-This function is missing on some platforms:
-MacOS X 10.3, FreeBSD 5.2.1, OpenBSD 3.8, AIX 4.3.2, HP-UX 11, IRIX 6.5, OSF/1 5.1, Solaris 10, mingw, Interix 3.5, BeOS.
+This function returns incorrect values in some cases, such as when
+given an empty needle:
+glibc <= 2.0, Cygwin 1.5.x.
+@item
+This function has quadratic instead of linear worst-case complexity on some
+platforms:
+glibc 2.8, FreeBSD 6.2, NetBSD 3.0, AIX 5.1, Cygwin 1.5.x.
+@end itemize
+
+Portability problems not fixed by Gnulib:
+@itemize