This Week on perl5-porters - 17-23 February 2008
Nicholas: So, it seems that constant folding runs in "compile time",
which scares me somewhat. Surely it should be running in run time?
Rafael: The whole point of compile time optimisation is that it runs
at compile time, isn't it?
Nicholas: Runs *at* compile time, but (I assume should) run under run
time rules. There appear to be special exceptions scattered throughout
the code that certain things aren't fatal if compilation is in
progress.
(debating the elegant simplicity of the Perl 5 internals).
Topics of Interest
"pp_const" cools off
Nicholas Clark applied Vincent Pit's patch from last week to slim down
"pp_const" by splitting the op into two, which eliminates a costly
branch.
Sébastien Aperghis-Tramoni reported that his web service that showed
the gcov output of the Perl codebase had gone belly up (it was by
poring over a gcov run that Nicholas spotted the original opportunity
to optimise).
Abe Timmerman said that a similar offering of his own was still up,
except that the perl.gcov target was currently broken, so there was
nothing to show.
paths not taken
http://xrl.us/bgwud
To B or not to B
Jim Cromie and Reini Urban discussed the finer points of testing the
"B" modules.
http://xrl.us/bgwuf
Reini posted some "B::Debug" enhancements.
http://xrl.us/bgwuh
Reini finished up with the delivery the delightfully named "B::MAD"
module. He wasn't sure of the usefulness, but reasoned that some mad
hacker might be able to put it to use.
don't worry B::Happy
http://xrl.us/bgwuj
extending t/test.pl to set the subprocess ENV
Jim Cromie found a simpler way to set up the environment of a test
requiring a fresh perl to be launched. This was to allow
"PERL_XMLDUMP" to be specified, in order to verify MAD output.
Nicholas wondered if Jim's hack was VMS-compatible. Craig A. Berry
suggested that all that was needed was the correct use of "local".
Hilarity ensued as Yitzchak Scott-Thoennes shot down each of Jim's
attempts to effect the change in a loop, which had the result of the
localness (locality?) evaporating at the end of the block.
need a hash slice to go
http://xrl.us/bgwum
Somewhere along the way, Jim noticed a couple of warnings about unused
variables when MAD is enabled.
http://xrl.us/bgwuo
You can't always optimise what you want
Nicholas Clark continued with his interesting self-contained task from
last week that dealt with constant optimisations and thought it should
be possible to unroll constant "pack"s. (like "$var = pack("a2",
"xyz")" being replaced by "$var = "xy""). He had the source code that
could more or less do it, but ran all around the codebase trying to
find a place to lodge it so that it would be acted upon at the right
time. He finally wound up where he started from, and realised that it
wasn't possible.
nor do you always get what you need
http://xrl.us/bgwuq
Assistance with IPC modules and perl 5.10
Nicholas Clark and Andy Armstrong came through with the goods to
figure out what was going wrong with "IPC::Shareable" and
"IPC::ShareLite" on the upcoming Fedora release. So Fedorans will soon
be able use 5.10 straight out of the box.
http://xrl.us/bgwuu
Modulo operator and floating point numbers
Ken Williams considered the recent change to the documentation
concerning the modulo operator and suggested some further tweaks that
Rafael applied.
He then started thinking about moduli of floating point numbers and
was surprised by the results of the current implementation. Zefram
pointed out that the same issue is described in his bug #41215.
Ken would have liked to make things behave in a more logical manner,
but Rafael was happy to let sleeping dogs lie.
http://xrl.us/bgwuw
Perl on Symbian OS
Gowtham wanted to know if the perl port that ran on Symbian 8 was
usable on Symbian 9. Jarkko Hietaniemi, author of the the original
port, was sceptical, given that the platform had been locked down.
This might mean that Perl (as an "unauthorised application") would not
have the privilege of opening a TCP connection.
If the build toolchain has changed significantly then major work will
be required to bring the port up to speed. In any event, Jarkko said
that he had no more time to take care of it.
sounds like no
http://xrl.us/bgwuy
http://xrl.us/bgwu2
"PERL_RUNTIME", or, adventures in "sprintf" ops
Having discovered the nifty f flag and its positive impact on
"length", Nicholas reasoned that "sprintf" was a likely candidate for
more of the same. Except things went wrong, and had him diving all the
way back to Malcolm Beattie's change #44 from 1997. He managed to sort
things out and wrapped it up in change #33369.
http://xrl.us/bgwu4
"use encoding 'utf8'" bug for Latin-1 range
Jarkko Hietaniemi kicked off a long thread last week, and was still
bubbling along nicely as I summarised it. So the executive summary
(subject to change, next week) is that "use encoding" is broken and
its use should be discouraged.
http://xrl.us/bgwu6
UTF-8 problem with Perl 5.10.0
More UTF fun this week. Phil Harvey wrote to explain how he had been
burnt by the changes to "U0" and "C0" flags for "unpack", that used to
allow one to sneak past the abstraction model and poke at the
implementation details. This caused a number of mutually
irreconcilable problems, and so the decision was made during 5.9 to
make a clean break with the past.
it /was/ noted as an Incompatible Change
http://xrl.us/bgwu8
ohloh
Tels discovered ohloh, and its spectacularly out-of-date idea of
activity on the Perl codebase. It was slurping the contents of Sam
Vilain's git repository, and choking on the complex history of the
codebase. This meant that it looked as if development stopped years
ago. Andy Armstrong fixed up the summary info to indicate that Perl 5
is still alive and kicking.
http://xrl.us/bgwva
Patches of Interest
Installing threads files on non-threaded Perls
Michael G. Schwern questioned the desire to exclude threads modules
from being installed on non-threaded builds. His contention being that
if someone uses the module on a non-threaded build, they get a nice,
informative error message as to why things don't work.
If they are removed, then only a basic "module not found in any of
these zillion directories" message is issued instead. Michael was
worried that some people might go to all the effort of trying to
download the threads package from CPAN, only to find out that it
*still* doesn't work, and in fact cannot unless perl itself is
rebuilt.
Jerry D. Hedden saw the logic in this line of reasoning, and reversed
his stance.
helpful errors
http://xrl.us/bgwvc
back they go
http://xrl.us/bgwve
Elsewhere on planet threads, Jerry pushed some more updates out.
threads 1.69
http://xrl.us/bgwvg
threads::shared 1.17
http://xrl.us/bgwvi
Thread::Semaphore 2.07
http://xrl.us/bgwvk
Thread::Queue 2.06
http://xrl.us/bgwvn
"perl -M:Foo -we 1"
Robin Barker related a london.pm discussion (and curiously, the
discussion was about Perl) relating to "perl -M:DProf -we 1" not
generating a warning. So he tweaked the getopty code in perl.c to make
it do so. Jim Cromie thought that the proposed warning, so worded, was
not particularly helpful.
-M doesn't get the colon
http://xrl.us/bgwvp
http://london.pm.org/pipermail/london.pm/Week-of-Mon-20080218/012723.html
Convert Changes file to UTF-8
Brendan O'Dea converted Changes to UTF-8. I don't know what happened
in transit, but the result was a mess by the time the message hit my
inbox.
http://xrl.us/bgwvr
no archlib in otherlibdirs
Reini Urban proposed a change to the various lib paths. Rafael
admitted the current mechanism was a bit ad-hoc and it reminded him
that he needed to work on a 5.12 roadmap.
Andy Dougherty explained how things are supposed to behave currently.
http://xrl.us/bgwvt
NEXT.pm bug within overloaded stringification
Nicholas Clark tried to apply Marcel Grünauer's fix to "NEXT" but
"patch" failed miserably in the attempt. Nicholas blamed Apple's
software.
http://xrl.us/bgwvv
New and old bugs from RT
threads still crashing (#45053)
Jerry D. Hedden discovered that his thread segfaults would occur
regularly on a machine with 4Gb of RAM, but not on another that had
only 1Gb. He wondered if it could be the symptom of some bad
signed/unsigned voodoo.
Tels replied that he was unable to provoke any crashes on his own
machine.
http://xrl.us/bgwvx
QNX Test failures (#49818)
Matt Kraai diagnosed a series of test failures he was having on QNX.
Two could be traced to tests building a ".pbc" file and then trying to
overwrite it after it had been loaded. His brutal fix for that problem
was to delete the file before overwriting it, but suspected there was
a better approach to the problem.
The second series of tests were due to bugs in QNX's "atof". So the
fix here would be to tweak Configure to use Perl's own implementation.
http://xrl.us/bgwvz
bug in regcomp code leading to panic (#50114)
Yves Orton stopped and suggested a couple of source code changes to
try and regretted that he didn't have more time to devote to the
issue. He nevertheless found the time to commit change #33324 that he
hoped would resolve the problem.
Apparently, it did.
In other news, Michael Schroeder (reporter of the bug) asked why
"$r=qr{^bar}; "foo\nbar" =~ /$r/m or die" dies on blead, but not on
5.8. He tracked down where in the regexp engine things had changed (no
mean feat) and wondered what the reasoning was.
Rick Delaney explained that he had made the change to fix a related
matching problem, and had not thought to add a regression test that
would have caught the change that Michael tripped over.
Yves felt that it could be fixed for 5.10.1.
http://xrl.us/bgwv3
modified hints for Darwin x86 64bit (#50946)
Daniel Quinlan supplied a patch to the Darwin hints file to allow a
64-bit perl build. Rafael applied the patch but Nicholas warned that
there may be problems, since the 64-bitness of the build would not be
reflected in machine/architecture pathnames. This could lead to all
sort of mixed-bitness nightmares if different builds coexisted on the
machine. Unless of course Darwin just does the right thing.
http://xrl.us/bgwv5
"pod2man" needs to translate some ASCII characters (#50950)
Mike Ward complained that backticks and dashes were being incorrectly
translated by "Pod::Man".
http://xrl.us/bgwv7
Install Perl-5.8.7 source on Solaris 10 Sparc (#50960)
Elad Dotan reported having trouble building Perl on Solaris, but
provided so little information that diagnosis was difficult. Andy
Dougherty tried, though.
http://xrl.us/bgwv9
Method dispatch breaks with "defined(\&sub)" (#51072)
Dagfinn Ilmari Mannsåker discovered that trying to call "->next::can"
on a package that has not (yet) been defined will cause a segfault.
Rafael wrote a nifty patch to autovivify it as an empty package.
http://xrl.us/bgwwb
Perl5 Bug Summary
288 new + 1499 open = 1787 (6 more, 4 less)
http://xrl.us/bgwwd
http://rt.perl.org/rt3/NoAuth/perl5/Overview.html
This is the BBC
Devel::LeakTrace
Andreas König was surprised to discover that "Devel::LeakTrace"
was broken, and in fact had been so since change #17968 from 2002.
He wasn't sure on which side the fault lay.
http://xrl.us/bgwwf
In Brief
Robin Barker discovered some C files in the test suite that needed
some consting goodness applied.
http://xrl.us/bgwwh
The recent change #33291 had VMS falling off the wall, so John E.
Malmberg and Craig A. Berry put it back together again.
the king's men
http://xrl.us/bgwwj
Reini Urban gave the Cygwin hints a little TLC. Applied.
http://xrl.us/bgwwm
Steve Hay revived the discussion about automated generation on Win32
configuration information, saying that he had improved the situation
with some Makefile trickery, but full automation remained elusive.
bespoke configuration
http://xrl.us/bgwwo
Porting/expand-macros.pl really does indenting now. (Change #33352).
http://xrl.us/bgwwq
Jim Cromie tweaked his recent opcode generator tweaks, shaving a few
more bytes from op.c.
http://xrl.us/bgwws
About this summary
This summary was written by David Landgren.
Last week's is here
This Week on perl5-porters - 10-16 February 2008
http://xrl.us/bgwwu
Weekly summaries are published on http://use.perl.org/ and posted on a
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