Portability problems fixed by Gnulib:
@itemize
@item
+The function @code{getopt_long_only} 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
The function @code{getopt_long_only} does not support the @samp{+}
flag in the options string on some platforms:
MacOS X 10.5, AIX 5.2, OSF/1 5.1, Solaris 10.
Portability problems not fixed by Gnulib:
@itemize
@item
-The glibc extension of using @samp{W;} in the optstring argument to
-allow @code{-W foo} to behave synonymously with @code{--foo} is not
-very reliable.
-@item
Some implementations return success instead of reporting an ambiguity
-if user's option is a prefix of two long options with the same flag:
+if user's option is a prefix of two long options with the same outcome:
FreeBSD.
@item
-Mixing a leading @samp{-} or @samp{+} with a leading @samp{:} in the
-optstring argument has inconsistent effects across platforms.
+The GNU Coding Standards discourage the use of @code{getopt_long_only}
+in new programs.
@end itemize