#!/usr/bin/perl ######################################
# Check installed CPAN modules for use of "use vars" #
# Because Perl 5.28.0 removes discouraged "use vars" #
# https://perlmonks.org/index.pl?node_id=1217408     #
######################################################

use strict;
use warnings;

use autodie;
use Config '%Config';
use ExtUtils::Installed;

for (split $Config{path_sep}, $ENV{PATH}) {
   $|++ if -x "$_/grep"
}
die "you need grep" unless $|;

my $t    = time;
my $m    = ExtUtils::Installed->new;
my @temp = $m->modules();
my @cpan = ();

for (@temp) {
    my @x = $m->files($_);
    push @cpan, @x;
}
@cpan = grep /site.*\.pm$/, @cpan;
my $opt = 0;

if (@ARGV) { $opt = 1 }
else {
print qq~Checking CPAN modules for "use vars" in Perl version $^V ~.
qq~(removed in Perl 5.28)\nhttps://metacpan.org/pod/release/XSAWYE~.
qq~RX/perl-5.28.0/pod/perldelta.pod#Removal-of-use-vars  \n(Invoke~.
qq~ with any arg to skip questions and generate a list of modules.) \n\n~;

print qq~The list may be big and printing progress makes it a bit slower. 
Default: display progress, format output and print offending lines of 
code. Press return to start or n for no progress and list output. y/N~; 

chomp($opt = <STDIN>); $opt = 1 if $opt and lc $opt eq 'n';
}
my $INC = join '|', @INC;
my $n   = 0;
my $g   = 0;

for my $c (@cpan) {
   print "\rChecking: ","$n\tFound: $g\t" unless $opt;
   if (@_ = `grep 'use vars' $c`) {
      (my $f = $c) =~ s/($INC)//;
      $f =~ s,^/,,;
      $f =~ s,/,::,g;
      $f =~ s/\.pm$//;
      s/^\s+/  / for @_;
      $_{$f}=join"\n ",@_;
      $g++
   }
   $n++
}
if ($opt) {
   print "$_\n" for sort keys %_
}
else {
   $m = scalar keys %_;
   $t = time - $t;

   print qq~$m CPAN modules  (out of $n) found with "use vars"!\n~;
   print "$_:\n $_{$_}","-"x60,"\n" for sort keys %_;

   print qq~$m CPAN modules  (out of $n) found with "use vars"!\n~;
   print "That took $t secs (grep searched ",sprintf("%0d",$m/$t),
   " modules/second).\n";
}