This Week on perl5-porters (17-23 July 2006)

This Week on perl5-porters - 17-23 July 2006

   "I'd like "perlcc" to die because it's an attractive nuisance. People
   keep finding this, finding it doesn't work, and posting "how can I
   make this work" posts" -- Joshua ben Jore, out for blood.

Topics of Interest

Is the "-std=c89" switch worth the pain?

   It started when H.Merijn Brand noticed that the recent addition of the
   "gcc" switch ("-std=c89", to ensure conformance with the C89 ISO/ANSI
   standard), caused the Cygwin compiles to develop an interesting smokey
   flavour.

     That's not supposed to happen
     http://xrl.us/prdp

   After he fixed that up, he then noticed that an HP/UX box was also
   appeared to be rather distressed by the same switch. Despite the fact
   that the "gcc" compiler in question was a much more recent edition.

     Uh oh
     http://xrl.us/prdq

   Jarkko Hietaniemi felt H.Merijn's pain, and recast the patch to enable
   the switch only where it was proven beyond reasonable doubt not to
   cause problems. Much the same way that "-ansi -pedantic" cannot be
   used everywhere.

   Nicholas Clark thought that it was safe now and should ever more be
   so, on FreeBSD. Rafael described some of the creepy-crawly things he
   had encountered in his sojourns through "glibc" headers, and concluded
   that Linux should be scratched off the list altogether. Jarkko fumed
   and went to stand in the corner.

   Sadly, at the end of the day, no more remained, save for a footnote
   buried in the depths of "perlhack".

     Good if you can get it
     http://xrl.us/prdr

Thread Exit

   Jerry D. Hedden summarised the ongoing thread about threads, and how
   they should be exited, and how much they should exit. Of note was a
   post from Eric Rybski, who has been using the ithreads model
   intensively over the past couple of years, and injected an interesting
   point of view into the debate. In a nutshell: threads.pm should not
   impose global semantics on how threads operate.

     Last exit to Threadlyn
     http://xrl.us/prds

   Before going too far down the wrong road, Jerry reported on what he
   had come up with, and asked for feedback. Rafael Garcia-Suarez
   appreciated the backwards-compatible aspects.

   Jan Dubois was a bit uneasy about the behaviour of a thread calling
   "die".

     This way out
     http://xrl.us/prdt

   And so it came to pass that Jerry released "threads" version 1.37. As
   a bonus, the reworking of "Perl_ihtread_hook" appears to have fixed
   bug #39839, although Dave Mitchell expressed doubt as to whether the
   race condition that the bug cites has just been pushed out somewhere
   else.

     Waterbeds
     http://xrl.us/prdu

   And some additional thready goodness also for 1.37.

     http://xrl.us/prdv

   In preparing this patch, Jerry encountered what he thought was a bug
   in test.pl under MSWin32. It turned out to be a problem with newlines
   in fragments of "-e" code.

     http://xrl.us/prdw

"perlbug" on Windows

   Steve Hay was puzzled why "perlbug" was not (apparently) working on
   Windows, and traced it down to a Unixism that leads to a two minute
   timeout on Windows. He considered a fix that would work correctly in
   his corporate environment (using the "USERDNSDOMAIN" environment
   variable), but wondered if this was applicable to the world at large.

     Code set free
     http://xrl.us/prdx

"B::" renovation, and the end of the "perlcc" compiler

   Joshua ben Jore produced a patch to overhaul "B::", to drag it kicking
   and screaming into the 21st century (the module, not Joshua,
   although...)

   One of his biggest gripes was with "B::C" and "B::CC", that he would
   rather see them jettisoned out the airlock, along with "perlcc"
   compiler, saying that all "perlcc" really does is fixes bugs (in the
   same way that flypaper fixes flies). Rafael agreed that this was a
   very tempting suggestion.

   Nicholas wondered if the cascade of events would lead to the removal
   of "ext/Byteloader" as well. Joshua put forward the best argument for
   ditching all of it, and that was if anyone had a burning desire to get
   anything along these lines working, their best chance lay in hooking
   up with the Parrot and Pugs teams, because that was the only way they
   would stand a chance of attracting the attention of anyone who might
   be interested in seeing the task achieved. In the meantime, the perl
   tarball would shrink, which is a bit of a bonus.

     At the end of the line
     http://xrl.us/prdy

Using SV as key in hash

   Elizabeth Mattijsen posted this question on Perlmonks but received no
   useful answers, so she came and asked the porters. She wanted to set a
   hash key to the contents of an SV. In theory it would appear that the
   API supports this, however, it doesn't work in practice.
   Unfortunately, the porters didn't appear to have any special insight
   into the matter, either.

     Anyone?
     http://xrl.us/prdz

Patches of Interest

Problem with autogenerated ppport.h files (Change 28513)

   Steve Hay encountered a minor problem due to the changes induced by
   generating ppport.h files on the fly. Marcus Holland-Moritz welcomed
   the information, and whipped up a fix to solve the problems. Steve
   gave it the green light, and Marcus uploaded a new version of
   "Devel::PPPort".

     globby badness
     http://xrl.us/prd2

z/OS: pp_sys.c, reg*.c, toke.c and utf8.c

   Jarkko continued to untangle the useful bits from the z/OS patch that
   the IBM developers posted a while back. He punted on regexec.c, citing
   too many differences in the codebase between then and now, as well as
   philosophical differences.

     http://xrl.us/prd3

New and old bugs from RT

localtime(3) calls tzset(3) but localtime_r(3) may not (#26136)

   Benjamin Holzman delivered another version of the consolidated patch
   to fix this up, but apparently it fell on the floor.

     ping
     http://xrl.us/prd4

Switch module bug (#39789)

   Steve Peters wondered whether it might be able to transmute the
   "Switch" module into the "switch" feature now in "blead". Nicholas
   Clark thought not, citing problems backwards incompatibility, and
   wondered if anybody was particularly interested.

     Not bug-compatible, for a start
     http://xrl.us/prd5

"eval" and hash access in subroutine (#39816)

   Thomas Ziehmer had a problem with a lexical going out of scope in a
   package. David Landgren offered a work-around, using an "our" or
   package variable. Dave Mitchell explained why the behaviour was the
   way it was.

   Rick Delaney took Dave's example and tweaked it to produce a different
   message that seemed to be more in line with the behaviour that Thomas
   had encountered, and after a follow-up from Dave, we all understood
   what was happening.

     Seeking closure
     http://xrl.us/prd6

"PERL5SHELL" is not checked for tainted data (#39832)

   There was a lingering suspicion as to whether $ENV{SystemRoot} and
   $ENV{windir} required taint checks on Win32, but Jan Dubois thought
   that their use was benign as far as Perl was concerned.

     Caring for the environment
     http://xrl.us/o7sg

UTF-8-related crash (#39870)

   "vvv" supplied a small program demonstrating a core dump with UTF-8.
   Andreas Koenig explained that the best way to solve this problem was
   to use "use utf8" instead of "use encoding 'utf8'", whilst cheerfully
   admitting that it was indeed a bug in "use encoding", that continues
   to reside even in a recent version of "blead" (somewhere around patch
   28603).

     Tis a bug
     http://xrl.us/prd7

-0.0 loses signedness upon numeric comparison (#39875)

   Zefram had a problem with -0.0 becoming 0.0 after a numeric
   comparison. Yitzchak Scott-Thoennes proposed an interim fix, but asked
   for a "Configure" probe to check for the existence of a C routine
   ("signbit()") needed to deal with the problem.

   H.Merijn thought that this would mean that the bug would persist on
   platforms that lacked the function, and Yitzchak agreed, and asked
   H.Merijn whether an alternative function ("copysign()") would be
   better. H.Merijn ran some code and produced some statistics of its
   availability.

     http://xrl.us/prd8

"Time::gmtime" 1.02 examples patch (#39876)

   Alexandr Ciornii found some glaring errors in the the documentation to
   "Time::gmtime". Steve Peters applied the fixes, and bumped the version
   up to 1.03.

     About time
     http://xrl.us/prd9

"printf" and "stat" out-of-order (#39880)

   Someone thought they had encountered a problem with "stat", "printf"
   and temporary variables interacting in weird ways, but 'twas merely
   another case of crypto-context.

     Foiled again
     http://xrl.us/prea

Inconsistent list slice behaviour (#39882)

   Bo Lindbergh ran into problems with slices of empty lists, and found
   the different behaviours of "sort", "grep", "do" and company rather
   inconsistent.

     There was probably a reason in the beginning
     http://xrl.us/preb

"ISA" cache leaks into and out of "Safe" compartments (#39887)

   Marc Lehmann discovered, through a quirk in the method caching code,
   that it is possible to have methods names leak into and out of "Safe"
   compartments. He proposed a quick work-around to avoid his specific
   problem, and a tactical nuclear strike to solve the problem in the
   general case, but wondered whether the latter was too heavy-handed. At
   the other end of the spectrum there is the possibility to simply
   document the behaviour and move on.

   Nobody had sufficient motivation to comment one way or the other.

     Safety first
     http://xrl.us/prec

perl 5.8.8: RT 3.6.0: segfault in perl sv.c:5810 (#39893)

   Peter Karl Mueller encountered some MySQL/UTF-8 grief in RT, and asked
   for help.

     http://xrl.us/pred

Docs for "close" don't mention effect of stream error status (#39902)

   Timbo took the time to explain that "close" does The Right Thing, no
   really, but the documentation doesn't clarify that it does, nor what
   it is.

     The path to success
     http://xrl.us/pree

perl C compiler Can't locate object method "IVX" via package "B::NV" 
(#39903)

   Tim Liim reported an error in some code that was compiled with the
   "perlcc" compiler (see also: Topics of Interest this week).

     I'm sorry Tim, I'm afraid I can't do that
     http://xrl.us/pref

Regular expression whitespace character has different meanings in UTF-8 
and single-byte modes (#39912)

   "shadrinovdd" had a problem with character 160, which, when
   interpreted according to ISO Latin-1 rules, is a non-breaking space.
   And this causes different user-visible behaviours to emerge, depending
   on whether the UTF-8 flag is switched on for the string.

   Much discussion ensued as to what the right course of action should
   be.

     Lost in space
     http://xrl.us/preg

Perl5 Bug Summary

     Back below 1500 again
     http://xrl.us/preh

     http://rt.perl.org/rt3/NoAuth/perl5/Overview.html

New Core Modules

   *   "Sys-Syslog" version 0.17 hit the CPAN, thanks to the tireless
       efforts of Sébastien Aperghis-Tramoni.

         http://xrl.us/prei

In Brief

   Jarkko Hietaniemi was all in favour of making "Math::Complex" more
   "bignum"-savvy, but admitted to not knowing how to make it so.

     http://xrl.us/prej

   Steve Hay produced a series of test cases to isolate a "mod_perl" 1.x
   problem using bleadperl. Rafael thought he had the right fix, but that
   didn't work. Dave Mitchell was too busy in the real world to look. The
   problem remains.

     http://xrl.us/o7sx

   Gabor Szabo suggested adding some links to standard modules in
   "perlfunc".

     http://xrl.us/prek

   Jarkko made magic vtables "const" if "PERL_GLOBAL_STRUCT_PRIVATE" is
   defined, perhaps in an attempt to revive the Symbian port.

     http://xrl.us/pren

   Yves Orton had a stab at silencing more warnings when compiling the
   regexp engine, but gnashed his teeth at recalcitrant "printf" format
   strings that refused to play the game.

     http://xrl.us/preo

   Bill Kurland wondered whether the mailing list was the best place to
   ask question regarding regular expression test failures.

     Probably, yes.
     http://xrl.us/prep

   Ashish Agarwal had some trouble with the "Convert-IBM390-0.22" module,
   which was in fact an interesting case study of Unix encountering
   EBCDIC.

     http://xrl.us/preq

   Tim Bunce needed help spotting a leak in the DBI internals. Nicholas
   Clark spotted something that looked fishy. Tim was thrilled, then
   saddened, since afterwards, while the code leaked less, it continued
   to leak a bit.

     The story of my bathroom tap repairs
     http://xrl.us/prer

   Andreas Koenig later reported a problem with "DBI" breaking on
   "blead". Not having a copy handy, Tim asked Andreas to try a one-liner
   fix. After this failed to work, Tim promised to pull down the latest
   "blead" and see what needed to be done.

     After OSCON
     http://xrl.us/pres

   David Nicol put forward a magical vtable proposal. Nicholas Clark said
   that it sounded like a serious undertaking with the possibility that
   the code could be scrapped after much toiling. So he didn't feel like
   doing it.

     http://xrl.us/pret

   Hugo van der Sanden spotted some code in "Net::Cmd" that was
   performing a "last" when it should really have been performing a
   "return", and wondered if anyone agreed with his analysis.

     Silence
     http://xrl.us/preu

   Jarkko taught DEC OSF to use "-g3" if both "-O" and "-g" are
   specified.

     http://xrl.us/prev

About this summary

   This summary was written by David Landgren.

   The p5p summaries will now have a four week recess. I'm off to
   Australia to go traipsing around rain forests, the Barrier Reef and
   Sydney Harbour. With a bit of luck, I won't have to turn a computer on
   at all.

   Writing these summaries has been fun, albeit exhausting at times, and
   I'm looking forward to having a rest for a while. I hope you have
   enjoyed reading them. I'll be back in time for YAPC::EU in Birmingham,
   where I shall try to summarise the the highlights between now and
   then, jet-lagged out of my mind in the back of the auditorium.

   If you want a bookmarklet approach to viewing bugs and change reports,
   there are a couple of bookmarklets that you might find useful on my
   page of Perl stuff:

     http://www.landgren.net/perl/

   Weekly summaries are published on http://use.perl.org/ and posted on a
   mailing list, (subscription: [email protected]). 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 to help support the development of Perl.
-- 
"It's overkill of course, but you can never have too much overkill."