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[ID 20000729.004] (??{ ... }) not sucking data correctly?

From:
Jeffrey Friedl
Date:
July 31, 2000 11:13
Subject:
[ID 20000729.004] (??{ ... }) not sucking data correctly?
Message ID:
200007300544.WAA19158@ventrue.yahoo.com

This is a bug report for perl from jfriedl@yahoo-inc.com,
generated with the help of perlbug 1.28 running under perl v5.6.0.


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

I hesitate to submit this as a bug because it seems that a lot would not be
working if this really is a bug in Perl instead of a bug in my
understanding. If the latter, please accept my appologies for wasting your
time.

This program:

    #!/usr/local/bin/perl -w
    use strict;
    use re 'eval';

    $_ = "a(b(c)d)e";

    my $regex;

	$regex = q{
		     \(

		     (?>
			(?> [^()]+ )
		       |
			(??{ $regex })
		      )*

		     \)
		 };

    print "REGEX IS:  $regex\n\n";
    m/$regex/x;

    print "matched [$&]\n";


when run generates:

    REGEX IS:  
		     \(

		     (?>
			(?> [^()]+ )
		       |
			(??{ $regex })
		      )*

		     \)


    Use of uninitialized value in pattern match (m//) at /tmp/foo3 line 24.
    matched [(c)]

I would have expected the matched string would be "(b(c)d)", and that there
would be no uninitialized value (I'd guess that $regex would be the value
that, well, it was when m// first got it.)

When run with re 'debug', it generates:


    jfriedl@fummy> perl /tmp/foo3
    Compiling REx `
		   \(
		  (?:
		     (?> [^()]+ )
		    |
		     (??{ $np })
		   )*
		   \)
		 '
    size 29 first at 1
       1: EXACT <(>(3)
       3: CURLYX {0,32767}(26)
       5:   BRANCH(20)
       6:     SUSPEND(25)
       8:       PLUS(18)
       9:         ANYOF[\0-'*-\377](0)
      18:       SUCCEED(0)
      19:       TAIL(24)
      20:   BRANCH(24)
      21:     LOGICAL[2](22)
      22:     EVAL(25)
      24:   TAIL(25)
      25:   WHILEM[1/1](0)
      26: NOTHING(27)
      27: EXACT <)>(29)
      29: END(0)
    anchored `(' at 0 floating `)' at 1..2147483647 (checking floating) minlen 2 with eval 
    REGEX IS:  
		     \(

		     (?>
			(?> [^()]+ )
		       |
			(??{ $regex })
		      )*

		     \)


    Compiling REx `
		     \(

		     (?>
			(?> [^()]+ )
		       |
			(??{ $regex })
		      )*

		     \)
		 '
    size 32 first at 1
       1: EXACT <(>(3)
       3: CURLYX {0,32767}(29)
       5:   SUSPEND(28)
       7:     BRANCH(22)
       8:       SUSPEND(26)
      10:         PLUS(20)
      11:           ANYOF[\0-'*-\377](0)
      20:         SUCCEED(0)
      21:         TAIL(26)
      22:     BRANCH(26)
      23:       LOGICAL[2](24)
      24:       EVAL(26)
      26:     SUCCEED(0)
      27:     TAIL(28)
      28:   WHILEM[1/1](0)
      29: NOTHING(30)
      30: EXACT <)>(32)
      32: END(0)
    anchored `(' at 0 floating `)' at 1..2147483647 (checking floating) minlen 2 with eval 
    Guessing start of match, REx `
		     \(

		     (?>
			(?> [^()]+ )
		       |
		       ...' against `a(b(c)d)e'...
    Found floating substr `)' at offset 5...
    Found anchored substr `(' at offset 1...
    Guessed: match at offset 1
    Matching REx `
		     \(

		     (?>
			(?> [^()]+ )
		       |
		       ...' against `(b(c)d)e'
      Setting an EVAL scope, savestack=16
       1 <a> <(b(c)d)e>       |  1:  EXACT <(>
       2 <a(> <b(c)d)e>       |  3:  CURLYX {0,32767}
       2 <a(> <b(c)d)e>       | 28:    WHILEM[1/1]
				  0 out of 0..32767  cc=bffff0c4
      Setting an EVAL scope, savestack=21
       2 <a(> <b(c)d)e>       |  5:      SUSPEND
       2 <a(> <b(c)d)e>       |  7:        BRANCH
      Setting an EVAL scope, savestack=21
       2 <a(> <b(c)d)e>       |  8:          SUSPEND
       2 <a(> <b(c)d)e>       | 10:            PLUS
			       ANYOF[\0-'*-\377] can match 1 times out of 32767...
      Setting an EVAL scope, savestack=21
       3 <a(b> <(c)d)e>       | 20:              SUCCEED
					    could match...
       3 <a(b> <(c)d)e>       | 26:          SUCCEED
					could match...
       3 <a(b> <(c)d)e>       | 28:      WHILEM[1/1]
				    1 out of 0..32767  cc=bffff0c4
      Setting an EVAL scope, savestack=26
       3 <a(b> <(c)d)e>       |  5:        SUSPEND
       3 <a(b> <(c)d)e>       |  7:          BRANCH
      Setting an EVAL scope, savestack=26
       3 <a(b> <(c)d)e>       |  8:            SUSPEND
       3 <a(b> <(c)d)e>       | 10:              PLUS
			       ANYOF[\0-'*-\377] can match 0 times out of 32767...
      Setting an EVAL scope, savestack=26
					    failed...
					  failed...
       3 <a(b> <(c)d)e>       | 23:            LOGICAL[2]
       3 <a(b> <(c)d)e>       | 24:            EVAL
      re_eval 0x810c180
    Use of uninitialized value in pattern match (m//) at /tmp/foo3 line 25.
    Compiling REx `'
    size 2 first at 1
       1: NOTHING(2)
       2: END(0)
    minlen 0 
    Entering embedded `'
      Setting an EVAL scope, savestack=31
       3 <a(b> <(c)d)e>       |  1:              NOTHING
       3 <a(b> <(c)d)e>       |  2:              END
      Setting an EVAL scope, savestack=36
       3 <a(b> <(c)d)e>       | 26:                SUCCEED
					      could match...
       3 <a(b> <(c)d)e>       | 28:        WHILEM[1/1]
				      2 out of 0..32767  cc=bffff0c4
				      empty match detected, try continuation...
       3 <a(b> <(c)d)e>       | 29:          NOTHING
       3 <a(b> <(c)d)e>       | 30:          EXACT <)>
					failed...
				      failed...
				    failed, try continuation...
       3 <a(b> <(c)d)e>       | 29:        NOTHING
       3 <a(b> <(c)d)e>       | 30:        EXACT <)>
				      failed...
				    failed...
				  failed, try continuation...
       2 <a(> <b(c)d)e>       | 29:      NOTHING
       2 <a(> <b(c)d)e>       | 30:      EXACT <)>
				    failed...
				  failed...
				failed...
      Setting an EVAL scope, savestack=16
       3 <a(b> <(c)d)e>       |  1:  EXACT <(>
       4 <a(b(> <c)d)e>       |  3:  CURLYX {0,32767}
       4 <a(b(> <c)d)e>       | 28:    WHILEM[1/1]
				  0 out of 0..32767  cc=bffff0c4
      Setting an EVAL scope, savestack=21
       4 <a(b(> <c)d)e>       |  5:      SUSPEND
       4 <a(b(> <c)d)e>       |  7:        BRANCH
      Setting an EVAL scope, savestack=21
       4 <a(b(> <c)d)e>       |  8:          SUSPEND
       4 <a(b(> <c)d)e>       | 10:            PLUS
			       ANYOF[\0-'*-\377] can match 1 times out of 32767...
      Setting an EVAL scope, savestack=21
       5 <a(b(c> <)d)e>       | 20:              SUCCEED
					    could match...
       5 <a(b(c> <)d)e>       | 26:          SUCCEED
					could match...
       5 <a(b(c> <)d)e>       | 28:      WHILEM[1/1]
				    1 out of 0..32767  cc=bffff0c4
      Setting an EVAL scope, savestack=26
       5 <a(b(c> <)d)e>       |  5:        SUSPEND
       5 <a(b(c> <)d)e>       |  7:          BRANCH
      Setting an EVAL scope, savestack=26
       5 <a(b(c> <)d)e>       |  8:            SUSPEND
       5 <a(b(c> <)d)e>       | 10:              PLUS
			       ANYOF[\0-'*-\377] can match 0 times out of 32767...
      Setting an EVAL scope, savestack=26
					    failed...
					  failed...
       5 <a(b(c> <)d)e>       | 23:            LOGICAL[2]
       5 <a(b(c> <)d)e>       | 24:            EVAL
      re_eval 0x810c180
    Entering embedded `'
      Setting an EVAL scope, savestack=31
       5 <a(b(c> <)d)e>       |  1:              NOTHING
       5 <a(b(c> <)d)e>       |  2:              END
      Setting an EVAL scope, savestack=36
       5 <a(b(c> <)d)e>       | 26:                SUCCEED
					      could match...
       5 <a(b(c> <)d)e>       | 28:        WHILEM[1/1]
				      2 out of 0..32767  cc=bffff0c4
				      empty match detected, try continuation...
       5 <a(b(c> <)d)e>       | 29:          NOTHING
       5 <a(b(c> <)d)e>       | 30:          EXACT <)>
       6 <a(b(c)> <d)e>       | 32:          END
    Match successful!
    matched [(c)]
    Freeing REx: `
		     \(

		     (?>
			(?> [^()]+ )
		       |
		       ...'
    Freeing REx: `
		   \(
		  (?:
		     (?> [^()]+ )
		    |
		     (??{ $n...'



[Please do not change anything below this line]
-----------------------------------------------------------------
---
Flags:
    category=core
    severity=medium
---
Site configuration information for perl v5.6.0:

Configured by jfriedl at Sat Jul 29 20:09:33 PDT 2000.

Summary of my perl5 (revision 5.0 version 6 subversion 0) configuration:
  Platform:
    osname=linux, osvers=2.2.15, archname=i686-linux
    uname='linux fummy.dsl.yahoo.com 2.2.16 #6 smp sun jul 23 11:26:16 pdt 2000 i686 unknown '
    config_args='-ds -e -A optimize=-g'
    hint=previous, useposix=true, d_sigaction=define
    usethreads=undef use5005threads=undef useithreads=undef usemultiplicity=undef
    useperlio=undef d_sfio=undef uselargefiles=define 
    use64bitint=undef use64bitall=undef uselongdouble=undef usesocks=undef
  Compiler:
    cc='cc', optimize='-O2 -g', gccversion=pgcc-2.91.66 19990314 (egcs-1.1.2 release)
    cppflags='-fno-strict-aliasing -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64'
    ccflags ='-fno-strict-aliasing -I/usr/local/include -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=12
    ivtype='long', ivsize=4, nvtype='double', nvsize=8, Off_t='off_t', lseeksize=8
    alignbytes=4, usemymalloc=n, prototype=define
  Linker and Libraries:
    ld='cc', ldflags =' -L/usr/local/lib'
    libpth=/usr/local/lib /lib /usr/lib
    libs=-lnsl -lndbm -lgdbm -ldb -ldl -lm -lc -lposix -lcrypt
    libc=/lib/libc-2.1.1.so, so=so, useshrplib=false, libperl=libperl.a
  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 v5.6.0:
    /home/jfriedl/lib/perl
    /home/jfriedl/lib/perl/yahoo
    /usr/local/lib/perl5/5.6.0/i686-linux
    /usr/local/lib/perl5/5.6.0
    /usr/local/lib/perl5/site_perl/5.6.0/i686-linux
    /usr/local/lib/perl5/site_perl/5.6.0
    /usr/local/lib/perl5/site_perl
    .

---
Environment for perl v5.6.0:
    HOME=/home/jfriedl
    LANG (unset)
    LANGUAGE (unset)
    LD_LIBRARY_PATH=/usr/local/pgsql/lib:/home/jfriedl/src/rvplayer5.0
    LOGDIR (unset)
    PATH=/home/jfriedl/bin:/home/jfriedl/common/bin:/usr/local/gcc-2.95.2/bin:.:/usr/local/pgsql/bin:/usr/local/bin:/usr/X11R6/bin:/bin:/usr/bin:/usr/sbin:/sbin:/home/jfriedl/src/rvplayer5.0
    PERLLIB=/home/jfriedl/lib/perl:/home/jfriedl/lib/perl/yahoo
    PERL_BADLANG (unset)
    SHELL=/bin/tcsh




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