bug #28677: Cygwin's GCC no longer supports -mno-cygwin option

* configure.ac: For Win32 environments, add a check whether the
compiler understands the -mno-cygwin option.  If not, don't use
it but suggest using a different compiler.




git-svn-id: svn://svn.savannah.nongnu.org/avrdude/trunk/avrdude@930 81a1dc3b-b13d-400b-aceb-764788c761c2

configure.ac

@@ -241,16 +241,6 @@ else
 fi
 export confsubst
 
-# See if we need to drop into the windows subdir.
-case $target in
-        *-*-mingw32* | *-*-cygwin* | *-*-windows*)
-		WINDOWS_DIRS="windows"
-		CFLAGS="${CFLAGS} -mno-cygwin -DWIN32NATIVE"
-		LDFLAGS="${LDFLAGS} -static"
-		;;
-esac
-AC_SUBST(WINDOWS_DIRS,$WINDOWS_DIRS)
-
 # If we are compiling with gcc, enable all warning and make warnings errors.
 if test "$GCC" = yes; then
     ENABLE_WARNINGS="-Wall"
@@ -276,6 +266,42 @@ if test "$GCC" = yes; then
 fi
 AC_SUBST(ENABLE_WARNINGS,$ENABLE_WARNINGS)
 
+# See if we need to drop into the windows subdir.
+case $target in
+        *-*-mingw32* | *-*-cygwin* | *-*-windows*)
+		if test "$GCC" = yes -a \( "$CC" = "cc" -o "$CC" = "gcc" \); then
+			# does this compiler support -mno-cygwin?
+			AC_MSG_CHECKING([if $CC accepts -mno-cygwin])
+
+			safe_CFLAGS=$CFLAGS
+			CFLAGS="$ENABLE_WARNINGS -mno-cygwin"
+
+			AC_TRY_COMPILE(, [ int main () { return 0 ; } ], [
+				no_cygwin=yes
+				AC_MSG_RESULT([yes])
+				], [
+				no_cygwin=no
+				AC_MSG_RESULT([no])
+				])
+			CFLAGS=$safe_CFLAGS
+
+			if test x$no_cygwin = xyes; then
+				CFLAGS="${CFLAGS} -mno-cygwin"
+			else
+				AC_MSG_NOTICE([Your compiler does not understand the -mno-cygwin option.])
+				AC_MSG_NOTICE([You might want to select an alternative compiler, like])
+				AC_MSG_NOTICE([])
+				AC_MSG_NOTICE([CC=mingw32-gcc ./configure])
+				AC_MSG_NOTICE([])
+			fi
+		fi
+		WINDOWS_DIRS="windows"
+		CFLAGS="${CFLAGS} -DWIN32NATIVE"
+		LDFLAGS="${LDFLAGS} -static"
+		;;
+esac
+AC_SUBST(WINDOWS_DIRS,$WINDOWS_DIRS)
+
 AC_CONFIG_FILES([
        doc/Makefile
        windows/Makefile