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[perl #27028] /$/ not honouring /m in some cases

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From:
Zefram
Date:
February 23, 2004 19:10
Subject:
[perl #27028] /$/ not honouring /m in some cases
Message ID:
rt-3.0.8-27028-79227.10.9485947752979@perl.org
# New Ticket Created by  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 zefram@fysh.org,
generated with the help of perlbug 1.34 running under perl v5.8.2.


-----------------------------------------------------------------
[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]
-----------------------------------------------------------------
---
Flags:
    category=core
    severity=medium
---
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

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