This is not a bug. X = [a,X] creates a cyclic term during the unification (this happens when a variables is unified with a compound term which contains this variable as subterm). Gnu Prolog does not handle cyclic terms. The standard unification does not perform the occurs check for efficiency reasons. There is a a predicate doing this test: unify_with_occurs_check.
unify_with_occurs_check(X, [a,X]) will fail. Daniel Le 23 mars 2012 à 15:24, Konstantin Weitz a écrit : > gprolog segfaults on X = [a,X]. > The type of machine you are using (use uname -a under Unix). > Linux open-client 3.0.0-16-generic-pae #29-Ubuntu SMP Tue Feb 14 13:56:31 UTC > 2012 i686 i686 i386 GNU/Linux > > GNU Prolog version (use gprolog --version). > Prolog top-Level (GNU Prolog) 1.4.1 > By Daniel Diaz > Copyright (C) 1999-2012 Daniel Diaz > > The precise commands we need to type to reproduce the bug. > konne@open-client:~/gprolog-1.4.1/src/TopComp$ ./gprolog > GNU Prolog 1.4.1 > By Daniel Diaz > Copyright (C) 1999-2012 Daniel Diaz > | ?- X = [a,X]. > Segmentation fault > > > -- > Ce message a été vérifié par MailScanner pour des virus ou des polluriels et > rien de suspect n'a été trouvé. > _______________________________________________ > Bug-prolog mailing list > Bug-prolog@gnu.org > https://lists.gnu.org/mailman/listinfo/bug-prolog -- Ce message a ete verifie par MailScanner pour des virus ou des polluriels et rien de suspect n'a ete trouve.
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