Autoconf archive macro to maximise warnings (gcc only)

git-svn-id: https://swig.svn.sourceforge.net/svnroot/swig/trunk/SWIG@4799 626c5289-ae23-0410-ae9c-e8d60b6d4f22

Tools/config/ac_compile_warnings.m4

@@ -0,0 +1,28 @@
+dnl Available from the GNU Autoconf Macro Archive at:
+dnl http://www.gnu.org/software/ac-archive/htmldoc/ac_compile_warnings.html
+dnl
+AC_DEFUN([AC_COMPILE_WARNINGS],
+[AC_MSG_CHECKING(maximum warning verbosity option)
+if test -n "$CXX"
+then
+  if test "$GXX" = "yes"
+  then
+    ac_compile_warnings_opt='-Wall'
+  fi
+  CXXFLAGS="$CXXFLAGS $ac_compile_warnings_opt"
+  ac_compile_warnings_msg="$ac_compile_warnings_opt for C++"
+fi
+
+if test -n "$CC"
+then
+  if test "$GCC" = "yes"
+  then
+    ac_compile_warnings_opt='-Wall'
+  fi
+  CFLAGS="$CFLAGS $ac_compile_warnings_opt"
+  ac_compile_warnings_msg="$ac_compile_warnings_msg $ac_compile_warnings_opt for C"
+fi
+AC_MSG_RESULT($ac_compile_warnings_msg)
+unset ac_compile_warnings_msg
+unset ac_compile_warnings_opt
+])