I have a test for this exact thing in Sub::Quote. It uses the B module to check the flags. Rather than having individual functions for each flag, or generating a data structure, my test just generates a string of what flags are set, since that was simplest and gave the nicest debugging results.

From quotify.t:

my %flags;
{
  no strict 'refs';
  for my $flag (qw(
    SVs_TEMP
    SVs_OBJECT
    SVs_GMG
    SVs_SMG
    SVs_RMG
    SVf_IOK
    SVf_NOK
    SVf_POK
    SVf_OOK
    SVf_FAKE
    SVf_READONLY
    SVf_PROTECT
    SVf_BREAK
    SVp_IOK
    SVp_NOK
    SVp_POK
  )) {
    if (defined &{'B::'.$flag}) {
      $flags{$flag} = &{'B::'.$flag};
    }
  }
}
sub flags {
  my $flags = B::svref_2object(\($_[0]))->FLAGS;
  join ' ', sort grep $flags & $flags{$_}, keys %flags;
}
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  is flags($copy), flags($value),
    "$value_name: quotify doesn't modify input";
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