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[perl #33908] $ behaves inconsistent with \G

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From:
Marc Lehmann
Date:
January 24, 2005 03:32
Subject:
[perl #33908] $ behaves inconsistent with \G
Message ID:
rt-3.0.11-33908-106345.5.89234969713097@perl.org
# New Ticket Created by  Marc Lehmann 
# Please include the string:  [perl #33908]
# in the subject line of all future correspondence about this issue. 
# <URL: https://rt.perl.org/rt3/Ticket/Display.html?id=33908 >



This is a bug report for perl from pcg@goof.com,
generated with the help of perlbug 1.35 running under perl v5.8.6.


-----------------------------------------------------------------
[Please enter your report here]

While writing a parse, I found that /\G.*/ sometimes doesn't match, which
I think it should do always, regardless of the content and history of $_.

It turned out that this match, run before, triggers this:

   /\G$/gc;

After that, \G will no longer match.

I think this is a bug becaise the following two segments behave differently:

   $_ = "test";
   /.*$/gc or die "-";       # this line differs
   /\G$/gc or die "A";
   /\G/gc or die "B";

The above dies at "B", while this:

   $_ = "test";
   /$/gc or die "-";         # this line differs
   /\G$/gc or die "A";
   /\G/gc or die "B";

Dies at "A", so the "$" in the first match has different behaviour
depending on wether there is a .* or not in front of it. I think it should
behave the same in both cases. More specifically, I would prefer it to
not die ever (I am not sure how to write my parser if I cannot check for
end-of-string more than once), but one could argue that "$" eats the
physical or virtual line-end.

(The actual problem is that, when implementing the posix shell grammar,
"$" is being treated both as end-of-command and end-of-input, at different
places in my recursive descent parser.  As /\G$/ doesn't match the second
time, the parser assumes a parse error because something is following).

[Please do not change anything below this line]
-----------------------------------------------------------------
---
Flags:
    category=core
    severity=low
---
Site configuration information for perl v5.8.6:

Configured by Marc Lehmann at Tue Nov 30 00:54:44 CET 2004.

Summary of my perl5 (revision 5 version 8 subversion 6) configuration:
  Platform:
    osname=linux, osvers=2.6.10-rc1, archname=amd64-linux
    uname='linux cerebro 2.6.10-rc1 #1 smp mon nov 22 05:47:21 cet 2004 x86_64 gnulinux '
    config_args='-Duselargefiles -Dxuse64bitint -Uxuse64bitall -Dusemymalloc=y -Dcc=gcc-3.4 -Dccflags=-ggdb -Dcppflags=-D_GNU_SOURCE -I/opt/include -Doptimize=-O4 -march=opteron -mtune=opteron -funroll-loops -fno-strict-aliasing -Dcccdlflags=-fPIC -Dldflags=-L/opt/perl/lib -L/opt/lib -Dlibs=-ldl -lm -lcrypt -Darchname=amd64-linux -Dprefix=/opt/perl -Dprivlib=/opt/perl/lib/perl5 -Darchlib=/opt/perl/lib/perl5 -Dvendorprefix=/opt/perl -Dvendorlib=/opt/perl/lib/perl5 -Dvendorarch=/opt/perl/lib/perl5 -Dsiteprefix=/opt/perl -Dsitelib=/opt/perl/lib/perl5 -Dsitearch=/opt/perl/lib/perl5 -Dsitebin=/opt/perl/bin -Dman1dir=/opt/perl/man/man1 -Dman3dir=/opt/perl/man/man3 -Dsiteman1dir=/opt/perl/man/man1 -Dsiteman3dir=/opt/perl/man/man3 -Dman1ext=1 -Dman3ext=3 -Dpager=/usr/bin/less -Uafs -Uusesfio -Uusenm -Uuseshrplib -Dd_dosuid -Dusethreads=undef -Duse5005threads=undef -Duseithreads=undef -Dusemultiplicity=undef -Demail=perl-binary@plan9.de -Dcf_email=perl-binary@plan9.de -Dcf_by=Marc Lehmann -Dlocincpth=/opt/perl/include /opt/include -Dmyhostname=localhost -Dmultiarch=undef -Dbin=/opt/perl/bin -des'
    hint=recommended, useposix=true, d_sigaction=define
    usethreads=undef use5005threads=undef useithreads=undef usemultiplicity=undef
    useperlio=define d_sfio=undef uselargefiles=define usesocks=undef
    use64bitint=define use64bitall=define uselongdouble=undef
    usemymalloc=y, bincompat5005=undef
  Compiler:
    cc='gcc-3.4', ccflags ='-ggdb -fno-strict-aliasing -pipe -I/opt/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64',
    optimize='-O4 -march=opteron -mtune=opteron -funroll-loops -fno-strict-aliasing',
    cppflags='-D_GNU_SOURCE -I/opt/include -ggdb -fno-strict-aliasing -pipe -I/opt/include'
    ccversion='', gccversion='3.4.2 (Debian 3.4.2-3)', gccosandvers=''
    intsize=4, longsize=8, ptrsize=8, doublesize=8, byteorder=12345678
    d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=16
    ivtype='long', ivsize=8, nvtype='double', nvsize=8, Off_t='off_t', lseeksize=8
    alignbytes=8, prototype=define
  Linker and Libraries:
    ld='gcc-3.4', ldflags ='-L/opt/perl/lib -L/opt/lib -L/usr/local/lib'
    libpth=/usr/local/lib /lib /usr/lib
    libs=-ldl -lm -lcrypt
    perllibs=-ldl -lm -lcrypt
    libc=/lib/libc-2.3.2.so, so=so, useshrplib=false, libperl=libperl.a
    gnulibc_version='2.3.2'
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E'
    cccdlflags='-fPIC', lddlflags='-shared -L/opt/perl/lib -L/opt/lib -L/usr/local/lib'

Locally applied patches:
    

---
@INC for perl v5.8.6:
    /root/src/sex
    /opt/perl/lib/perl5
    /opt/perl/lib/perl5
    /opt/perl/lib/perl5
    /opt/perl/lib/perl5
    /opt/perl/lib/perl5
    /opt/perl/lib/perl5
    /opt/perl/lib/perl5
    .

---
Environment for perl v5.8.6:
    HOME=/root
    LANG (unset)
    LANGUAGE (unset)
    LC_CTYPE=de_DE.UTF-8
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    PATH=/root/s2:/root/s:/opt/bin:/opt/sbin:/bin:/sbin:/usr/bin:/usr/sbin:/usr/X11/bin:/usr/games:/root/src/uunet:.
    PERL5LIB=/root/src/sex
    PERL5_CPANPLUS_CONFIG=/root/.cpanplus/config
    PERLDB_OPTS=ornaments=0
    PERL_BADLANG (unset)
    PERL_UNICODE=SAL
    SHELL=/bin/bash


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