I made it compile:

#!/usr/bin/env perl

use strict;
use warnings;
use feature qw(say);

my $cond;

do {
    push my @array, qw/x y z/ if $cond;
    push @array, qw/a b c/;
};


say  q(Ouch!);

__END__
Ouch!
[download]

Now compare it with this (your) version:

#!/usr/bin/env perl

use strict;
use warnings;
use feature qw(say);

my $cond;

do {
    push my @array, qw/x y z/ if $cond;
    push @array, qw/a b c/;
}


say  q(Ouch!);

__END__
syntax error at ./doh.pl line 15, near "say"
Execution of ./doh.pl aborted due to compilation errors.
[download]

Mmh. And i wonder what this construct should be good for.

Best regards, Karl