Unix pathnames with directory starting in :ABSOLUTE followed by a symbol don't unparse.

[Richard M Kreuter]

Unix pathnames whose directories start with :ABSOLUTE followed by one of symbols :WILD, :WILD-INFERIORS, or :UP no longer have a namestring syntax, despite being valid products of PARSE-NAMESTRING:

--
$ sh ./run-sbcl.sh --no-userinit --no-sysinit
(running SBCL from: .)
This is SBCL 1.3.2.69-aff4a0f, an implementation of ANSI Common Lisp.
More information about SBCL is available at <http://www.sbcl.org/>.

SBCL is free software, provided as is, with absolutely no warranty.
It is mostly in the public domain; some portions are provided under
BSD-style licenses. See the CREDITS and COPYING files in the
distribution for more information.
* (make-pathname :directory '(:absolute :wild-inferiors))

#<PATHNAME (with no namestring)
           :HOST #<SB-IMPL::UNIX-HOST {1000406CF3}>
           :DEVICE NIL
           :DIRECTORY (:ABSOLUTE :WILD-INFERIORS)
           :NAME NIL
           :TYPE NIL
           :VERSION NIL>
* (make-pathname :directory '(:absolute :wild))

#<PATHNAME (with no namestring)
           :HOST #<SB-IMPL::UNIX-HOST {1000406CF3}>
           :DEVICE NIL
           :DIRECTORY (:ABSOLUTE :WILD)
           :NAME NIL
           :TYPE NIL
           :VERSION NIL>
* (make-pathname :directory '(:absolute :up))

#<PATHNAME (with no namestring)
           :HOST #<SB-IMPL::UNIX-HOST {1000406CF3}>
           :DEVICE NIL
           :DIRECTORY (:ABSOLUTE :UP)
           :NAME NIL
           :TYPE NIL
           :VERSION NIL>
* (pathname "/**/")

#<PATHNAME (with no namestring)
           :HOST #<SB-IMPL::UNIX-HOST {1000406CF3}>
           :DEVICE NIL
           :DIRECTORY (:ABSOLUTE :WILD-INFERIORS)
           :NAME NIL
           :TYPE NIL
           :VERSION NIL>
* (pathname "/*/")

#<PATHNAME (with no namestring)
           :HOST #<SB-IMPL::UNIX-HOST {1000406CF3}>
           :DEVICE NIL
           :DIRECTORY (:ABSOLUTE :WILD)
           :NAME NIL
           :TYPE NIL
           :VERSION NIL>
* (pathname "/../")

#<PATHNAME (with no namestring)
           :HOST #<SB-IMPL::UNIX-HOST {1000406CF3}>
           :DEVICE NIL
           :DIRECTORY (:ABSOLUTE :UP)
           :NAME NIL
           :TYPE NIL
           :VERSION NIL>
--

The attached patch rectifies, I believe.

(Aside: 19.2.2.4.3 requires :ABSOLUTE :UP to signal a FILE-ERROR, but since that is a valid thing to have on Unix, please continue not conforming to ANSI on this detail.)

Other requested info:

--
$ uname -a
Darwin m5.localdomain 14.5.0 Darwin Kernel Version 14.5.0: Wed Jul 29 02:26:53 PDT 2015; root:xnu-2782.40.9~1/RELEASE_X86_64 x86_64

* *features*

(:64-BIT :64-BIT-REGISTERS :ALIEN-CALLBACKS :ANSI-CL :ASH-RIGHT-VOPS :BSD
 :C-STACK-IS-CONTROL-STACK :COMMON-LISP :COMPARE-AND-SWAP-VOPS
 :COMPLEX-FLOAT-VOPS :CYCLE-COUNTER :DARWIN :DARWIN9-OR-BETTER :FLOAT-EQL-VOPS
 :FP-AND-PC-STANDARD-SAVE :GENCGC :IEEE-FLOATING-POINT :INLINE-CONSTANTS
 :INODE64 :INTEGER-EQL-VOP :INTERLEAVED-RAW-SLOTS :LINKAGE-TABLE :LITTLE-ENDIAN
 :MACH-EXCEPTION-HANDLER :MACH-O :MEMORY-BARRIER-VOPS :MULTIPLY-HIGH-VOPS
 :OS-PROVIDES-BLKSIZE-T :OS-PROVIDES-DLADDR :OS-PROVIDES-DLOPEN
 :OS-PROVIDES-PUTWC :OS-PROVIDES-SUSECONDS-T :PACKAGE-LOCAL-NICKNAMES
 :PRECISE-ARG-COUNT-ERROR :RAW-INSTANCE-INIT-VOPS :SB-DOC :SB-EVAL :SB-LDB
 :SB-PACKAGE-LOCKS :SB-SIMD-PACK :SB-SOURCE-LOCATIONS :SB-TEST :SB-UNICODE
 :SBCL :STACK-ALLOCATABLE-CLOSURES :STACK-ALLOCATABLE-FIXED-OBJECTS
 :STACK-ALLOCATABLE-LISTS :STACK-ALLOCATABLE-VECTORS
 :STACK-GROWS-DOWNWARD-NOT-UPWARD :SYMBOL-INFO-VOPS :UD2-BREAKPOINTS :UNIX
 :UNWIND-TO-FRAME-AND-CALL-VOP :X86-64)
--