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
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archive is at http://dev.perl.org/perl5/list-summaries/. Corrections
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--
"It's overkill of course, but you can never have too much overkill."
