This function does not work when the source file name ends in a slash on
some platforms:
SunOS 4.1.
+@item
+This function will not replace an existing destination on some
+platforms:
+mingw.
@end itemize
Portability problems not fixed by Gnulib:
@itemize
+This function will not replace a destination that is currently opened
+by any process:
+mingw.
@end itemize