +52,31 @@ initSettings top_dir = do
     Nothing -> throwE $ SettingsError_BadData $
       "Can't parse " ++ show settingsFile
   let mySettings = Map.fromList settingsList
+      getBooleanSetting :: String -> ExceptT SettingsError m Bool
+      getBooleanSetting key = either pgmError pure $
+        getRawBooleanSetting settingsFile mySettings key
+
+  -- On Windows, by mingw is often distributed with GHC,
+  -- so we look in TopDir/../mingw/bin,
+  -- as well as TopDir/../../mingw/bin for hadrian.
+  -- But we might be disabled, in which we we don't do that.
+  useInplaceMinGW <- getBooleanSetting "Use inplace MinGW toolchain"
+
+  -- see Note [topdir: How GHC finds its files]
+  -- NB: top_dir is assumed to be in standard Unix
+  -- format, '/' separated
+  mtool_dir <- liftIO $ findToolDir useInplaceMinGW top_dir
+        -- see Note [tooldir: How GHC finds mingw on Windows]
+
   -- See Note [Settings file] for a little more about this file. We're
   -- just partially applying those functions and throwing 'Left's; they're
   -- written in a very portable style to keep ghc-boot light.
   let getSetting key = either pgmError pure $
         getRawFilePathSetting top_dir settingsFile mySettings key
       getToolSetting :: String -> ExceptT SettingsError m String
-      getToolSetting key = expandToolDir mtool_dir <$> getSetting key
-      getBooleanSetting :: String -> ExceptT SettingsError m Bool
-      getBooleanSetting key = either pgmError pure $
-        getRawBooleanSetting settingsFile mySettings key
+      getToolSetting key = expandToolDir useInplaceMinGW mtool_dir <$> getSetting key
   targetPlatformString <- getSetting "target platform string"
   myExtraGccViaCFlags <- getSetting "GCC extra via C opts"
-  -- On Windows, mingw is distributed with GHC,
-  -- so we look in TopDir/../mingw/bin,
-  -- as well as TopDir/../../mingw/bin for hadrian.
-  -- It would perhaps be nice to be able to override this
-  -- with the settings file, but it would be a little fiddly
-  -- to make that possible, so for now you can't.
   cc_prog <- getToolSetting "C compiler command"
   cc_args_str <- getSetting "C compiler flags"
   cxx_args_str <- getSetting "C++ compiler flags"
@@ -162,6 +163,7 @@ initSettings top_dir = do
       , toolSettings_ldSupportsFilelist      = ldSupportsFilelist
       , toolSettings_ldIsGnuLd               = ldIsGnuLd
       , toolSettings_ccSupportsNoPie         = gccSupportsNoPie
+      , toolSettings_useInplaceMinGW         = useInplaceMinGW
 
       , toolSettings_pgm_L   = unlit_path
       , toolSettings_pgm_P   = (cpp_prog, cpp_args)
diff --git a/compiler/GHC/SysTools/BaseDir.hs b/compiler/GHC/SysTools/BaseDir.hs
index 03169523c6..c0a1fa2cee 100644
--- a/compiler/GHC/SysTools/BaseDir.hs
+++ b/compiler/GHC/SysTools/BaseDir.hs
@@ -139,12 +139,16 @@ play nice with the system compiler instead.
 
 -- | Expand occurrences of the @$tooldir@ interpolation in a string
 -- on Windows, leave the string untouched otherwise.
-expandToolDir :: Maybe FilePath -> String -> String
-#if defined(mingw32_HOST_OS) && !defined(USE_INPLACE_MINGW_TOOLCHAIN)
-expandToolDir (Just tool_dir) s = expandPathVar "tooldir" tool_dir s
-expandToolDir Nothing         _ = panic "Could not determine $tooldir"
+expandToolDir
+  :: Bool -- ^ whether we are use the ambiant mingw toolchain
+  -> Maybe FilePath -- ^ tooldir
+  -> String -> String
+#if defined(mingw32_HOST_OS)
+expandToolDir False (Just tool_dir) s = expandPathVar "tooldir" tool_dir s
+expandToolDir False Nothing         _ = panic "Could not determine $tooldir"
+expandToolDir True  _               s = s
 #else
-expandToolDir _ s = s
+expandToolDir _ _ s = s
 #endif
 
 -- | Returns a Unix-format path pointing to TopDir.
@@ -180,10 +184,11 @@ tryFindTopDir Nothing
 -- tooldir can't be located, or returns @Just tooldirpath@.
 -- If the distro toolchain is being used we treat Windows the same as Linux
 findToolDir
-  :: FilePath -- ^ topdir
+  :: Bool -- ^ whether we are use the ambiant mingw toolchain
+  -> FilePath -- ^ topdir
   -> IO (Maybe FilePath)
-#if defined(mingw32_HOST_OS) && !defined(USE_INPLACE_MINGW_TOOLCHAIN)
-findToolDir top_dir = go 0 (top_dir </> "..") []
+#if defined(mingw32_HOST_OS)
+findToolDir False top_dir = go 0 (top_dir </> "..") []
   where maxDepth = 3
         go :: Int -> FilePath -> [FilePath] -> IO (Maybe FilePath)
         go k path tried
@@ -196,6 +201,7 @@ findToolDir top_dir = go 0 (top_dir </> "..") []
               if oneLevel
                 then return (Just path)
                 else go (k+1) (path </> "..") tried
+findToolDir True _ = return Nothing
 #else
-findToolDir _ = return Nothing
+findToolDir _ _ = return Nothing
 #endif
diff --git a/configure.ac b/configure.ac
index fd7f3ed079..38289862b9 100644
--- a/configure.ac
+++ b/configure.ac
@@ -558,7 +558,6 @@ fi
 AC_SUBST(CrossCompiling)
 AC_SUBST(CrossCompilePrefix)
 AC_SUBST(TargetPlatformFull)
-AC_SUBST(EnableDistroToolchain)
 
 dnl ** Which gcc to use?
 dnl --------------------------------------------------------------
diff --git a/distrib/configure.ac.in b/distrib/configure.ac.in
index 533be9dfac..6f9237cb32 100644
--- a/distrib/configure.ac.in
+++ b/distrib/configure.ac.in
@@ -82,6 +82,13 @@ FIND_PYTHON
 
 XCODE_VERSION()
 
+AC_ARG_ENABLE(distro-toolchain,
+[AS_HELP_STRING([--enable-distro-toolchain],
+                [Do not use bundled Windows toolchain binaries.])],
+  [FP_CAPITALIZE_YES_NO(["$enableval"], [EnableDistroToolchain])],
+  [EnableDistroToolchain=@SettingsUseDistroMINGW@]
+)
+
 dnl ** Which gcc to use?
 dnl --------------------------------------------------------------
 AC_PROG_CC([gcc clang])
diff --git a/hadrian/bindist/Makefile b/hadrian/bindist/Makefile
index 84fb7f8bdd..4276fe7a86 100644
--- a/hadrian/bindist/Makefile
+++ b/hadrian/bindist/Makefile
@@ -141,6 +141,7 @@ lib/settings :
 	@echo ',("LLVM llc command", "$(SettingsLlcCommand)")' >> $@
 	@echo ',("LLVM opt command", "$(SettingsOptCommand)")' >> $@
 	@echo ',("LLVM clang command", "$(SettingsClangCommand)")' >> $@
+	@echo ',("Use inplace MinGW toolchain", "$(SettingsUseDistroMINGW)")' >> $@
 	@echo
 	@echo ',("Use interpreter", "$(GhcWithInterpreter)")' >> $@
 	@echo ',("Support SMP", "$(GhcWithSMP)")' >> $@
@@ -148,7 +149,7 @@ lib/settings :
 	@echo ',("Tables next to code", "$(TablesNextToCode)")' >> $@
 	@echo ',("Leading underscore", "$(LeadingUnderscore)")' >> $@
 	@echo ',("Use LibFFI", "$(UseLibffiForAdjustors)")' >> $@
-	@echo ",(\"RTS expects libdw\", \"$(GhcRtsWithLibdw)\")" >> $@
+	@echo ',("RTS expects libdw", "$(GhcRtsWithLibdw)")' >> $@
 	@echo "]" >> $@
 
 # We need to install binaries relative to libraries.
diff --git a/hadrian/cfg/system.config.in b/hadrian/cfg/system.config.in
index e8a300d401..860c12fbec 100644
--- a/hadrian/cfg/system.config.in
+++ b/hadrian/cfg/system.config.in
@@ -96,8 +96,6 @@ project-patch-level1  = @ProjectPatchLevel1@
 project-patch-level2  = @ProjectPatchLevel2@
 project-git-commit-id = @ProjectGitCommitId@
 
-system-use-distro-mingw  = @SettingsUseDistroMINGW@
-
 # Compilation and linking flags:
 #===============================
 
@@ -164,6 +162,7 @@ settings-touch-command = @SettingsTouchCommand@
 settings-clang-command = @SettingsClangCommand@
 settings-llc-command = @SettingsLlcCommand@
 settings-opt-command = @SettingsOptCommand@
+settings-use-distro-mingw = @SettingsUseDistroMINGW@
 
 target-word-size = @TargetWordSize@
 target-word-big-endian = @TargetWordBigEndian@
diff --git a/hadrian/src/Oracles/Flag.hs b/hadrian/src/Oracles/Flag.hs
index 535a0a0138..ca66f38582 100644
--- a/hadrian/src/Oracles/Flag.hs
+++ b/hadrian/src/Oracles/Flag.hs
@@ -25,7 +25,6 @@ data Flag = ArSupportsAtFile
           | HaveLibMingwEx
           | UseSystemFfi
           | BootstrapThreadedRts
-          | SystemDistroMINGW
           | UseLibffiForAdjustors
 
 -- Note, if a flag is set to empty string we treat it as set to NO. This seems
@@ -47,7 +46,6 @@ flag f = do
             HaveLibMingwEx       -> "have-lib-mingw-ex"
             UseSystemFfi         -> "use-system-ffi"
             BootstrapThreadedRts -> "bootstrap-threaded-rts"
-            SystemDistroMINGW    -> "system-use-distro-mingw"
             UseLibffiForAdjustors -> "use-libffi-for-adjustors"
     value <- lookupValueOrError configFile key
     when (value `notElem` ["YES", "NO", ""]) . error $ "Configuration flag "
diff --git a/hadrian/src/Oracles/Setting.hs b/hadrian/src/Oracles/Setting.hs
index e58851057a..104cbc0046 100644
--- a/hadrian/src/Oracles/Setting.hs
+++ b/hadrian/src/Oracles/Setting.hs
@@ -125,6 +125,7 @@ data SettingsFileSetting
     | SettingsFileSetting_ClangCommand
     | SettingsFileSetting_LlcCommand
     | SettingsFileSetting_OptCommand
+    | SettingsFileSetting_DistroMinGW
 
 -- | Look up the value of a 'Setting' in @cfg/system.config@, tracking the
 -- result.
@@ -215,6 +216,7 @@ settingsFileSetting key = lookupValueOrError configFile $ case key of
     SettingsFileSetting_ClangCommand -> "settings-clang-command"
     SettingsFileSetting_LlcCommand -> "settings-llc-command"
     SettingsFileSetting_OptCommand -> "settings-opt-command"
+    SettingsFileSetting_DistroMinGW -> "settings-use-distro-mingw"
 
 -- | An expression that looks up the value of a 'Setting' in @cfg/system.config@,
 -- tracking the result.
diff --git a/hadrian/src/Rules/Generate.hs b/hadrian/src/Rules/Generate.hs
index d760dd55db..19ff80f6ea 100644
--- a/hadrian/src/Rules/Generate.hs
+++ b/hadrian/src/Rules/Generate.hs
@@ -242,7 +242,6 @@ generateGhcPlatformH = do
     hostOs         <- chooseSetting HostOs        TargetOs
     hostVendor     <- chooseSetting HostVendor    TargetVendor
     ghcUnreg       <- getFlag    GhcUnregisterised
-    inplaceTools   <- getFlag    SystemDistroMINGW
     return . unlines $
         [ "#if !defined(__GHCPLATFORM_H__)"
         , "#define __GHCPLATFORM_H__"
@@ -270,8 +269,6 @@ generateGhcPlatformH = do
         , ""
         ]
         ++
-        [ "#define USE_INPLACE_MINGW_TOOLCHAIN 1" | inplaceTools ]
-        ++
         [ "#define UnregisterisedCompiler 1" | ghcUnreg ]
         ++
         [ ""
@@ -326,6 +323,7 @@ generateSettings = do
         , ("LLVM llc command", expr $ settingsFileSetting SettingsFileSetting_LlcCommand)
         , ("LLVM opt command", expr $ settingsFileSetting SettingsFileSetting_OptCommand)
         , ("LLVM clang command", expr $ settingsFileSetting SettingsFileSetting_ClangCommand)
+        , ("Use inplace MinGW toolchain", expr $ settingsFileSetting SettingsFileSetting_DistroMinGW)
 
         , ("Use interpreter", expr $ yesNo <$> ghcWithInterpreter)
         , ("Support SMP", expr $ yesNo <$> targetSupportsSMP)
diff --git a/mk/config.mk.in b/mk/config.mk.in
index 18199bddd2..6cdd6c07af 100644
--- a/mk/config.mk.in
+++ b/mk/config.mk.in
@@ -487,6 +487,7 @@ SettingsTouchCommand = @SettingsTouchCommand@
 SettingsClangCommand = @SettingsClangCommand@
 SettingsLlcCommand = @SettingsLlcCommand@
 SettingsOptCommand = @SettingsOptCommand@
+SettingsUseDistroMINGW = @SettingsUseDistroMINGW@
 
 #-----------------------------------------------------------------------------
 # C compiler
diff --git a/mk/project.mk.in b/mk/project.mk.in
index 4f82b1607a..bf79614c24 100644
--- a/mk/project.mk.in
+++ b/mk/project.mk.in
@@ -127,7 +127,6 @@ BuildVendor_CPP         = @BuildVendor_CPP@
 # Valid options: YES/NO
 #
 LeadingUnderscore=@LeadingUnderscore@
-SettingsUseDistroMINGW=@SettingsUseDistroMINGW@
 
 # Pin a suffix on executables? If so, what (Windows only).
 exeext0=@exeext_host@
diff --git a/rts/include/ghc.mk b/rts/include/ghc.mk
index 91b1c22b52..cfedf62ea8 100644
--- a/rts/include/ghc.mk
+++ b/rts/include/ghc.mk
@@ -165,9 +165,6 @@ $$(includes_$1_H_PLATFORM) : rts/include/ghc.mk rts/include/Makefile | $$$$(dir
 	@echo "#define BUILD_VENDOR  \"$(BuildVendor_$1_CPP)\""     >> $$@
 	@echo "#define HOST_VENDOR  \"$(HostVendor_$1_CPP)\""       >> $$@
 	@echo                                                       >> $$@
-ifeq "$$(SettingsUseDistroMINGW)" "YES"
-	@echo "#define USE_INPLACE_MINGW_TOOLCHAIN 1"               >> $$@
-endif
 ifeq "$$(GhcUnregisterised)" "YES"
 	@echo "#define UnregisterisedCompiler 1"                    >> $$@
 endif
@@ -236,6 +233,7 @@ $(includes_SETTINGS) : rts/include/Makefile | $$(dir $$@)/.
 	@echo ',("LLVM llc command", "$(SettingsLlcCommand)")' >> $@
 	@echo ',("LLVM opt command", "$(SettingsOptCommand)")' >> $@
 	@echo ',("LLVM clang command", "$(SettingsClangCommand)")' >> $@
+	@echo ',("Use inplace MinGW toolchain", "$(SettingsUseDistroMINGW)")' >> $@
 	@echo
 	@echo ',("Use interpreter", "$(GhcWithInterpreter)")' >> $@
 	@echo ',("Support SMP", "$(GhcWithSMP)")' >> $@
@@ -243,7 +241,7 @@ $(includes_SETTINGS) : rts/include/Makefile | $$(dir $$@)/.
 	@echo ',("Tables next to code", "$(TablesNextToCode)")' >> $@
 	@echo ',("Leading underscore", "$(LeadingUnderscore)")' >> $@
 	@echo ',("Use LibFFI", "$(UseLibffiForAdjustors)")' >> $@
-	@echo ",(\"RTS expects libdw\", \"$(GhcRtsWithLibdw)\")" >> $@
+	@echo ',("RTS expects libdw", "$(GhcRtsWithLibdw)")' >> $@
 	@echo "]" >> $@