$ cat testpolicy.pl
#!/usr/bin/env perl
use warnings;
use strict;

my $foo => 'bar';
our $foo => 1;
our $foo => { a=>'blah', b=>'blah' };
our $foo = { a=>'blah', b=>'blah' };
my %foo = ( a=>1, b=>2 );

$ PERL5LIB=/tmp/testlib perlcritic -4 testpolicy.pl
Fat comma used in declaration at line 5, column 9.  You probably meant "=" instead of "=>".  (Severity: 4)
Fat comma used in declaration at line 6, column 10.  You probably meant "=" instead of "=>".  (Severity: 4)
Fat comma used in declaration at line 7, column 10.  You probably meant "=" instead of "=>".  (Severity: 4)