"So we have an existing bug. Sometimes \400 matches \400, and sometimes it matches \01\00, depending on what I would call spooky action at a distance. I'm trying to get rid of these inconsistencies. I think something should be done here, but perhaps its not what I thought it should be. My patch follows what the code was intending to do, but perhaps we should change that intention. Please guide me." -- Karl Williamson, trudging around in the depths of Unicode.
H.Merijn Brand shared with us one of the more exciting aspects of configuring perl. The embed.pl program goes through the source and pulls out the name of every function marked as public and saves them in global.sym.
H.Merijn discovered that there's no test to check see if what is
found is truly available. Configure a perl with -Duseshrplib for
example, and many are not.
Using some unportable code, he whipped up a program to list everything that was supposed to be available but wasn't. He wanted to know if a Windows expert could code up something similar that would work on that platform.
http://xrl.us/owao2
Module::Build Nicholas Clark ran into inconsistencies with $^X (the name of
the perl binary) but got things sorted out. I'm not sure if
Ken Williams pushed the changes upstream to his repository.
http://xrl.us/owao4
git-info Michael G. Schwern lamented the lack of an equivalent command
in git for svn info, so he wrote an analogue in Perl.
Aristotle thought that he had just reinvented EasyGit. Michael
had a look, was impressed, but decided that the information
eg info produced wasn't of vital importance.
http://xrl.us/owao6
libc_r detection Tony Cook supplied a very welcome patch to solve the problem of configuring perl on FreeBSD 7 with threads, when the threads compatibility shims are not installed. Chris Williams had a feeling that this would allow bug #57458 to be closed.
So Chris set about checking the results and confirmed that the patch was good and the bug was dead.
http://xrl.us/owao8
Storable While Storable was the symptom, the cause was trying
to compile XS extensions with Sun's C compiler for a perl 5.6.1
compiled with gcc.
Nicholas Clark wrote an elaborate recipe for modifying Config.pm to make things work. Andy Dougherty thought that it all made sense, but both were in agreement that the easiest way forward for Tim Smith, who posed the question initially, would be to recompile everything with Sun's compiler.
http://xrl.us/owapa
PL_ors_sv in Devel::PPPort H.Merijn Brand needed to perform a localised undef $\,
which was trivial under 5.8.x and beyond, but just about
impossible under 5.6 due to radical differences in the
underlying implementations.
He wondered if there was a way of pushing the problem off
onto Devel::PPPort. Marcus Holland-Moritz thought it was
pretty much impossible. H.Merijn contented himself with
marking the module as unsuitable for use with 5.6 and below.
upgrade already http://xrl.us/owapc
Term::Title under Cygwin Ruben Diez asked for help in figuring out a strange error with a fresh installation of Perl on a fresh copy of Cygwin running on Vista.
Alexandr Ciornii and Reini Urban diagnosed this as a rebaseall
problem, and therein lay the solution.
http://xrl.us/ovihr http://xrl.us/owape
Nicholas Clark produced what he fervently hopes is the last snapshot for perl 5.8.9, with six issues outstanding. If anything else is broken, it will be for anyone else to fix.
Slaven Rezic posted an impressive list of modules that he had tested against recent versions of 5.8-maint, and he and Nicholas went through them. A number of failures were deemed acceptable, since they represented the nailing down of greyer parts of the implementation. Other failures were due to relying on implementation bugs that were also fixed.
Of the six main problems, David Landgren posted updates for
File::Path and Ken Williams gave p5p co-maintainer
status for Pathtools.
Modules were looked at, such as IO::Mark, constant and
Business::ISBN. SUPER method caching was examined, as
were format references.
http://xrl.us/owapg
Devel::PPPort H.Merijn Brand wanted to be able to rely on Perl_pv_pretty and
Perl_pv_escape in any version of Perl. Marcus Holland-Moritz
initially said that it would be difficult, but went ahead and
did it anyway. This now gives H.Merijn a pv_display that does
UTF-8 right.
http://xrl.us/owapi
Michael G. Schwern pinned a problem in DBIx::Class::CDBICompat
to a change in behaviour of MRO (method resolution order).
Nicholas Clark hoped that Brandon Black, author of mro.c
would be able to shed some light on the matter.
Matt S. Trout said that Brandon hasn't been available to look at Perl stuff for months and so he would try and find the time to look at it, but didn't make any promises as to when that could be.
http://xrl.us/owapk
Karl Williamson wanted to get UTF-8 output from Test::More but
was stymied by Wide character in print warnings. Michael G.
Schwern offered a couple of tips to get it to work.
http://xrl.us/owapn
Slaven Rezic wondered if the patch for FreeBSD and the legacy thread library was meant to apply to 6.x or not, since there was a discrepancy between the log message and code.
Nicholas admitted that the patch was wrong and 6.x was being treated the same way... but since things continued to work on 6.x, he wasn't sure whether to take it out or leave it.
http://xrl.us/owapp
A new task that only need Perl knowledge (and an ability to use
grep or ack).
(This probably impacts much more than the core: also the Test::Harness and TAP::* modules on CPAN.)
All of the tests in t/ can now be run in parallel, if $ENV{TEST_JOBS}
is set. However, tests within each directory in ext and lib are still
run in series, with directories run in parallel. This is an adequate
heuristic, but it might be possible to relax it further, and get more
throughput. Specifically, it would be good to audit all of lib/*.t, and
make them use File::Temp.
Changes to blead and backports to 5.10 left some consting problems that caused the compiler to grumble a bit. This patch was to clean up the warnings on 5.10, and appears to be Warnocked.
http://xrl.us/owapr
Perl_mem_log_* functions Marcus Holland-Moritz discovered a nest of duplicate code in various logging functions, and factored out what he could into a workhorse function. He hinted that this patch needed to go in, so that he could deliver a putative "SV allocation tracing" patch.
http://xrl.us/owapt
-Dm and PERL_MEM_LOG Despite receiving no feedback from the above patch, Marcus went ahead and applied his SV tracing patch. This works by adding an additional field in debugging build to SVs, in which a unique serial number can be stored.
When a leak is spotted, the serial number can be read. The
code is run a second time, this time setting a break-point
on new_SV() watching for the creation of the SV with the
same serial number. From there it usually become a trivial
matter to work out who's responsible for making the mess.
http://xrl.us/owapv
Marcus Holland-Moritz isolated a problem with incorrect function prototypes for C++ and suggested an improvement. H.Merijn Brand, as Configure pumpking was a bit concerned since the change would have a potentially large impact. But as it turned out, the fact that he had switched Configure over entirely to git simplified the house-keeping tasks considerably.
http://xrl.us/owapx
clear_yystack() Marcus Holland-Moritz spotted a bug that using PERL_POISON picked up. (That is, filling the contents of deallocated pointers with garbage to trigger segfaults from attempts to dereference said freed pointers).
The problem was that a variable was freed, set to NULL, and freed again. And in real life this works out nicely.
But for the sake of correctness, Marcus wrote a patch to make things work correctly, whether PERL_POISON is defined or not.
http://xrl.us/owapz
Marcus also noticed that change #34600 corrected an erroneously
consted SV, and reflected that such problems can lie buried
for a long time since macros like SvREFCNT_dec blindly
cast away constness, thus preventing the compiler from doing
the job we asked it to do in the first place.
So he thought about how one might go about fixing it, and came up with some more preprocessor trickery that would allow the compiler to spot when constness was being cast away.
Nicholas Clark thought that this was a great idea and committed a patch to implement it. He then began to start using it, and it allowed him to fix up some problems straight away.
http://xrl.us/owap3
Steve Hay's smoke was failing, but Steve wasn't around, so Nicholas
Clark asked for someone else with access to Windows to run
the tests and provide the details to understand what was going
wrong. Tony Cook dug down and found that it was due to an
undefined subroutine &Cwd::getdcwd.
This allowed Nicholas to understand what was going wrong and suggest a fix, and Tony reported that it was good.
http://xrl.us/owap5
Renée Bäcker wanted to know if the recent Configure-fu for FreeBSD solved this bug.
http://xrl.us/owap7
Ed Avis asked if it was possible to not set $1, $2 and the
like during a pattern match with captures. He listed three bug
reports in the RT queue about them getting clobbered.
Abigail explained that this was already possible, and showed how.
Norbert Buchmuller mentioned that he had patched NEXT.pm using
the same technique (and this was one of the cited bug reports)
but was waiting for someone to review (and apply) the patch.
http://xrl.us/owap9
More bikeshed discussions continued this week on how to name Karl Williamson's Unicode fixup pragma.
http://xrl.us/owaqb
PerlIO::via leaks memory at a high rate (#59268) Nicholas Clark looked at the problem that Marc Lehmann had uncovered, and regretted to say he wouldn't be able to fix it properly in time for 5.8.9. All is not lost though, since he thought it should be possible to push out a new version via CPAN at some later date.
http://xrl.us/owaqd
chr(0400) =~ /\400/ fails for >= 400 (#59342) Karl Williamson produced a one-line fix for this problem, and Tom Christiansen wondered if this introduced yet another meaning to octal representations, backslashed or otherwise. Karl responded that it was already a mess and he just wanted it cleaned up.
Glenn Linderman suggested that a better alternative would be to outlaw octal escapes larger than \377 on 8-bit-byte platforms (as one can always work around that by using hex encodings).
Abigail, not usually known to be fond of adding new warnings to old behaviours thought that in this particular case it might be worth spitting out a warning if an \NNN octal escape (where NNN is greater than 0377) is found in a regular expression, on the basis that it would probably point out buggy assumptions.
All the people who responded were in favour of Karl's patch being applied.
http://xrl.us/owaqf
return 0 or die (#59802) Dr. Ruud coaxed some examples of this construct from real code via a web search.
http://xrl.us/owaqh
Nick Kostirya stumbled over a coredump when he used a full colon instead
of a semicolon for use Data::Dumper;. Dave Mitchell replied that this
has been fixed in 5.10.0.
http://xrl.us/owaqj
Ryan Dilworth pointed out an inconsistency in perldata regarding arrays, offsets and entries. Daniel Frederick Crisman proposed a patch to clarify matters and Marcus Holland-Moritz applied it.
http://xrl.us/owaqm
Zefram pointed out a problem with the ?> assertion showing
up in 5.10.0. Abigail thought that this was due to a variation on
the theme of leaky implementation details, like the way A* is
implemented as A(between 0 and 32767 times). Vincent Pit identified
change #29916 as the cause.
Once Vincent identified the problem, he was able to suggest a few ways for solving it, each with various costs and benefits. He produced a patch for 5.8, to get rid of the immediate show-stopper.
5.10/blead will require a different approach and more work.
http://xrl.us/owaqo
Arthur Dunham pointed out the futility of asking ncftpget to
deal with HTTP resources.
http://xrl.us/owaqq
Altblue showed that one the core tests makes an incorrect assumption, that group names may never contain spaces. If there is one, the test fails.
http://xrl.us/owaqs
Karl Williamson ran into more pre-existing errors and inconsistencies in Unicode, this time dealing with POSIX character classes. Yves Orton dashed off a patch that he expected to work and so was surprised when in fact it didn't. At the same time he sent out a personal Call For Papers for the next YAPC::Europe conference: someone ought to put a "gdb for perl hackers" session together.
http://xrl.us/owaqu
279 new + 1062 open = 1341 (+11 -9) http://xrl.us/owaqw http://rt.perl.org/rt3/NoAuth/perl5/Overview.html
http://xrl.us/owaqy
http://xrl.us/owaq2
cmp_ok() fixage warning http://xrl.us/owaq4
http://xrl.us/owaq6
David Golden began cleaning up the task of documenting Perl via git on the Perl wiki.
http://xrl.us/owaq8
John E. Malmberg ran into a Module::Build failure on VMS that he
thought had been fixed at one point by a patch that had been dropped in
the meantime. But then the test succeeded without anything else happening.
http://xrl.us/owara
John sent in some other patches for VMS, some of which Craig A. Berry
was able to apply. One dealing with cwd issues, needs to be forwarded
to the Pathtools developers (i.e. Ken Williams).
http://xrl.us/owarc
JCSS suggested that Storable could optionally delete %hash when doing
$foo=freeze(\%hash) . Nicholas Clark pointed out that when error
handling is taken into account, this becomes much more difficult than
it would appear at first glance.
http://xrl.us/oware
another Unix platform? open source BeOS! one puzzling bug http://xrl.us/owarg
This Fortnight on perl5-porters - 28 September-12 October 2008 http://xrl.us/owari
This summary was written by David Landgren.
Weekly summaries are published on http://use.perl.org/ and posted on a mailing list, (subscription: perl5-summary-subscribe@perl.org ). The archive is at http://dev.perl.org/perl5/list-summaries/ . Corrections and comments are welcome.
If you found this summary useful, please consider contributing to the Perl Foundation or attending a YAPC to help support the development of Perl.