+The function @code{getopt_long} does not obey the combination of
+@samp{+} and @samp{:} flags in the options string on some platforms:
+glibc 2.11.
+@item
+The use of @samp{W;} in the optstring argument to does not always
+allow @code{-W foo} to behave synonymously with @code{--foo}:
+glibc 2.11.
+@item