notabug quiz

[ysth]

This is a quiz. Below are 6 examples of perl "bugs" that have been reported to perl5-porters in the last 3 weeks and determined to be not bugs. One reporter, (I believe) the only perlmonk among them, had already figured out the difficulty and was providing a documentation patch to clarify things. Of the others, four are somewhat documented.

Your mission, should you choose to accept it, is to find the documentation (if any) that supports perl's actual behaviour. Or at least figure out why perl is doing what it is doing. Or at least have some fun and maybe learn something new.

use strict;
use warnings;
use vars '$x';

sub ok ($$)
{
   my ($testnum, $check) = @_;
   if ($check) {
      print "ok $testnum\n";
   } else {
      print "not ok $testnum\n"
   }
}


$x=0; { no strict 'refs'; my $x=42; my $y = 'x'; ok 1, ${$y} == 42; }

ok 2, eval 'no warnings; sub Foo::INIT { 42 } &Foo::INIT();';

$x="ad"; for ($x) { /a/gc; /\Gb?/gc; ok 3, /\Gc?/gc; }

ok 4, eval ' "(R)" =~ m(\(?r\)?)i ';

$x=1; { my $x=2; sub x {eval '$x'} } { my $x=3; ok 5, x; }

ok 6, 17.98 == 17.99 - .01;

Update: reordered the tests (before any replies) Update: verbosify ok() sub