On Fri, Aug 19, 2016 at 01:37:36PM +0200, Jakub Wilk wrote:
>
> * Niko Tyni <nt...@debian.org>, 2016-08-19, 09:42:
> > This package depends and/or build-depends on libdata-alias-perl, which
> > breaks with Perl 5.24 (currently in experimental.)
>
> This dependency was added in 516add8dc237 "to avoid copying large texts in
> memory". But my understanding is that Perl >= 5.20 has copy-on-write
> strings[0], so this optimization is no longer necessary. Jessie has a
> sufficiently new version, so the use of Data::Alias can be safely dropped.
>
> [0] http://perldoc.perl.org/perl5200delta.html#Performance-Enhancements
Thanks for looking at this! That makes sense to me fwiw, but I see in
#795641 that the patch author was using 5.20 at least when sending the
patch. So presumably there was a reason for this?
> > In some cases the 'refaliasing' feature in Perl >= 5.22 may be a
> > replacement;
>
> (Lintian needs to be backportable to stable, so we couldn't easily use this
> feature yet.)
Sure. I managed to get both alternatives working at the same time with a
string eval for the newer syntax, but it does feel a bit fragile. Something
like
#!/usr/bin/perl -w
use strict;
use if $] >= 5.022, feature => 'refaliasing';
no if $] >= 5.022, warnings => 'experimental::refaliasing';
use if $] < 5.022, 'Data::Alias';
my $b = "A" x (1024 * 1000 * 1000);
if ($] >= 5.022) {
eval '\$a = \$b';
} else {
alias $a = $b;
}
print \$a, "\n";
print \$b, "\n";
which would enable a backports-friendly dependency like
Depends: perl (>= 5.22) | libdata-alias-perl
Does that seem feasible?
--
Niko Tyni nt...@debian.org
