If I understand the documentation, you can remove eval from there, as it's useless for qr{}.

Well, as far as I can tell, the code the OP posted doesn't make use of the eval feature at all , the code section is a literal

literal

variable aka "dynamic" aka it throws error :)

$ perl -E " $_ = 123; $f = '(?{ warn pos })';  m/\d$f/; "
Eval-group not allowed at runtime, use re 'eval' in regex m/\d(?{ warn
+ pos })/ at -e line 1.

$ perl -E " $_ = 123; $f = '(?{ warn pos })';  $g = qr/\d$f/; m/$g/"
Eval-group not allowed at runtime, use re 'eval' in regex m/\d(?{ warn
+ pos })/ at -e line 1.
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I believe whatever the OPs real code, he got this error message so he added the "solution"

I also believe there is no need for any of this stuff :) if all the OP is doing is building a data structure, simply match in a loop and use %+ or use Regexp::Grammars

Can you please let me know how to make use of %+ so to match in a loop even if the submatch in a pattern string fails?

Can you please let me know how to make use of %+ so to match in a loop even if the submatch in a pattern string fails?

um, \d always fails :)

#!/usr/bin/perl --
use strict;
use warnings;
use Data::Dump qw/ dd /;
my $cool = qr/
  (?<key>
      \s*
      (?<key2>\w+)
      \s*
      (?<keyQ>\w+)
      \s*
      (?<NEVER>\d*)
   )
/x;
my $beans = 'castor cocoa coffee pinto navy Mayocoba';

while( $beans =~ m{$cool}g ){
    dd( \%+ );
}
__END__
{
  # tied Tie::Hash::NamedCapture
  key   => "castor cocoa ",
  key2  => "castor",
  keyQ  => "cocoa",
  NEVER => "",
}
{
  # tied Tie::Hash::NamedCapture
  key   => "coffee pinto ",
  key2  => "coffee",
  keyQ  => "pinto",
  NEVER => "",
}
{
  # tied Tie::Hash::NamedCapture
  key   => "navy Mayocoba",
  key2  => "navy",
  keyQ  => "Mayocoba",
  NEVER => "",
}
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As you pointed out, There was a typo in code snippet 2. I have changed $pattern1 with $pattern2 in code snippet 2. But I am getting different out. Is it because I am using version 5.10 ?