[perl #27028] /$/ not honouring /m in some cases
Zefram
# Please include the string: [perl #27028]
# in the subject line of all future correspondence about this issue.
# <URL: http://rt.perl.org:80/rt3/Ticket/Display.html?id=27028 >
This is a bug report for perl from zef...@fysh.org,
generated with the help of perlbug 1.34 running under perl v5.8.2.
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[Please enter your report here]
Test case #0:
perl -e '$eol = qr/$/m; "foo\nbar\n" =~ /$eol/; print $-[0], "\n"'
Test case #1:
perl -e '$eol = qr/$/m; "foo\nbar\n" =~ /$eol(?:)/; print $-[0], "\n"'
I'm getting the answer 7 from case #0 and 3 from case #1. The correct
answer is 3. (The /$/m pattern should match at the embedded newline at
position 3.)
In case #1, putting anything at all that I've tried into the regexp in
addition to $eol makes it give the correct answer. The semantically
null /(?:)/ is what I'm using as a workaround in the application where
I ran into this. There are other workarounds too.
Putting the /m modifier on where $eol is used also makes it give the right
answer, but for the wrong reason. Here's a related case that misbehaves:
Test case #2:
perl -e '$eol = qr/$/; "foo\nbar\n" =~ /$eol/m; print $-[0], "\n"'
#2 is the converse of #1; it outputs 3 where it should output 7.
The envelope of this bug is quite revealing.
[Please do not change anything below this line]
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---
Flags:
category=core
severity=medium
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Site configuration information for perl v5.8.2:
Configured by Debian Project at Sat Nov 15 18:33:34 EST 2003.
Summary of my perl5 (revision 5.0 version 8 subversion 2) configuration:
Platform:
osname=linux, osvers=2.4.22-xfs+ti1211, archname=i386-linux-thread-multi
uname='linux kosh 2.4.22-xfs+ti1211 #1 sat oct 25 10:11:37 est 2003 i686 gnulinux '
config_args='-Dusethreads -Duselargefiles -Dccflags=-DDEBIAN -Dcccdlflags=-fPIC -Darchname=i386-linux -Dprefix=/usr -Dprivlib=/usr/share/perl/5.8.2 -Darchlib=/usr/lib/perl/5.8.2 -Dvendorprefix=/usr -Dvendorlib=/usr/share/perl5 -Dvendorarch=/usr/lib/perl5 -Dsiteprefix=/usr/local -Dsitelib=/usr/local/share/perl/5.8.2 -Dsitearch=/usr/local/lib/perl/5.8.2 -Dman1dir=/usr/share/man/man1 -Dman3dir=/usr/share/man/man3 -Dsiteman1dir=/usr/local/man/man1 -Dsiteman3dir=/usr/local/man/man3 -Dman1ext=1 -Dman3ext=3perl -Dpager=/usr/bin/sensible-pager -Uafs -Ud_csh -Uusesfio -Uusenm -Duseshrplib -Dlibperl=libperl.so.5.8.2 -Dd_dosuid -des'
hint=recommended, useposix=true, d_sigaction=define
usethreads=define use5005threads=undef useithreads=define usemultiplicity=define
useperlio=define d_sfio=undef uselargefiles=define usesocks=undef
use64bitint=undef use64bitall=undef uselongdouble=undef
usemymalloc=n, bincompat5005=undef
Compiler:
cc='cc', ccflags ='-D_REENTRANT -D_GNU_SOURCE -DTHREADS_HAVE_PIDS -DDEBIAN -fno-strict-aliasing -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64',
optimize='-O3',
cppflags='-D_REENTRANT -D_GNU_SOURCE -DTHREADS_HAVE_PIDS -DDEBIAN -fno-strict-aliasing -I/usr/local/include'
ccversion='', gccversion='3.3.2 (Debian)', gccosandvers=''
intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=1234
d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=12
ivtype='long', ivsize=4, nvtype='double', nvsize=8, Off_t='off_t', lseeksize=8
alignbytes=4, prototype=define
Linker and Libraries:
ld='cc', ldflags =' -L/usr/local/lib'
libpth=/usr/local/lib /lib /usr/lib
libs=-lgdbm -lgdbm_compat -ldb -ldl -lm -lpthread -lc -lcrypt
perllibs=-ldl -lm -lpthread -lc -lcrypt
libc=/lib/libc-2.3.2.so, so=so, useshrplib=true, libperl=libperl.so.5.8.2
gnulibc_version='2.3.2'
Dynamic Linking:
dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-rdynamic'
cccdlflags='-fPIC', lddlflags='-shared -L/usr/local/lib'
Locally applied patches:
---
@INC for perl v5.8.2:
/etc/perl
/usr/local/lib/perl/5.8.2
/usr/local/share/perl/5.8.2
/usr/lib/perl5
/usr/share/perl5
/usr/lib/perl/5.8.2
/usr/share/perl/5.8.2
/usr/local/lib/site_perl
.
---
Environment for perl v5.8.2:
HOME=/home/zefram
LANG (unset)
LANGUAGE (unset)
LD_LIBRARY_PATH (unset)
LOGDIR (unset)
PATH=/home/zefram/pub/i686-pc-linux-gnu/bin:/home/zefram/pub/common/bin:/usr/bin:/usr/X11R6/bin:/bin:/usr/local/bin:/usr/games:/opt/libunsn/bin
PERL_BADLANG (unset)
SHELL=/usr/bin/zsh
h...@crypt.org
:Test case #0:
: perl -e '$eol = qr/$/m; "foo\nbar\n" =~ /$eol/; print $-[0], "\n"'
:
:Test case #1:
: perl -e '$eol = qr/$/m; "foo\nbar\n" =~ /$eol(?:)/; print $-[0], "\n"'
:
:I'm getting the answer 7 from case #0 and 3 from case #1. The correct
:answer is 3. (The /$/m pattern should match at the embedded newline at
:position 3.)
:Test case #2:
: perl -e '$eol = qr/$/; "foo\nbar\n" =~ /$eol/m; print $-[0], "\n"'
:
:#2 is the converse of #1; it outputs 3 where it should output 7.
This is the same bug as #7781, reported way back in October 2001.
For some reason my comments from then aren't attached in RT; you can
find them here:
http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/2001-10/msg00552.html
.. and in the additional followup to that.
I think the right answer for perl-5.10.0 is to remove support for
$* entirely, and fixup the regexp engine to remove references to
PL_multiline and instead use the current flags throughout, and
attach the relevant flags to any cached optimiser substrings for
passing to fbm_instr(). That's likely to be a largish job, and
difficult to make suitable for any maintenance branch.
For maintenance versions it may be possible to identify a reasonable
subset of cases in which the SvTAIL optimisation should be suppressed -
for example, any regexp that mixes +m and -m flag settings. If that is
an avenue worth pursuing, it probably makes sense to develop that in
bleadperl before embarking on the excision of PL_multiline.
As a workaround, you could replace the definition of $eol in your code
with something like qr/(?=\n|\z)/.
Hugo
Rafael Garcia-Suarez
> I think the right answer for perl-5.10.0 is to remove support for
> $* entirely, and fixup the regexp engine to remove references to
> PL_multiline and instead use the current flags throughout, and
> attach the relevant flags to any cached optimiser substrings for
> passing to fbm_instr(). That's likely to be a largish job, and
> difficult to make suitable for any maintenance branch.
$* has already been removed from bleadperl (since before 5.9.0,
actually).