Does the existence of I/O operations always indicate there are some side
effects?

Moreover, can there be any kinds of side-effectful I/O operations besides
"calling a library I/O function" in the sense of [intro.execution]p7
(whatever "a library I/O" means)?

Are they consistent with the clause "[input.output]"?

(I strongly feel there have been something gone wrong for a long time. I
have drafted a CWG issue and sent it to wmm_at_[hidden] month ago, but there
was no reply. This time I try to follow the full directives in
https://isocpp.org/std/submit-issue, except for the link *std-discussion*
<https://lists.isocpp.org/mailman/listinfo.cgi/std-proposals> in that page
which seems to be wrong.)