Acceptable, probably, but if you merely want to print a warning in addition to making the test fail, I'd say do is your best choice:

open (FH, '>', '/tmp/x/logfile') or do {
    warn "Cannot open file [$!]";
    return 1;
};
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There may well be more idiomatic ways of doing (no pun intended) this that I'm not aware of. My monastic brothers will (probably) be happy to chime in!