use strict;
use warnings;
use feature "say";
#no warnings 'redefine';
sub tst {1} 
BEGIN { $a = \&tst }
sub tst {2}
BEGIN { $b = \&tst }              
say &$a;
say &$b;

##</code><code>##

perl false_postive_redefine.pl
Subroutine tst redefined at false_postive_redefine.pl line 7.
1
2

##</code><code>##

use feature "try";
use constant CHECK_HINTHASH => 0;
sub check_hinthash {warn "feature_try = ".$^H{feature_try} if CHECK_HINTHASH}
#...

BEGIN { check_hinthash() }	# feature enabled

{
  no feature qw( try );
  BEGIN { check_hinthash() }	# feature disabled
  use Try::Tiny qw( try catch );
   
  try { ... };   
}

BEGIN { check_hinthash() }	# feature enabled

# try { ... };  <-- would fail