use strict;
use warnings;

my @defects_to_check = qw( ATTR1 ATTR3 ATTR7 );
my $alternation = join '|(?<!!)', @defects_to_check;
# previous and next lines use negative look-behind to ensure
# only defects listed without '!' preceding them get matched
my $regex = qr/(?<!!)$alternation/;

open ( my $df, '<', 'defects_file' ) or die "can't read defects_file: $!\n";
my $total_defects = 0;
my %defect_subtotals;
while ( <$df> ) {
  next unless /^DEFECTID/;
  my @defects_found = $_ =~ m/$regex/g;
  $total_defects += scalar @defects_found;
  $defect_subtotals{ $_ }++ for @defects_found;
}
close $df;

print "Found $total_defects total defects.\nDefect breakdown follows:\n";
print $_ . ":\t\t" . $defect_subtotals{$_} . "\n" for sort keys %defect_subtotals;