my %hash = (
    foo => 1,
    bar => quux($blorf),
);
my $result = frobnitz(\%hash); # ok
my $result = frobnitz( %hash); # also ok

# ---

my $hashref = (
    foo => 1,
    bar => quux($blorf),
);
my $result = frobnitz( $hashref); # ok

# ---

frobnitz( { foo => 1, bar => scalar bar($quux) } ); # not ok