Bug#401132: Devel::Peek enhancement

[Dominic Hargreaves]

On Wed, Jan 27, 2010 at 10:06:39AM -0800, Robert Stone wrote:
> On Wed, Jan 27, 2010 at 12:31:44PM +0200, Niko Tyni wrote:
> > 
> > Sorry for the lack of action on this.
> 
> 	No problem at all, thanks for looking into this.
> > 
> > What's wrong with Devel::Peek:SvREFCNT(\%m) ?
> 
> 	"\%m" is a reference constructor, so SvREFCNT() ends up
> reporting the reference count of that newly constructed SV.  The
> situation can be illustrated with this small script:
> 
> #!/usr/bin/perl
> use strict;
> use warnings;
> use Devel::Peek;
> my %m = (a => 'b');
> my $mr = \%m;
> Devel::Peek::Dump($mr);
> print Devel::Peek::SvREFCNT(\%m), "\n";
> 
> 	From the Dump you can see that %m (the PVHV) has a refcount of
> 2, but "Devel::Peek::SvREFCNT(\%m)" reports 1.  The reason for this can
> be illustrated by breaking that call up a little bit.  One would
> normally expect that:
> 
> Devel::Peek::SvREFCNT(\%m)
> 
> should be equivalent to
> 
> my $tmp = \%m;
> Devel::Peek::SvREFCNT($tmp)
> 
> which unsurprisingly reports a refcount of 1 for $tmp.  Nothing changes
> when $tmp is an immediate, unlabeled value on the argument stack to
> SvREFCNT() and I think that's expected and correct behavior.
> 
> 	The proposed patch solves this difficulty by always passing the
> argument from Perl by reference and then unconditionally dereferencing
> to access the target value.

Hi Robert,

Sorry for the delay in pointing this, but I forwarded this to the
upstream bug tracker and various people are discussing a fix.

https://rt.perl.org/rt3//Ticket/Display.html?id=117793

Cheers,
Dominic.