"?" can start both a term (?PATTERN?) and an operator (the conditional operator). Perl has no way of knowing which one you intended here. Since it followed a sub call, Perl assumed you were specifying arguments, so it treated the "?" as the start of a term. Same goes for "/", unary-"-" and unary-"+".

Solutions: 

func() ? '-N ' : ''

[download]
(func) ? '-N ' : ''

[download]
sub func() {}
func ? '-N ' : ''

[download]

Is it just to comply with those internal functions such as grep or split, which accept a regexp as first argument, or is there a deeper reason for this seemingly oddity?

No. func ?PATTERN?; is no different than func $x+1; (and even more similar to func -3;). There's nothing special (or odd) about it.

In reply to Re: Why do I need parentheses here? by ikegami
in thread Why do I need parentheses here? by rovf

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