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debugger completely breaks lvalue subs/xs functions #9821

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p5pRT opened this issue Aug 8, 2009 · 4 comments
Closed

debugger completely breaks lvalue subs/xs functions #9821

p5pRT opened this issue Aug 8, 2009 · 4 comments
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distro-Linux type-library

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@p5pRT
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p5pRT commented Aug 8, 2009

Migrated from rt.perl.org#68328 (status was 'resolved')

Searchable as RT68328$
@p5pRT
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p5pRT commented Aug 8, 2009

From perlbug@plan9.de

Created by perlbug@plan9.de

I found that JSON​::XS version 2.24 works differently under the debugger
then without it.

It turns out that this xs function failed to work​:

  SV *incr_text (JSON *self)
  ATTRS​: lvalue
  CODE​:
  ...
  RETVAL = self->incr_text ? SvREFCNT_inc (self->incr_text) : &PL_sv_undef;
  OUTPUT​:
  RETVAL

specifically, this perl statement had no effect​:

  $self->incr_text = "";

This only happened when running under the debugger (perl -d).

This works aorund the issue​:

  CvNODEBUG_on (get_cv ("JSON​::XS​::incr_text", 0)); /* otherwise calling scope can be the debugger */

(shameless feature request​: it would be nice if one could set lvalue and
nodebug on xs, I need this attribute on a lot of functions to work around
debugger bugs).

Apparently the debugger breaks lvalue subs. In fact, the effect is
reproducable easily from within perl​:

  $x = 5;
  sub k : lvalue { $x }
  k = 7;
  die $x;

This prints 5 under the debugger, and 7 without it.

Perl Info 

Flags:
    category=library
    severity=low

Site configuration information for perl 5.10.0:

Configured by Marc Lehmann at Sat Feb 21 02:30:27 CET 2009.

Summary of my perl5 (revision 5 version 10 subversion 0) configuration:
  Platform:
    osname=linux, osvers=2.6.24-etchnhalf.1-amd64, archname=amd64-linux
    uname='linux cerebro 2.6.24-etchnhalf.1-amd64 #1 smp mon jul 21 10:36:02 utc 2008 x86_64 gnulinux '
    config_args='-Duselargefiles -Dxxxxuse64bitint -Uuse64bitall -Dusemymalloc=n -Dcc=gcc -Dccflags=-ggdb -gdwarf-2 -g3 -Dcppflags=-DPERL_ARENA_SIZE=16368 -D_GNU_SOURCE -I/opt/include -Doptimize=-O6 -msse2 -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 -Dxxxusedevel -DxxxDEBUGGING -Dxxxuse_debugging_perl -Dxxxuse_debugmalloc -des'
    hint=recommended, useposix=true, d_sigaction=define
    useithreads=undef, usemultiplicity=undef
    useperlio=define, d_sfio=undef, uselargefiles=define, usesocks=undef
    use64bitint=define, use64bitall=undef, uselongdouble=undef
    usemymalloc=n, bincompat5005=undef
  Compiler:
    cc='gcc', ccflags ='-ggdb -gdwarf-2 -g3 -fno-strict-aliasing -pipe -I/opt/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64',
    optimize='-O6 -msse2 -funroll-loops -fno-strict-aliasing',
    cppflags='-DPERL_ARENA_SIZE=16368 -D_GNU_SOURCE -I/opt/include -ggdb -gdwarf-2 -g3 -fno-strict-aliasing -pipe -I/opt/include'
    ccversion='', gccversion='4.3.2', 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', ldflags ='-L/opt/perl/lib -L/opt/lib -L/usr/local/lib'
    libpth=/usr/local/lib /lib /usr/lib /lib64 /usr/lib64
    libs=-ldl -lm -lcrypt
    perllibs=-ldl -lm -lcrypt
    libc=/lib/libc-2.7.so, so=so, useshrplib=false, libperl=libperl.a
    gnulibc_version='2.7'
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E'
    cccdlflags='-fPIC', lddlflags='-shared -O6 -msse2 -funroll-loops -fno-strict-aliasing -L/opt/perl/lib -L/opt/lib -L/usr/local/lib'

Locally applied patches:
    http://public.activestate.com/cgi-bin/perlbrowse/p/34209
    http://public.activestate.com/cgi-bin/perlbrowse/p/34507
    http://www.gossamer-threads.com/lists/perl/porters/232549
    embed.fnc:Perl_vcroak NULLOK


@INC for perl 5.10.0:
    /root/src/sex
    /opt/perl/lib/perl5
    /opt/perl/lib/perl5
    /opt/perl/lib/perl5
    /opt/perl/lib/perl5
    /opt/perl/lib/perl5
    .


Environment for perl 5.10.0:
    HOME=/root
    LANG (unset)
    LANGUAGE (unset)
    LC_CTYPE=en_US.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:/usr/local/bin:/usr/local/sbin:/root/pserv:.
    PERL5LIB=/root/src/sex
    PERL5_CPANPLUS_CONFIG=/root/.cpanplus/config
    PERLDB_OPTS=ornaments=0
    PERL_ANYEVENT_DBI_TESTS=1
    PERL_ANYEVENT_EDNS0=1
    PERL_ANYEVENT_NET_TESTS=1
    PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6
    PERL_ANYEVENT_STRICT=1
    PERL_BADLANG (unset)
    PERL_UNICODE=0
    SHELL=/bin/bash

@p5pRT
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p5pRT commented Aug 8, 2009

From p5p@perl.wizbit.be

Apparently the debugger breaks lvalue subs. In fact, the effect is
reproducable easily from within perl​:

$x = 5;
sub k : lvalue { $x }
k = 7;
die $x;

This prints 5 under the debugger, and 7 without it.

This should already be fixed in blead with commit​:

http​://perl5.git.perl.org/perl.git/commit/1ad62f649328dc563f7f21be3c384f5adf18af1d

[perl #48489] patch to fix perl bug #7013author bharanee rathna <unknown>
  Tue, 11 Dec 2007 15​:25​:21 +0000 (07​:25 -0800)
committer Steve Peters <steve@​fisharerojo.org>
  Fri, 14 Nov 2008 14​:29​:53 +0000 (14​:29 +0000)
commit 1ad62f6
tree 5c3d6b8a5c665965a82a67619c2a450a4ea89740 tree | snapshot
parent 6fd69bb commit | diff

[perl #48489] patch to fix perl bug #7013
From​: "bharanee rathna" (via RT) <perlbug-followup@​perl.org>
Message-ID​: <rt-3.6.HEAD-28750-1197415521-1978.48489-75-0@​perl.org>

Just the pp_hot.c portion of this patch applied along with removing
the TODO from the test added in the previous change.

p4raw-id​: //depot/perl@​34833

The RT ticket​:
http​://rt.perl.org/rt3//Ticket/Display.html?id=48489
#7013​: lvalue subs not working inside debugger

Best regards,

Bram

@p5pRT
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p5pRT commented Aug 8, 2009

The RT System itself - Status changed from 'new' to 'open'

@p5pRT
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p5pRT commented Aug 8, 2009

p5p@spam.wizbit.be - Status changed from 'open' to 'resolved'

@p5pRT p5pRT closed this as completed Aug 8, 2009
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