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This Week on perl5-porters - 10-16 February 2008

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David Landgren
February 20, 2008 15:14
This Week on perl5-porters - 10-16 February 2008
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This Week on perl5-porters - 10-16 February 2008

   "So should we punt in this case and revert to the old warning for
   "SvGAMAGICAL"? My personal opinion is to leave it. People doing
   strange things should not be surprised by strange results." -- Rick
   Delaney, debating the Principle of Least Surprise (or something like

Topics of Interest

Stratus VOS patches

   Paul Green delivered his work to make perl 5.8, 5.10 and blead work on
   Stratus VOS. The main sticking points are a filename that begins with
   a '-' (minus), and filenames longer than 32 characters.

   Some of the remaining test suite failures were due to VOS's slightly
   funky TCP stack implementation, and Paul was slightly suspicious that
   one of the failures indicated a problem in VOS's implementation of

   Martien Verbruggen explained the finer points of POSIX's "ctime"
   behaviour to help Paul understand another failure, and that %e would
   be the best thing to use. Unfortunately, other so-called
   POSIX-compliant platforms *don't* implement %e, so it can't be used in
   perl's test suite.

   Paul later listed the remaining issues on Stratus VOS and was happy to
   learn that in some ways VMS is even more restrictive than VOS.

     20 levels!

ext/Time/Piece/Piece.xs use of "strptime"

   In the above process, Paul had a close look at "strptime" used in
   "Time::Piece" and thought it looked suspiciously identical to
   FreeBSD's own implementation, but it lacked the grace to acknowledge
   FreeBSD with a copyright.

   Jerry D. Hedden demanded it be pulled from the core. People explained
   why this was not possible (modules check in, but they never check out)
   and that the module had received Larry Wall's blessing of The Right
   Way to do time manipulations. Other people complained that while the
   module was useful, the name was too cutesy by half.

   Matt Sergeant owned up to being the responsible party, and said he'd
   reinstate the copyright, which probably was chopped in an edit by

     lost in the translation

Syntax proposal for matching balanced strings

   Johan Vromans noted that 5.10 regexp enhancements had made it much
   easier to write regular expressions that match balanced strings, but
   that it would be nice to special-case the easy problems with some
   syntactic sugar.

   Abigail found three flaws in the proposal. David Nicol thought that it
   would be better, on the Teach A Person to Fish principle, to provide a
   good tutorial to help people figure out how to write the expressions

   David then suggested an alternate syntax for matching balanced
   strings, but no code. And I think "\R" already means something

     improved improvement proposal

Show constant in "Useless use of a constant in void context"

   Rick Delaney mentioned that he would like to see exactly which useless
   constant was being used in void context, rather than the current vague
   error message which isn't very helpful. To show he was serious, he
   offered a patch that did just that. Rafael thought the idea was Good
   and applied the patch.

   Hugo van der Sanden listed a number of edge cases where this could
   lead to trouble, but Rafael thought that people who triggered the edge
   cases should probably know why they were triggering them, and Rick

     the error message is the Truth

Change 33302 breaks my Win32 build

   Steve Hay noticed that change #33302 was falling over on Win32, with
   even "miniperl" crashing. The problem was in pp_hot.c, where an
   equality against "cLISTOP->op_last->op_type" was broken, because
   "op_last", while not "NULL", was pointing out the window. Sven
   Dowideit reported similar problems on Solaris.

Change 33313 causing failures

   Jerry D. Hedden reported a new failure in t/op/pat.t that manifested
   itself when run with "TEST", but not in the harness. Much discussion
   followed regarding how the TAP parser deals with garbage.

   The failure in t/op/pat.t was resolved to most people's satisfaction.
   The underlying problem was a typo: "$ = ~/.../" rather than "$ =~
   /.../" and there was a bit of discussion about why that returns the
   complement of 0.

DTrace probes for bleadperl part 2

   Sven Dowideit tried added more DTrace probes to perl, notably to track
   SV allocations, and module loads but was still having trouble with
   getting op.c to cooperate.

Shell patterns are subject to tilde expansion

   Nicholas Clark discovered a latent bug in Configure that would
   manifest itself on a machine without a "csh" C shell installed. He was
   rather surprised to trace the origin of the bug all the way back to
   Perl 1, and defied anyone to find a more ancient bug.

   Given the crappiness of "csh", the true miracle is that no-one
   discovered this bug sooner.

Slowdown of "sort keys %hash" under "use locale"

   Marcus Holland-Moritz noticed that "use locale" prevented a hot C
   routine from being cached during a sort of hash keys, and suggested a
   simple solution, although he was uncertain whether it could break code
   out in the wild.

   Rafael thought the patch looked fine, and suggested that if a bug did
   indeed emerge afterwards, it would probably be due to the magic
   handling code (and so the fix would be made there).

     cache dispenser

Bug or feature in "B::class()"

   Jim Cromie wondered why

     my $start = B::main_start();

   produced a "Can't locate object method" error message. Eirik Berg
   Hanssen explained why and suggested an alternate syntax that would do
   want Jim wanted. Joshua ben Jore said that it was that way because
   no-one had bothered to implement it.

     if you build it

Testing "B"

   Jim Cromie said that a full test suite for the "B" modules would be a
   great idea. In the process of improving "B::Generate", he had begun
   made a good start on doing just that. He posted his current work in
   progress and asked if there was interest in having it in blead.

   Michael G. Schwern made some very good suggestions on how to better
   leverage the testing infrastructure to make Jim's work easier and
   improve the quality of the diagnostics when things break.

     Jimmy B Goode

Assistance with IPC modules and perl 5.10

   Tom Callaway wrote to say that he was preparing perl 5.10 for
   inclusion in the upcoming Fedora 9 release, and was having troubles
   with "IPC::ShareLite" and "IPC::SharedCache". This was holding up the
   process and time was running out, which meant he'd have to go with

   That these two particular modules were deemed to be on the critical
   path puzzled a number of the porters who had either never heard of
   them or had only a vague idea what purpose they served. A careful
   examination of the failures indicated that these two modules were in
   fact optional, and weren't sufficient reason to block the Fedora

   Nevertheless, Tom wanted to know if and how they could be fixed. The
   concensus was that it was a 32/64 bit issue rearing its ugly head.

   Dave Rolsky was of the opinion that these two modules sucked so much
   that no-one in their right mind should be using them.

     memcached, memcached, memcached

Patches of Interest

"PERL_MAGIC_uvar_elem" should be 'u' in dump.c

   Vincent Pit discovered an inconsistency between the magic type
   "uvar_elem" and its symbolic name. He also wondered whether it was
   even used any more. Rafael applied the fix and mentioned that "DBI"
   and/or "Tk" use it.

Is IPC/SysV/SysV.xs compiling?

   Marcus Holland-Moritz wanted to know if Steve Peters and Jarkko
   Hietaniemi were still seeing black smoke compiling this module. If
   not, this would allow him to proceed in the release of a new version.

use svtype

   Robin Barker straightened out the declaration of "sv_type" as an
   "svtype" instead of the current mish-mash of "I32" and "U32" types,
   and added a sprinkle of consting goodness into the mix. Applied by

doio.c "Perl_my_lstat" revisited

   Vincent Pit had a look at the implementation of "my_lstat" and
   discovered that magic was called two times too many and could generate
   a slew of superfluous warnings with "-l undef". He corrected that and
   also fixed a test that was passing when it shouldn't. Steve Peters
   thought the change looked good enough and applied it.

Splitting OP_CONST

   Vincent took Nicholas Clark at his word (from the pp_const, not, that,
   hot thread) and split "OP_CONST" into two separate ops. He had it
   running correctly on both threaded and non-threaded builds, although
   no-one picked it up to apply it to blead.

     what's a semaphore

Updating "Thread::Semaphore" and "Thread::Queue"

   Jerry D. Hedden cast his net wider in the threads infrastructure and
   spent some time working with "Thread::Semaphore". After a couple of
   false starts and doing battle with "Test::More" on 5.8.0, he was able
   to release version 2.04, which Rafael applied to blead.

   Once that was out of the way, Jerry took a look at "Thread::Queue" and
   added some useful functionality and a whole pile of tests.

   Jerry discovered that "Thread::Semaphore" will barf on non-numeric
   parameters, but will happily accept "$sem->up(0.5)" or
   "$sem->down(-1)". Whilst these could be construed as being a semaphore
   that can't make up its mind and a semaphore being raised,
   respectively, Jerry was inclined to classify them as errors as well.

   If no-one voices objections soon, that's probably what such
   shenanigans will become.

Don't install threads files on non-threaded Perls

   H.Merijn Brand thought that all the threads files that were installed
   on a non-threaded build were pretty pointless, untidy and/or a waste
   of space. So Jerry D. Hedden patched the installer to prevent that
   from happening. Rafael Garcia-Suarez applied it, and H.Merijn

   Then he discovered another set of thready files and wondered if they
   could be axed as well.

New and old bugs from RT

More adventures on IRIX (#33849)

   David Cantrell announced that he had warmed up his IRIX iron, and had
   taken the previous suggestions and fixes out for a spin. He reported
   that the compilation had proceeded somewhat further, but still wound
   up crashing and burning.

   Andy Dougherty, unfazed by such minor trivialities, moved onto Plan B,
   which involves using "make minitest", to run a health check on
   "miniperl". He warned that there may many spurious errors due to tests
   relying on modules that have not yet been built but nevertheless may
   provide some clues to what is going wrong.

   Andy's Plan C would be to compile without "-O3" optimisation (his
   initial suspicion being that the C compiler optimiser is getting
   confused). Were David feeling particularly brave, he could pin-point
   the offending file by compiling files with personalised optimisation
   settings, and the resulting knowledge gleaned from the exercise could
   be safely stowed away in the IRIX hints file.

   Nicholas suggested David investigate "ccache" if he was serious about
   trying this last approach.

     the real question is, how many people still use IRIX?

Use of inherited AUTOLOAD for non-method is deprecated (#47047)

   Rick Delaney revived a dead bug that had slipped through the cracks in
   the run-up to 5.10. Steve Peters applied it, and Rafael Garcia-Suarez
   hastily unapplied it, since a minor detail that Rick overlooked in the
   implementation caused segfaults on other platforms.

   Rafael explained that the ultimate correct fix would add a lot of
   make-work code and wasn't sure that the cost was worth it. Rick

"%^H" affecting outside file scopes (#50706)

   Rick Delaney discovered that "%^H" hints could leak across file scopes
   and thought that this wasn't right. He then created a small patch that
   he thought should fix the problem. Rafael believed that Rick was
   right, so he applied it.

"goto" error? (#50742)

   You cannot "goto" a subroutine declaration. This is by design.

Bug fix in malloc.c (#50856)

   Mark Noyes patched the perl memory management helper routine
   "getpages_adjacent" to work around a bug that manifests itself on
   Solaris with 5.6.1 and 5.8.8. No reports as to whether this is
   (still)? a problem in 5.10 or blead.

Perl5 Bug Summary

     287 new + 1498 open = 1785 (Created: 6, Closed: 5)

In Brief

   Paul Marquess thanked Jan Dubois for spotting an omitted change to
   "DB_File". He explained that the impact was purely cosmetic and would
   do something about it the next time something major was scheduled.

   Rafael Garcia-Suarez applied Jerry D. Hedden's read-only variable
   tests from last week.

   Jerry also found an unused variable in perlio.c and Rafael applied
   that as well.

     less bloat

   Jerry then needed help with a "threads::shared" code issue that works
   on blead but warns on maint. Rafael solved it neatly by pointing out
   that the code in question would never be backported to maint since the
   change is technically a change in the API. And thus it could be
   wrapped up in "#ifdef"s.

   Nicholas Clark isolated an interesting self contained task dealing
   with replacing two ops by one op, that would be a nice introduction
   for someone wanting to get their hands dirty working on the internals.

   Philippe Bruhat expressed interest, but then Nicholas spoiled the fun
   by discovering that a one-character patch to solved the
   problem nicely.

     the art is knowing which one character to add

   Robin Barker saw that the last run of "make regen_header" tweaked
   pod/perlapi.pod and posted the changes in a patch. Unapplied.

     why is this not automatic?

   Abigail also thought that her TODO tests for issues relating to "keys
   %+" does not return the correct keys (bug #50496) had been ignored.
   Rafael replied that one of the non-TODO tests was also failing, so he
   TODOified it as well, and applied it all in change #33313.

   Abigail also tweaked perlfunc.pod regarding "%+d" (plus) "sprintf"
   format specifiers. Accepted by Rafael.

   Vincent Pit ran into some "Unbalanced string table refcount" errors on
   a non-threaded blead, that Rafael fixed with change #33322.

     you just have to ask

   Daniel Frederick Crisman wrapped up the no link label on CPAN html
   debate by suggesting that the finer points of POD are best discussed
   on the "pod-people" mailing list.

   Michael Schroeder asked whether Yves had been able to look at
   "0"x51)=~/0{50}/ causing a panic on PPC bug (#50114).

     lost IRL

   In a similar vein, Jan Dubois wondered if his fix for bit-fields for
   VC that would solve bug #50386 had been Warnocked.

   Steve Hat noticed that change #33292 to bitfields caused compiler
   warnings on Win32/VC6. He and Jan discussed the problem, which was
   caused by different types ("int"s and "char"s) being used in
   bit-fields. Steve cleaned everything up with change #33315.

About this summary

     3-10 February 2008

   This summary was written by David Landgren. The in-laws are in town,
   so this week's summary has even less error checking than usual. Please
   forgive me if there are even more typos and wordos than usual.

   Weekly summaries are published on and posted on a
   mailing list, (subscription: The
   archive is at Corrections
   and comments are welcome.

   If you found this summary useful, please consider contributing to the
   Perl Foundation to help support the development of Perl.

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