Term expansion is applied twice

[hurufu]

Expansion is applied twice for every term, which is not ok, if there are any side-effects like in #2602. This leads to duplicated warnings on the console.

[triska]

I cannot reproduce this. For instance, with:

term_expansion(a, b) :- write(hello).

a.

I get, upon consulting:

hello

Could you please include a test case? Thank you a lot!

[hurufu]

It is quite hard to find minimal example, but this program produces duplicated output when consulted:

:- use_module(library(format)).

user:term_expansion(G, _) :-
    portray_clause(G),
    false.

x :-
    a.

b, c.

Here is an output:

$ scryer-prolog x.pl -g halt.
x :-
   a.
b,c.
b,c.
   error(permission_error(modify,static_procedure,(',')/2),load/1).

Duplicated b,c. is unexpected.

[triska]

Thank you! Even the following shorter program shows the issue:

x.

b, c.