gp: gcd(0) error message unhelpful

[Michael Somos <somos@grail.cba.csuohio.edu>]

pari-dev,
    Bill wrote :

> Giving one argument is valid iff it is a vector.

Okay, you are right, however, the documentation is silent on
what happens in the case gcd(1) or gcd(x). Perhaps it should
just return what it is given as a harmless response. It would
be consistent with some other functions that way.

> Using "associative (gcd,lcm,chinese)" is wrong because we can add new functions
> at any time, and we will certainly forget to update the list.

Perhaps I am missing something here. I thought the purpose of
PARI-GP was to help users of the program to perform computations.
Having unhelpful error messages is not a desired behavior. The
word "associative" is distinctly unhelpful without some kind of
qualifier. You are welcome to come up with something, but for
now "associative (gcd,lcm,chinese)" is an easy fix. It conveys
the general idea, and will be unlikely to change in future.
Shalom, Michael