first experimental MSYS (no cygwin) support

configure.ac

@@ -12,16 +12,21 @@ AC_PREREQ(2.53)
 # Find out what type of system we're running on
 AC_CANONICAL_BUILD
 
-# This isn't right for cygwin.
+Platform="$build_cpu-$build_vendor-$build_os"
+
+# This isn't right for msys mingw.
 PREFIX="$prefix"
 if test "$prefix" = "NONE"
 then
+  if test "$build_os" = "cygwin"
+  then
+    PREFIX="c:/cygwin$ac_default_prefix"
+  else
     PREFIX="$ac_default_prefix"
+  fi
 fi
 AC_SUBST(PREFIX)
 
-Platform="$build_cpu-$build_vendor-$build_os"
-
 case $Platform in
 powerpc-apple-darwin*)
         MACOSX=yes
@@ -42,6 +47,14 @@ fi
 AC_SUBST(WHOLE_ARCHIVE_FLAG)
 AC_SUBST(LEADING_UNDERSCORE)
 
+if test "$build_os" = "mingw32"
+then
+  LEADING_UNDERSCORE=1
+  SYMS="$SYMS -D__MINGW32__"
+fi
+AC_SUBST(LEADING_UNDERSCORE)
+AC_SUBST(SYMS)
+
 if test "$build_os" = "cygwin"
 then
   LEADING_UNDERSCORE=1

examples/makewith/global_pragma/Plugin.hs

@@ -1,4 +1,4 @@
-{-# GLOBALOPTIONS -package posix #-}
+{-# GLOBALOPTIONS -package mtl #-}
 
 module M ( resource ) where
 

src/plugins/Plugins/Env.hs

@@ -57,7 +57,7 @@ import Data.List                ( isPrefixOf, nub )
 
 import System.IO.Unsafe         ( unsafePerformIO )
 import System.Directory         ( doesFileExist )
-#ifdef CYGWIN
+#if defined(CYGWIN) || defined(__MINGW32__)
 import System.Environment       ( getEnv )
 
 import Control.Monad            ( liftM )
@@ -310,7 +310,7 @@ lookupPkg' p = withPkgEnvs env $ \fms -> go fms p
             Nothing -> go fms q     -- look in other pkgs
 
             Just package -> do
-#ifdef CYGWIN
+#if defined(CYGWIN) || defined(__MINGW32__)
                 let    libdirs = fix_topdir $ libraryDirs package
 #else
                 let    libdirs = libraryDirs package
@@ -319,7 +319,7 @@ lookupPkg' p = withPkgEnvs env $ \fms -> go fms p
                        extras  = extraLibraries package
                        deppkgs = packageDeps package
                 libs <- mapM (findHSlib libdirs) (hslibs ++ extras)
-#ifdef CYGWIN
+#if defined(CYGWIN) || defined(__MINGW32__)
 		syslibdir <- liftM ( \x -> x ++ "/SYSTEM") (getEnv "SYSTEMROOT")
 		libs' <- mapM (findDLL $ syslibdir : libdirs) extras
 #else
@@ -330,7 +330,7 @@ lookupPkg' p = withPkgEnvs env $ \fms -> go fms p
                 -- anything about that.
                 return (deppkgs, (filterJust libs,filterJust libs') )
 
-#ifdef CYGWIN
+#if defined(CYGWIN) || defined(__MINGW32__)
         -- replace $topdir
 	fix_topdir []        = []
 	fix_topdir (x:xs)    = replace_topdir x : fix_topdir xs

src/plugins/Plugins/MkTemp.hs

@@ -42,7 +42,11 @@ import Control.Monad            ( liftM )
 import Control.Exception        ( handleJust )
 import System.Directory         ( doesDirectoryExist, doesFileExist, createDirectory )
 import System.IO
+#ifndef __MINGW32__
 import System.IO.Error          ( isAlreadyExistsError )
+#else
+import System.IO.Error          ( isAlreadyExistsError, isAlreadyInUseError, isPermissionError )
+#endif
 
 import GHC.IOBase               ( IOException(IOError), 
                                   Exception(IOException),