configure: check for -Wpointer-sign and turn it off

[Mike McCormack]

gcc with -Wpointer-sign enabled by default spits out alot of useless 
errors when compiling Wine.  Turn it off if we find it.

Mike


ChangeLog:
* check for -Wpointer-sign and turn it off
-------------- next part --------------
Index: configure.ac
===================================================================
RCS file: /home/wine/wine/configure.ac,v
retrieving revision 1.370
diff -u -p -r1.370 configure.ac
--- configure.ac	30 Jun 2005 20:46:59 -0000	1.370
+++ configure.ac	1 Jul 2005 09:02:10 -0000
@@ -837,6 +837,32 @@ int main(void) {
   then
     EXTRACFLAGS="$EXTRACFLAGS -Wpointer-arith"
   fi
+
+  dnl Check for -Wpointer-sign turned on by default
+  dnl Wine causes alot of these warnings
+  saved_CFLAGS="$CFLAGS"
+  CFLAGS="$CFLAGS -Werror"
+  AC_CACHE_CHECK([for -Wpointer-sign warnings], ac_cv_c_pointer_sign_warnings,
+      AC_TRY_COMPILE([ void a(char*b) { *b = 0; }
+                       void c(unsigned char*d) { a( d ); } ],[],
+                     [ac_cv_c_pointer_sign_warnings=no],[ac_cv_c_pointer_sign_warnings=yes]))
+  CFLAGS="$saved_CFLAGS"
+
+  dnl Try to use -Wno-pointer-sign to turn off the warnings
+  if test "$ac_cv_c_pointer_sign_warnings" = "yes"
+  then
+    CFLAGS="$CFLAGS -Wno-pointer-sign -Werror"
+    AC_CACHE_CHECK([for -Wno-pointer-sign flag], ac_cv_c_no_pointer_sign,
+      AC_TRY_COMPILE([ void a(char*b) { *b = 0; }
+                       void c(unsigned char*d) { a( d ); } ],[],
+                     [ac_cv_c_no_pointer_sign=yes],[ac_cv_c_no_pointer_sign=no]))
+    CFLAGS="$saved_CFLAGS"
+    if test "$ac_cv_c_no_pointer_sign" = "yes"
+    then
+      CFLAGS="$CFLAGS -Wno-pointer-sign"
+    fi
+    echo CFLAGS="$CFLAGS -Wno-pointer-sign"
+  fi
 fi
 
 dnl **** Check how to define a function in assembly code ****