You _can_ typecast, however, like so (array to hash key value pairs)

use Data::Dumper;
use warnings;
use strict;

open FOO, "test_data.txt" or die $!;
my @A;

while(<FOO>){
  chomp;
  push @A, split /\s*=\s*/, $_, 2
}

my %H = @A;

print Dumper(\%H);
[download]

Included a maximum of 2 elements in the split, as suggested by An.Monk.

You can, and it's a good thing to know sometimes, but in this case it'll cause strange things to happen if there's more than one = on a line. Your original suggestion was better, perhaps with the enhancement of giving the split a limit, e.g. split /\s*=\s*/, $_, 2.

push/pop and shift/unshift are for arrays only, not hashes.