dnl GNOME_COMPILE_WARNINGS
dnl Turn on many useful compiler warnings
dnl For now, only works on GCC
AC_DEFUN([GNOME_COMPILE_WARNINGS],[
  AC_ARG_ENABLE(compile-warnings, 
    [  --enable-compile-warnings=[no/minimum/yes]	Turn on compiler warnings.],,enable_compile_warnings=minimum)

  AC_ARG_ENABLE(warn-unused,
    [  --enable-warn-unused    Warn about unused variables and parameters],,
    enable_warn_unused=no)

  AC_MSG_CHECKING(what "unused" warning flags to use)
  wunusedCFLAGS=
  if test "x$enable_warn_unused" = xyes ; then
    wunusedCFLAGS='-Wunused'
  else
    wunusedCFLAGS='-Wno-unused'
  fi
  AC_MSG_RESULT($wunusedCFLAGS)

  AC_MSG_CHECKING(what warning flags to pass to the C compiler)
  warnCFLAGS=
  if test "x$enable_compile_warnings" != "xno"; then
    if test "x$GCC" = "xyes"; then
      case " $CFLAGS " in
      *[\ \	]-Wall[\ \	]*) ;;
      *) warnCFLAGS="-Wall" ;;
      esac

      if test "x$enable_compile_warnings" = "xyes"; then
	warnCFLAGS="$warnCFLAGS -W $wunusedCFLAGS -Wmissing-prototypes -Wmissing-declarations -Wpointer-arith"
      fi
    fi
  fi
  AC_MSG_RESULT($warnCFLAGS)

  AC_ARG_ENABLE(iso-c,
    [  --enable-iso-c          Try to warn if code is not ISO C ],,
    enable_iso_c=no)

  AC_MSG_CHECKING(what language compliance flags to pass to the C compiler)
  complCFLAGS=
  if test "x$enable_iso_c" != "xno"; then
    if test "x$GCC" = "xyes"; then
      case " $CFLAGS " in
      *[\ \	]-ansi[\ \	]*) ;;
      *) complCFLAGS="$complCFLAGS -ansi" ;;
      esac

      case " $CFLAGS " in
      *[\ \	]-pedantic[\ \	]*) ;;
      *) complCFLAGS="$complCFLAGS -pedantic" ;;
      esac
    fi
  fi
  AC_MSG_RESULT($complCFLAGS)
  CFLAGS="$CFLAGS $warnCFLAGS $complCFLAGS"
])