Not at compile time.

>perl -c -we"my %h = 'a';"
-e syntax OK
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How could it be?

>perl -c -we"my %h = f();"
-e syntax OK
[download]

I disagree with the advice you quoted. f({...}) simply forces extra complexity in the caller just to avoid doing croak if @_ % 2; (which you don't really need anyway).