This Week on perl5-porters - 28 April-3 May 2008
"I've been playing around with MAD this morning [...] The current
state of the tests for MAD is a bit sad, though I hope to have
something that will make interested porters glad in the near future".
-- Jesse Vincent, not a bad lad to spend a tad on MAD. (gad, Dad! it's
not a fad).
Topics of Interest
More on tainting
Nicholas Clark thought that a of points Paul Fenwick made regarding
late-acting taint weren't borne out by an inspection of what the
source code actually did.
Although, looking closely, he found a couple of suspect constructs. He
thought that one possibility was to alter "$^TAINT" to be "undef" if
no tainting, 1 (or true) if -T tainting, or 0 for late-acting
tainting.
Then again, Paul's idea of deprecating late-acting tainting sounded
like the path of least resistance.
better to be safe than sorry
http://xrl.us/bkb8d
Support mallocs of struct T, which contains struct S[N]
Nicholas apologised to Jim Cromie for having not applied his patch,
noting that at the moment Rafael seems to be the only person with
enough motivation to apply patches.
He thought that Jim's avenue of research seemed promising and
suggested he keep slogging on to see whether the rest of it works.
http://xrl.us/bkb8f
Bug in "if(open(my $fh,...))"
In a parallel thread (to bug #53504), Matt Sergeant reopened the
discussion about filehandles persisting past their due date. The
problem arises when one opens a file as a side effect of a conditional
in an if statement.
When Matt learnt that it was sufficient to wrap the "if" block in a
curly block to force the handle to be closed early, he deemed that it
was no longer such a problem.
Hint: if bug reports don't contain the word "perl", they run the risk
of being filed in a "possible spam" folder for human perusal.
it's all right
http://xrl.us/bkb8h
http://xrl.us/bkb8j
5.6.x in the wild
A recent change to the GNU "coreutils" package has broken the
Configure script for 5.6.x (or rather, it's been fixed for more recent
perls for ages, but hasn't been, and is unlikely to be backported to
5.6.x).
Jesse Vincent asked for a show of hands to see how many porters are
still using 5.6, to gauge the importance of creating a fix for
software that was released eight years ago.
Gabor Szabo won a surprisingly crowded race, by having the courage to
admit that he has a client still running perl 4.x in a couple of
places.
an unscientific survey
http://xrl.us/bkb8m
GNU coreutils 6.9 breaks F<Configure> (#53446)
http://xrl.us/bkca2
Prototypes, parsing and optrees
Nicholas Clark thought there was a smidgen of performance to be gained
by figuring out what context a routine needed to used to call a
function and that maybe a prototype, or its absence, could help. But
Rafael explained that what he was looking at was actually from
something completely different, so the question is moot.
http://xrl.us/bkb8o
Weird kernel failure in t/op/threads.t in [EMAIL PROTECTED]
David Landgren related the tale of a test suite falling into an
infinite loop, spewing out the message
Fatal error 'Exceeded maximum lock level' at line 199 in file
/usr/src/lib/libpthread/thread/thr_rtld.c (errno = 136039556)
and wondered if it was the symptom of some recent change. Nicholas
Clark thought that the fact that the test was run on a 6-cpu machine
running FreeBSD 6.0 was probably a better explanation.
Nicholas also thought it would be slightly more helpful if the "-V"
switch were able to report the number of CPUs on the machine, at least
for a subset of platforms where such a test was easy enough to
determine.
Abe Timmerman looked at the code in Test::Smoke::SysInfo and wrote no,
but I think he meant yes. If so, it should just be a simple matter of
programming...
http://xrl.us/bkb8q
http://xrl.us/bkb8s
Smoker segfaults on OpenBSD 4.1
Stephen Schubiger reported that smoke tests of blead had been crashing
with what turned out to be low-level XS problems. Abe Timmerman had
heard of the problem also occurring on FreeBSD 7.0.
In the meantime, Stephen discovered that the latest release of the
smoker's companion (Test::Smoke 1.32) fixed the problem.
smokers of the world, upgrade
http://xrl.us/bkb8u
http://xrl.us/bkb8w
5.8.9-to-be on Irix
David Cantrell reported the results of a smoke for the upcoming 5.8
release on IRIX. Everything was fine except for a couple of failures
in "Sys::Syslog". One issue involved taint, the other was possibly
related to CPAN# 30710, but Sébastien Aperghis-Tramoni had no real
idea about the heart of the problem.
http://xrl.us/bkb8y
http://xrl.us/bkb82
Similarly, the same problem also occurred with blead, although
"Time::Piece" and "Archive::Extract" were also giving grief.
bleeding on Irix
http://xrl.us/bkb84
Parameterize "ptr_table_new(table-size)"
Jim Cromie delivered another fiendishly obscure patch to improve the
performance of ptr_tables, which serve an important role in
implementing hashes. Part of the aim was to expose the guts so that
things like Storable could delve deeper into the core for an increase
in performance.
Nicholas Clark was a bit uncomfortable with the idea, expressing the
wish to see more performance tweaks that don't expand the public API.
Apart from that, he felt that Jim's research might be help re-tune
various magic numbers used for sizing things in the core.
The main sticking point was a useful set of benchmarks to help examine
the result of changes to the core.
http://xrl.us/bkb86
Another perldoc shortcut
It suddenly dawned on Gisle Aas that instead of typing "perldoc
perlintro" one could just as easily type "perldoc intro". He wrote a
patch so that if it failed to find something, it would prepend "perl"
to the search string and try again. Thus "perldoc re" would continue
to return the page on the "re" pragma, rather than the "perlre" page.
all that's lacking is shell auto-completion
http://xrl.us/bkb88
Adriano Ferreira liked the idea so much he pushed "Pod::Perldoc"
version 3.14_06 out to CPAN and asked for feedback.
RFC
http://xrl.us/bkb9a
Upgrading to "Digest::SHA" 5.47
The CPAN version has apparently been moving files around in the
distribution, and this is naughty, since it causes more work when
integrating into blead. Still not sure if it's all tidied up yet.
bumping into things in the night
http://xrl.us/bkb9c
Bug or not? constants warn only once
Nicholas Clark excoriated the list for wasting time on pointless
questions (why is Ruby slow?) rather than answering more mundane
questions which would help things move forward. The issue at hand was
whether constants should warn once, or as many times as necessary.
Both outcomes are doable, and feasible, so we just need to decide what
to do. All he wanted was someone's opinion.
Aristotle Pagaltzis wanted to be sure that whatever was changed
wouldn't make things slower than they are now, expressing the opinion
(yes!) that things had become slower over time (although for the most
part the price was happily paid). He also took the time to rewrite
Nicholas's proposed tests into something he felt was easier to read.
Dave Mitchell was very surprised to learn of 2x slowdowns in the
regexp engine, and thought that if this was true then it was something
that needed fixing.
Aristotle referred him to an article by Ben Tilly.
Ilya's insight
http://perlmonks.org/?node_id=502408
http://xrl.us/bkb9e
MAD Dumper - missing encoding of XML-unsafe literals in "pre"
Jesse Vincent looked at the state of MAD mode in Perl and was dismayed
by the paucity of tests as well as the way it generated XML. Part of
the problem was the fact that the test suite relies on "XML::Parser",
which is a slightly odd state of affairs to have. At least until Dave
Mitchell gets around to writing an XML parser using /bin/sh.
Unfortunately Jesse used 5.10.0 as a basis, and significant changes
have been made in 5.11 and thus the patch could not be applied. Plus
Gerard Goossen had already fixed it. Nevertheless, had it been
applicable, it would have leaked a scalar, although fortunately Rick
Delaney was around to show Jesse how that could have been fixed.
teacher tell me what's my lesson
http://xrl.us/bkb9g
TODO of the week
The yada yada yada operators
Perl 6's Synopsis 3 says:
*The ... operator is the "yada, yada, yada" list operator, which is
used as the body in function prototypes. It complains bitterly (by
calling fail) if it is ever executed. Variant ??? calls warn, and !!!
calls die.*
Those would be nice to add to Perl 5. That could be done without new
ops.
Patches of Interest
weak.t
Alexandr Ciornii offered a patch to allow "Scalar::Util"'s "weaken"
function to be tested correctly both in the CPAN module and in the
perl core.
and strong coffee
http://xrl.us/bkb9i
Testing $/ with in memory files
Bram noticed that bug #44833 had been resolved, but no tests were ever
added to help pin down the issue. There was an issue with the test
being run by "miniperl", which would possibly give it fits, so Bram
tweaked it to be skipped if run by "miniperl".
Rafael applied the patch as it stood, but Ben Morrow thought of a
tweak for additional robustness. Bram adopted the idea, but it was
apparently left unapplied.
http://xrl.us/bkb9k
Extra tests for t/op/tie.t
As a follow-up to the READONLY bug from last week, Bram added a couple
of tests to make sure things stayed sane. After have mulled over the
issue for a while, he returned to it again this week, asking the
porters whether a deeper overhaul was needed concerning these tests.
Warnocked
http://xrl.us/bkb9n
Win32 process ids can have more than 16 bits
Jan Dubois tweaked the Win32 code to return the full 32-bit PID value
on Windows platforms. He also mentioned that "system" behaves slightly
differently on Windows, in that it returns the PID and not the exit
status.
Paul Johnson thought it was high time (since he's been waiting on it
for ten years) to either document the issue properly, or come up with
a better interface.
32 bits ought to be enough for anybody
http://xrl.us/bkb9p
Two less double magic warnings
Vincent Pit wrote a patch to kill a redundant warning in the construct
"binmode $fh, undef"
http://xrl.us/bkb9r
as well as "tie $x, $m" when $m is undefined.
http://xrl.us/bkb9t
Rafael liked these patches so much, he applied them.
Detab and move POD in Pod/Html.pm
In a prelude to major cleanups in "Pod::Html", David Landgren
submitted a patch to cleanse the whitespace of tabs, and a second
patch to push the POD down to the end of the file (hint: this comes in
handy when using "Devel::Cover").
H.Merijn Brand was loathe to apply the patches, since he remembered
Tom Christiansen vehemently opposing the change last time someone
tried to reformat the code for "stylistic" purposes.
to be continued
http://xrl.us/bkb9v
http://xrl.us/bkb9x
David also noticed that the tests for "Pod::Html" relies on being able
to find /bin/diff or /usr/bin/diff and wondered if "is()" from
Test::More wouldn't do just as well.
evil external OS-dependent dependencies
http://xrl.us/bkb9z
"~~" with non-overloaded objects
With a very small dash of C, Vincent Pit tweaked smart matching to
croak on a non-overloaded object. This made Ricardo Signes, who raised
the issue in the first place, very happy.
r e s p e c t (staying out of the living room)
http://xrl.us/bkb93
Add some links to external resources
Shlomi Fish suggested some links to web pages in the documentation,
but qualified his patch with a complex web of licensing details. This
prevented the patch from receiving much serious consideration.
licensed to patch
http://xrl.us/bkb95
New and old bugs from RT
"Pod::HTML" generates incorrect HTML for "=item *" (#19655)
David Landgren went through the open bugs for "Pod::Html" and noticed
that this one has been fixed as recently as in 5.10.0.
resolved
http://xrl.us/bkb97
Bug in "File::Find" on Windows when target dir is bare drive letter and
"no_chdir = 1" (#41555)
Bram wrote a patch to correct the problem, but wondered how one would
go about how one could write a test for the behaviour.
http://xrl.us/bkb99
Infinite recursion related to "die", overloading, "s///" and "\x{...}"
(#41618)
Bram noted that this problem is still around on blead, and was able to
refine the test cases to show what does and what doesn't cause a
segfault.
getting better all the time
http://xrl.us/bkcab
Unicode and case insensitive regex (#41664)
Bram discovered that for some reason the problem goes away if anchors
are used in the pattern match.
http://xrl.us/bkcad
"Carp::croak()" replace user error message by own (#42329)
Bram wrote a patch to make "croak()" croak with a more useful error
when there are no file descriptors available to pull in "Carp::Heavy".
now you know why
http://xrl.us/bkcaf
"Data::Dumper" ignores "^M" in scalars? (#43617)
Bram tried to convince the bug reporter that this was more a problem
of shell interpretation of newlines rather than being the fault of
"Data::Dumper".
http://xrl.us/bkcah
Missing tests for "sprintf %f" with Nan/+Inf/-Inf (#45383)
Bram wrote some patches to pin down the behaviour of "sprintf".
Applied by Rafael Garcia-Suarez.
http://xrl.us/bkcaj
Clarification about @ISA declaration in perlboot.pod (#45733)
Bram saw that the patch attached to this bug report had never been
applied, and asked why. Rafael explained that he never saw it on the
mailing list the first time around.
will it be applied this time around?
http://xrl.us/bkcam
Split function broken on MacOS (#46073)
Bram found another patch that had been overlooked and so Rafael
applied it.
http://xrl.us/bkcao
"perl -x" reports incorrect line number for errors or warnings (#46369)
Anon Sricharoenchai thanked Bram for his followup on how to
resynchronise perl's concept of line numbers when dealing with files
that contain Perl and non-Perl chunks.
or try Inline
http://xrl.us/bkcaq
Clearing magic (or "length($@)>0" for empty $@ if utf8 is in use) (#51370)
Animator had opened this can of worms last week on the clearing of
magic on $@ with an exploration of sorts on how to fix it.
Rafael Garcia-Suarez commented saying that the results looked
reasonable, but of course one could only be sure with a series of new
tests to ensure that nothing had been broken.
So Bram wrote some code and tests and asked for comments. Nicholas
Clark thought that the code Bram had written had the freeing and
clearing of magic the wrong way around. The code also introduced a new
class of macros to deal with the situation; Nicholas felt this added
unnecessary complexity.
Another thing that caught his eye was the fact that one of Bram's
tests induced a "panic: sv_len_utf8 cache 17 real 0". This will need
to be looked into. Bram thought that this was probably a side effect
of the UTF-8 flag not being cleared when it should have been.
So Nicholas did that, and a after thinking about it for a bit thought
that "mg_free" might be to blame. He and Bram kicked the idea around a
bit more and at one point a proposed change might have had the side
effect of allowing $@ to become tie-able. Nicholas thought that this
was a bit sick, but then again, hmmm. There has been talk of promoting
$@ to a first-class object...
http://xrl.us/bkcas
http://xrl.us/bkcau
perl-5.10.0-33733 assertion with JSON::XS-2.2 (#53244)
This is the thread with Marc Lehmann discussing the use of "SvCUR".
The only followup this week was from Sam Vilain, wondering if there
was a problem or not with "sv_upgrade" and whether Marc might not be
too liberal in choosing when to access "SvCUR".
http://xrl.us/bkcaw
Parse problem in "Switch.pm" (#53414)
Don't use it. Even the author says so.
when given a real switch
http://xrl.us/bkcay
A bug with "Readonly::XS" that might be a guts bug (#53482)
A change in the core might have been the cause of the problem. Bram
added some tests to make sure things didn't drift in the future. After
a couple of idle suggestions, Andreas König came through with the
patch that seemed to be the root cause.
http://xrl.us/bkca4
http://xrl.us/bkca6
op/pwent.t should use the DirectoryService on OS X (#53500)
Jan Dubois outlined the approach that he thought should be taken to
fix this bug, admitting that he didn't have the time right now to
pursue the issue.
feel free to jump in
http://xrl.us/bkca8
Some UTF-8 string with CP932 encoding will freeze DOS BOX (#53502)
Chihiro reported that writing a program in a Japanese environment
worked, but if the program had a different name, it would freeze
inside a Windows DOS box. No comments.
might be a ^S
http://xrl.us/bkcba
Bug in "if(open(my $fh,...)) { }" scoping (#53504)
Matt Sergeant was surprised to discover that $fh was not destroyed
until the end of the scope encompassing the "if", rather than at the
end of the "if" block.
In the subsequent exchange, a work-around was suggested, and the
usefulness and hatefulness of lexicals "leaking" across if/elsif/elsif
blocks was debated.
been there since 5.003
http://xrl.us/bkcbc
continued in May
http://xrl.us/bkcbe
Overload and fallback binary or (|) (#53550)
Bram opened a ticket related to bug #53482 which showed the overload
fallback mechanism privileging string context rather than numeric
context, which, in the context of the bug, would have been more
useful.
Rafael explained that binary or ("|") works on both string and
numbers, so it would be hard to discern what was needed in a
systematically correct way. David Nicol speculated on the possibility
of allowing the author of the overloading to give numeric context the
first chance and resolving the overload.
"we travel on the quiet road"
http://xrl.us/bkcbg
Range operator and magic (#53554)
Bram opened another ticket regarding the range operator, wondering why
the interpreter inspects the contents of $x six times in the fragment
"@y = $x .. $x", where $x was a tied variable (and thus if the magic
was being used to piggy-back side effects, the double magic would
throw things out of kilter).
The prompted Dave Nicol to ask if the range "1..$x" was driving a for
loop, what would happen if the $x value was modified in the loop. Bram
thought that it shouldn't be allowed, and promised a TODO test for it.
magic and loss
http://xrl.us/bkcbi
http://xrl.us/bkcbk
Patch for linux LDAP groups (#53560)
David Dick encountered a test failure regarding groups (as in
/etc/group) containing spaces in names. This occurred on a Linux box
using LDAP authentication, and so his expedient fix was to add Linux
to the list of platforms where group names could be expected to
contain spaces.
Rafael applied the patch, but H.Merijn Brand rightfully pointed out
this scenario would play out the same way on many other Unix-like
platforms. In which case, a much more robust solution would be to
determine if LDAP (or in fact any NIS/NSS mechanism, come to think of
it) was in use, and use that as a basis for the test.
wanted: finer discriminant
http://xrl.us/bkcbn
Zero-length regex bug (#53562)
Another victim failed to notice that "//" has special meaning.
That the problem comes up so frequently caused David Nicol to conclude
that the documentation needs a special EMPTY PATTERN section.
only a wafer-thin documentation patch needed
http://xrl.us/bkcbp
http://xrl.us/bkcbr
perl5.10 and blead crash on win32 (#53586)
Dmitry Karasik uncovered a snippet that runs fine on FreeBSD but
crashes on Win32. Then again, it does involve "IO::Handle", SIGPIPE
signals and setting far too many things to "undef".
bad magic
http://xrl.us/bkcbt
Perl5 Bug Summary
All hail Bram, the new Perl5 bug warrior.
288 new + 1472 open = 1760
Created this week: 8
Closed this week: 64
may his wrangling be long and fruitful
http://xrl.us/bkcbv
http://rt.perl.org/rt3/NoAuth/perl5/Overview.html
In Brief
Bram's documentation patch for "perlrun -x" made it in
http://xrl.us/bj2wx
as did Vincent Pit's patch for segmentation fault with array ties (bug
#51636).
http://xrl.us/bkcbx
On the Why is Ruby on Rails so darn slow thread, Alberto Simões
forwarded a message from Leopold Tötsch that gave some Parrot
benchmarks on crunching Mandelbrot sets.
http://xrl.us/bkcbz
John E. Malmberg took a second shot at getting the forked debugger
working on LINUX/UNIX/CYGWIN/VMS.
http://xrl.us/bkcb3
Marc Lehmann read a fascinating paper on heapsort with n log(n) - 0.9n
comparisons which is interesting because it reduces the number of
comparisons that need to be performed, which is useful in a language
where the compares themselves are expensive.
http://xrl.us/bkcb5
perl @ 33444 was still having problems in Cygwin due to db-btree.t,
io_multihomed.t, HiRes.t and op/alarm.t.
http://xrl.us/bkcb7
Jesse Vincent found a teeny tiny typo in "Encode" 2.24's Makefile.PL.
Applied.
http://xrl.us/bkcb9
Last fortnight's summary
This Fortnight on perl5-porters - 13-27 April 2008
http://xrl.us/bkccb
About this summary
This summary was written by David Landgren.
Weekly summaries are published on http://use.perl.org/ and posted on a
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