another matching finding by pcre author #835

p5pRT · 1999-11-10T05:00:17Z

Migrated from rt.perl.org#1763 (status was 'resolved')

Searchable as RT1763$

p5pRT · 1999-11-10T05:00:17Z

From @jhi

One more from PCRE (ftp://ftp.cus.cam.ac.uk/pub/software/programs/pcre/)
author Philip Hazel. If this (rightly) fails to match

./perl -wle '"a" =~ /^(a)?a$/;print $1'
Use of uninitialized value at -e line 1.

why does this match?

./perl -wle '"a" =~ /^(a)?(?(1)a|b)+$/;print $1'
a

Perl Info



Site configuration information for perl 5.00562:

Configured by jhi at Wed Nov 10 01:04:17 EET 1999.

Summary of my perl5 (revision 5.0 version 5 subversion 62) configuration:
  Platform:
    osname=solaris, osvers=2.7, archname=sun4-solaris
    uname='sunos mimosa.hut.fi 5.7 generic_106541-05 sun4u sparc '
    config_args='-ders -Dcc=gcc'
    hint=recommended, useposix=true, d_sigaction=define
    usethreads=undef useperlio=undef d_sfio=undef
    use64bits=undef usemultiplicity=undef
  Compiler:
    cc='gcc', optimize='-O', gccversion=2.8.1
    cppflags='-DUSE_LARGE_FILES -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64'
    ccflags ='-DUSE_LARGE_FILES -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64'
    stdchar='char', d_stdstdio=define, usevfork=false
    intsize=4, longsize=4, ptrsize=4, doublesize=8
    d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=16
    alignbytes=8, usemymalloc=y, prototype=define
  Linker and Libraries:
    ld='gcc', ldflags =' '
    libpth=/lib /usr/lib /usr/ccs/lib
    libs=-lsocket -lnsl -ldl -lm -lc -lcrypt -lsec
    libc=, so=so, useshrplib=false, libperl=libperl.a
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags=' '
    cccdlflags='-fPIC', lddlflags='-G'

Locally applied patches:
    


@INC for perl 5.00562:
    lib
    /u/vieraat/vieraat/jhi/Perl/lib
    /opt/lib/perl5/5.00562/sun4-solaris
    /opt/lib/perl5/5.00562
    /opt/lib/site_perl/5.00562/sun4-solaris
    /opt/lib/site_perl
    .


Environment for perl 5.00562:
    HOME=/u/vieraat/vieraat/jhi
    LANG=C
    LANGUAGE (unset)
    LC_CTYPE=iso_8859_1
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    PATH=/u/vieraat/vieraat/jhi/.s:/p/bin:/p/adm/bin:/usr/bin:/usr/sbin:/sbin:/bin:/usr/ccs/bin:/usr/lib:/etc:/lib:/p/X6/bin:/usr/bin/X11:/usr/lib/acct:/usr/5bin:/u/vieraat/vieraat/jhi
    PERLLIB=/u/vieraat/vieraat/jhi/Perl/lib
    PERL_BADLANG (unset)
    SHELL=/bin/zsh

p5pRT · 1999-11-10T07:01:58Z

From [Unknown Contact. See original ticket]

In message <199911101300.PAA16873@mimosa.hut.fi>,
Jarkko Hietaniemi writes:

: One more from PCRE (ftp://ftp.cus.cam.ac.uk/pub/software/programs/pcre/)
: author Philip Hazel. If this (rightly) fails to match
:
: ./perl -wle '"a" =~ /^(a)?a$/;print $1'
: Use of uninitialized value at -e line 1.

It does match, but greed makes the ? give up its a, leaving $1 empty:

#! /usr/bin/perl -w

use strict;

print q{"a" =~ /^(a)?a$/}, "\n";
if ("a" =~ /^(a)?a$/) {
print "\$1 = `", defined $1 ? $1 : "<undef>", "'\n";
}
else {
print "No match.\n";
}
[9:05] ruby% ./try
"a" =~ /^(a)?a$/
$1 = `<undef>'

: why does this match?
:
: ./perl -wle '"a" =~ /^(a)?(?(1)a|b)+$/;print $1'
: a

That looks like a bug to me. It should match, but $1 should be empty
in that case.

Greg

p5pRT closed this as completed Nov 28, 2003

p5pRT added Severity Medium distro-Solaris type-library labels Oct 18, 2019

p5pRT mentioned this issue Oct 19, 2019

Program terminated with signal 11, Segmentation fault. #12469

Closed

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another matching finding by pcre author #835

another matching finding by pcre author #835

p5pRT commented Nov 10, 1999

p5pRT commented Nov 10, 1999

p5pRT commented Nov 10, 1999

another matching finding by pcre author #835

another matching finding by pcre author #835

Comments

p5pRT commented Nov 10, 1999

p5pRT commented Nov 10, 1999

From @jhi

p5pRT commented Nov 10, 1999

From [Unknown Contact. See original ticket]