LOOP counts symbols in COMMON-LISP wrong

[Dima Akater]

LOOP counts symbols in package COMMON-LISP wrong.

Below is a transcript of example session, following the bug reporting guidelines. I noticed this a couple of years back. I could not reproduce the bug for packages other than COMMON-LISP.

~ $ uname -a
Linux poseidon.akater 4.19.97-gentoo-poseidon #1 SMP Wed Jan 22 13:34:43 UTC 2020 x86_64 Intel(R) Core(TM)2 Duo CPU L9400 @ 1.86GHz GenuineIntel GNU/Linux

~ $ sbcl --version
SBCL 2.0.1

~ $ rlwrap sbcl
This is SBCL 2.0.1, 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.

* *features*
(:ASDF3.3 :ASDF3.2 :ASDF3.1 :ASDF3 :ASDF2 :ASDF :OS-UNIX
 :NON-BASE-CHARS-EXIST-P :ASDF-UNICODE :X86-64 :64-BIT :ANSI-CL :COMMON-LISP
 :ELF :GENCGC :IEEE-FLOATING-POINT :LINUX :LITTLE-ENDIAN
 :PACKAGE-LOCAL-NICKNAMES :SB-CORE-COMPRESSION :SB-LDB :SB-PACKAGE-LOCKS
 :SB-THREAD :SB-UNICODE :SBCL :UNIX)

* (let ((count 0)) (do-symbols (_ (find-package :cl) count) (declare (ignore _)) (incf count)))
978
* (let ((count 0)) (loop for s being each symbol of (find-package :cl) do (incf count)) count)
978
;; for good measure
* (push #P"/home/akater/quicklisp/dists/quicklisp/software/series-20131111-git/" asdf:*central-registry*)
  (asdf:load-system :series)
* (series:collect-length (series:scan-symbols (find-package :cl)))
978
;; and yet
* (loop for s being each symbol of (find-package :cl) count s)
977

[Douglas Katzman (dougk)]

http://www.lispworks.com/documentation/HyperSpec/Body/06_ac.htm

"The count construct counts the number of times that the supplied form returns true."

(loop for x in '(nil) count x) => 0