nconc will be infiniteLoop when (nconc x x) , x is an non-nil list

[enzo]

(setf x '(1))

(nconc x x) return 1 1 1 1 1 1 1 1 .......

(setf x nil)
(nconc x x) return nil

$ sbcl --version
SBCL 1.2.0

$ uname -a
Darwin Enzo's MBP 13.3.0 Darwin Kernel Version 13.3.0: Tue Jun 3 21:27:35 PDT 2014; root:xnu-2422.110.17~1/RELEASE_X86_64 x86_64

$ uname -a
Linux vagrant-ubuntu-saucy-64 3.13.0-34-generic #60-Ubuntu SMP Wed Aug 13 15:45:27 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux

tested in sbcl 1.1.14,1.2.0,1.2.2 ,both in my mac os x, and ubuntu

[Orivej Desh (orivej)]

This is not a bug.

You made a circular list. To print it in limited time, set *print-circle* to T, or *print-length* to a number.

And modifying a literal object, such as a quoted list, is undefined. You should have used (setf x (list 1))

[enzo (liu-enze)]

OK,my fault, thanks for letting me know.