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debugger does not stop at postponed breakpoints #15773

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p5pRT opened this issue Dec 16, 2016 · 6 comments
Open

debugger does not stop at postponed breakpoints #15773

p5pRT opened this issue Dec 16, 2016 · 6 comments

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@p5pRT
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@p5pRT p5pRT commented Dec 16, 2016

Migrated from rt.perl.org#130361 (status was 'open')

Searchable as RT130361$

@p5pRT
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@p5pRT p5pRT commented Dec 16, 2016

From jkahrman@mathworks.com

Created by jkahrman@mathworks.com

Debugger does not stop at postponed breakpoints in perl 5.20

Same behavior in perl5.20 from Debian 8 as perl 5.20 built from source. No
customizations to PERL5DB.

http​://www.perlmonks.com/?node_id=1176116

% perl -dwe0

main​::(-e​:1)​: 0
  DB<1> b File​::Temp->new
Subroutine File​::Temp not found.

  DB<2> b postpone File​::Temp​::new
  DB<3> use File​::Temp
  DB<4> x File​::Temp->new
0 File​::Temp=GLOB(0x283db48)
  -> *File​::Temp​::$fh
  FileHandle({*File​::Temp​::$fh}) => fileno(3)

########### UNEXPECTEDLY did not stop at File​::Temp​::new

  DB<5> b postpone File​::Temp​::new
  DB<6> x File​::Temp->new
0 File​::Temp=GLOB(0x216aa78)
  -> *File​::Temp​::$fh
  FileHandle({*File​::Temp​::$fh}) => fileno(3)

########### UNEXPECTEDLY did not stop at File​::Temp​::new

  DB<7> B *
Deleting all breakpoints...
  DB<8> b postpone File​::Temp​::new
  DB<9> x File​::Temp->new
0 File​::Temp=GLOB(0x216abc8)
  -> *File​::Temp​::$fh
  FileHandle({*File​::Temp​::$fh}) => fileno(3)

########### UNEXPECTEDLY did not stop at File​::Temp​::new

  DB<10> b File​::Temp​::new
  DB<11> x File​::Temp->new
File​::Temp​::new(/.../x86_64/perl/perl-5.20.2-mw-014/lib/5.20.2/File/Temp.pm​:885)​:
885​: my $proto = shift;
  DB<<12>> c
0 File​::Temp=GLOB(0x216aeb0)
  -> *File​::Temp​::$fh
  FileHandle({*File​::Temp​::$fh}) => fileno(3)

########### STOPPED at File​::Temp​::new as EXPECTED

Perl Info

Flags:
    category=core
    severity=medium

Site configuration information for perl 5.20.2:

Configured by Debian Project at Mon Jan 11 23:24:04 UTC 2016.

Summary of my perl5 (revision 5 version 20 subversion 2) configuration:

  Platform:
    osname=linux, osvers=3.16.0-4-amd64, archname=x86_64-linux-gnu-thread-multi
    uname='linux themisto 3.16.0-4-amd64 #1 smp debian 3.16.7-ckt20-1+deb8u1 (2015-12-14) x86_64 gnulinux '
    config_args='-Dusethreads -Duselargefiles -Dccflags=-DDEBIAN -D_FORTIFY_SOURCE=2 -g -O2 -fstack-protector-strong -Wformat -Werror=format-security -Dldflags= -Wl,-z,relro -Dlddlflags=-shared -Wl,-z,relro -Dcccdlflags=-fPIC -Darchname=x86_64-linux-gnu -Dprefix=/usr -Dprivlib=/usr/share/perl/5.20 -Darchlib=/usr/lib/x86_64-linux-gnu/perl/5.20 -Dvendorprefix=/usr -Dvendorlib=/usr/share/perl5 -Dvendorarch=/usr/lib/x86_64-linux-gnu/perl5/5.20 -Dsiteprefix=/usr/local -Dsitelib=/usr/local/share/perl/5.20.2 -Dsitearch=/usr/local/lib/x86_64-linux-gnu/perl/5.20.2 -Dman1dir=/usr/share/man/man1 -Dman3dir=/usr/share/man/man3 -Dsiteman1dir=/usr/local/man/man1 -Dsiteman3dir=/usr/local/man/man3 -Duse64bitint -Dman1ext=1 -Dman3ext=3perl -Dpager=/usr/bin/sensible-pager -Uafs -Ud_csh -Ud_ualarm -Uusesfio -Uusenm -Ui_libutil -Uversiononly -DDEBUGGING=-g -Doptimize=-O2 -Duseshrplib -Dlibperl=libperl.so.5.20.2 -des'
    hint=recommended, useposix=true, d_sigaction=define
    useithreads=define, usemultiplicity=define
    use64bitint=define, use64bitall=define, uselongdouble=undef
    usemymalloc=n, bincompat5005=undef
  Compiler:
    cc='cc', ccflags ='-D_REENTRANT -D_GNU_SOURCE -DDEBIAN -fwrapv -fno-strict-aliasing -pipe -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64',
    optimize='-O2 -g',
    cppflags='-D_REENTRANT -D_GNU_SOURCE -DDEBIAN -fwrapv -fno-strict-aliasing -pipe -I/usr/local/include'
    ccversion='', gccversion='4.9.2', 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='cc', ldflags =' -fstack-protector -L/usr/local/lib'
    libpth=/usr/local/lib /usr/lib/gcc/x86_64-linux-gnu/4.9/include-fixed /usr/include/x86_64-linux-gnu /usr/lib /lib/x86_64-linux-gnu /lib/../lib /usr/lib/x86_64-linux-gnu /usr/lib/../lib /lib
    libs=-lgdbm -lgdbm_compat -ldb -ldl -lm -lpthread -lc -lcrypt
    perllibs=-ldl -lm -lpthread -lc -lcrypt
    libc=libc-2.19.so, so=so, useshrplib=true, libperl=libperl.so.5.20
    gnulibc_version='2.19'
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E'
    cccdlflags='-fPIC', lddlflags='-shared -L/usr/local/lib -fstack-protector'

Locally applied patches:
    DEBPKG:debian/cpan_definstalldirs - Provide a sensible INSTALLDIRS default for modules installed from CPAN.
    DEBPKG:debian/db_file_ver - http://bugs.debian.org/340047 Remove overly restrictive DB_File version check.
    DEBPKG:debian/doc_info - Replace generic man(1) instructions with Debian-specific information.
    DEBPKG:debian/enc2xs_inc - http://bugs.debian.org/290336 Tweak enc2xs to follow symlinks and ignore missing @INC directories.
    DEBPKG:debian/errno_ver - http://bugs.debian.org/343351 Remove Errno version check due to upgrade problems with long-running processes.
    DEBPKG:debian/libperl_embed_doc - http://bugs.debian.org/186778 Note that libperl-dev package is required for embedded linking
    DEBPKG:fixes/respect_umask - Respect umask during installation
    DEBPKG:debian/writable_site_dirs - Set umask approproately for site install directories
    DEBPKG:debian/extutils_set_libperl_path - EU:MM: set location of libperl.a under /usr/lib
    DEBPKG:debian/no_packlist_perllocal - Don't install .packlist or perllocal.pod for perl or vendor
    DEBPKG:debian/prefix_changes - Fiddle with *PREFIX and variables written to the makefile
    DEBPKG:debian/fakeroot - Postpone LD_LIBRARY_PATH evaluation to the binary targets.
    DEBPKG:debian/instmodsh_doc - Debian policy doesn't install .packlist files for core or vendor.
    DEBPKG:debian/ld_run_path - Remove standard libs from LD_RUN_PATH as per Debian policy.
    DEBPKG:debian/libnet_config_path - Set location of libnet.cfg to /etc/perl/Net as /usr may not be writable.
    DEBPKG:debian/mod_paths - Tweak @INC ordering for Debian
    DEBPKG:debian/module_build_man_extensions - http://bugs.debian.org/479460 Adjust Module::Build manual page extensions for the Debian Perl policy
    DEBPKG:debian/prune_libs - http://bugs.debian.org/128355 Prune the list of libraries wanted to what we actually need.
    DEBPKG:fixes/net_smtp_docs - [rt.cpan.org #36038] http://bugs.debian.org/100195 Document the Net::SMTP 'Port' option
    DEBPKG:debian/perlivp - http://bugs.debian.org/510895 Make perlivp skip include directories in /usr/local
    DEBPKG:debian/deprecate-with-apt - http://bugs.debian.org/747628 Point users to Debian packages of deprecated core modules
    DEBPKG:debian/squelch-locale-warnings - http://bugs.debian.org/508764 Squelch locale warnings in Debian package maintainer scripts
    DEBPKG:debian/skip-upstream-git-tests - Skip tests specific to the upstream Git repository
    DEBPKG:debian/patchlevel - http://bugs.debian.org/567489 List packaged patches for 5.20.2-3+deb8u3 in patchlevel.h
    DEBPKG:debian/skip-kfreebsd-crash - http://bugs.debian.org/628493 [perl #96272] Skip a crashing test case in t/op/threads.t on GNU/kFreeBSD
    DEBPKG:fixes/document_makemaker_ccflags - http://bugs.debian.org/628522 [rt.cpan.org #68613] Document that CCFLAGS should include $Config{ccflags}
    DEBPKG:debian/find_html2text - http://bugs.debian.org/640479 Configure CPAN::Distribution with correct name of html2text
    DEBPKG:debian/perl5db-x-terminal-emulator.patch - http://bugs.debian.org/668490 Invoke x-terminal-emulator rather than xterm in perl5db.pl
    DEBPKG:debian/cpan-missing-site-dirs - http://bugs.debian.org/688842 Fix CPAN::FirstTime defaults with nonexisting site dirs if a parent is writable
    DEBPKG:fixes/memoize_storable_nstore - [rt.cpan.org #77790] http://bugs.debian.org/587650 Memoize::Storable: respect 'nstore' option not respected
    DEBPKG:debian/regen-skip - Skip a regeneration check in unrelated git repositories
    DEBPKG:fixes/regcomp-mips-optim - [perl #122817] http://bugs.debian.org/754054 Downgrade the optimization of regcomp.c on mips and mipsel due to a gcc-4.9 bug
    DEBPKG:debian/makemaker-pasthru - http://bugs.debian.org/758471 Pass LD settings through to subdirectories
    DEBPKG:fixes/perldoc-less-R - [rt.cpan.org #98636] http://bugs.debian.org/758689 Tell the 'less' pager to allow terminal escape sequences
    DEBPKG:fixes/pod_man_reproducible_date - http://bugs.debian.org/759405 Support POD_MAN_DATE in Pod::Man for the left-hand footer
    DEBPKG:fixes/io_uncompress_gunzip_inmemory - http://bugs.debian.org/747363 [rt.cpan.org #95494] Fix gunzip to in-memory file handle
    DEBPKG:fixes/socket_test_recv_fix - http://bugs.debian.org/758718 [perl #122657] Compare recv return value to peername in socket test
    DEBPKG:fixes/hurd_socket_recv_todo - http://bugs.debian.org/758718 [perl #122657] TODO checking the result of recv() on hurd
    DEBPKG:fixes/regexp-performance - [0fa70a0] http://bugs.debian.org/777556 [perl #123743] simpify and speed up /.*.../ handling
    DEBPKG:fixes/failed_require_diagnostics - http://bugs.debian.org/781120 [perl #123270] Report inaccesible file on failed require
    DEBPKG:fixes/array-cloning - http://bugs.debian.org/779357 [perl #124127] [902d169] fix cloning arrays with unused elements
    DEBPKG:fixes/perldb-threads - http://bugs.debian.org/779357 [perl #124127] [41ef2c6] lib/perl5db.pl: Restore noop lock prototype
    DEBPKG:fixes/CVE-2015-8607_file_spec_taint_fix - ensure File::Spec::canonpath() preserves taint
    DEBPKG:fixes/encode-unicode-bom - http://bugs.debian.org/798727 [rt.cpan.org #107043] Address https://rt.cpan.org/Public/Bug/Display.html?id=107043
    DEBPKG:debian/encode-unicode-bom-doc - http://bugs.debian.org/798727 Document Debian backport of Encode::Unicode fix


@INC for perl 5.20.2:
    /etc/perl
    /usr/local/lib/x86_64-linux-gnu/perl/5.20.2
    /usr/local/share/perl/5.20.2
    /usr/lib/x86_64-linux-gnu/perl5/5.20
    /usr/share/perl5
    /usr/lib/x86_64-linux-gnu/perl/5.20
    /usr/share/perl/5.20
    /usr/local/lib/site_perl
    .


Environment for perl 5.20.2:
    HOME=/home/jkahrman
    LANG=en_US.utf8
    LANGUAGE (unset)
    LD_LIBRARY_PATH=
    LOGDIR (unset)
    PATH=/usr/local/bin:/usr/bin:/bin:/sbin
    PERL_BADLANG (unset)
    SHELL=/usr/local/bin/tcsh

@p5pRT
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@p5pRT p5pRT commented Dec 30, 2016

From @jkeenan

On Fri, 16 Dec 2016 18​:33​:04 GMT, jkahrman@​mathworks.com wrote​:

This is a bug report for perl from jkahrman@​mathworks.com,
generated with the help of perlbug 1.40 running under perl 5.20.2.

-----------------------------------------------------------------
[Please describe your issue here]

Debugger does not stop at postponed breakpoints in perl 5.20

Same behavior in perl5.20 from Debian 8 as perl 5.20 built from
source. No
customizations to PERL5DB.

http​://www.perlmonks.com/?node_id=1176116

% perl -dwe0

main​::(-e​:1)​: 0
DB<1> b File​::Temp->new
Subroutine File​::Temp not found.

DB<2> b postpone File​::Temp​::new
DB<3> use File​::Temp
DB<4> x File​::Temp->new
0 File​::Temp=GLOB(0x283db48)
-> *File​::Temp​::$fh
FileHandle({*File​::Temp​::$fh}) => fileno(3)

########### UNEXPECTEDLY did not stop at File​::Temp​::new

DB<5> b postpone File​::Temp​::new
DB<6> x File​::Temp->new
0 File​::Temp=GLOB(0x216aa78)
-> *File​::Temp​::$fh
FileHandle({*File​::Temp​::$fh}) => fileno(3)

########### UNEXPECTEDLY did not stop at File​::Temp​::new

DB<7> B *
Deleting all breakpoints...
DB<8> b postpone File​::Temp​::new
DB<9> x File​::Temp->new
0 File​::Temp=GLOB(0x216abc8)
-> *File​::Temp​::$fh
FileHandle({*File​::Temp​::$fh}) => fileno(3)

########### UNEXPECTEDLY did not stop at File​::Temp​::new

DB<10> b File​::Temp​::new
DB<11> x File​::Temp->new
File​::Temp​::new(/.../x86_64/perl/perl-5.20.2-mw-
014/lib/5.20.2/File/Temp.pm​:885)​:
885​: my $proto = shift;
DB<<12>> c
0 File​::Temp=GLOB(0x216aeb0)
-> *File​::Temp​::$fh
FileHandle({*File​::Temp​::$fh}) => fileno(3)

########### STOPPED at File​::Temp​::new as EXPECTED

Confirmed that problem exists in 5.24.0 as well.

--
James E Keenan (jkeenan@​cpan.org)

@p5pRT
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@p5pRT p5pRT commented Dec 30, 2016

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

@p5pRT
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@p5pRT p5pRT commented Feb 3, 2017

From jkahrman@mathworks.com

A co-worker had some time to investigate the issue and sent me the following. I haven't yet had time to investigate further.


I think it may need this​:

  --- perl-5.20.2/lib/5.20.2/perl5db.pl 2016-12-01 17​:08​:48.088626441 -0500
  +++ perl5db.pl 2017-01-18 12​:07​:29.552135518 -0500
  @​@​ -6204,6 +6204,7 @​@​

  # Copy the breakpoint in and delete it from %postponed.
  $dbline{$i} = delete $postponed{$subname};
  + _set_breakpoint_enabled_status($file, $i, 1);
  } ## end if ($i)
 
  # find_sub didn't find the sub.

With some printf-style debugging it seems the built-in DB​::postponed() hook (described in perldebguts) is getting hit when the file is compiled, and the area of the code above is attempting to set the breakpoint. But then when DB​::DB() is hit for that line, DB​::_DB__determine_if_we_should_break() says "nope" because _is_breakpoint_enabled($filename, $line) said it was not enabled.

This enabled-ness is implemented in $breakpoints_data{$filename}{$line}{enabled} = $bool. I suspect this is a new thing, and someone forgot to check whether new breakpoints were also being enabled everywhere they are being set.

Which makes me wonder if this problem will show up in other constructs...

@p5pRT
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@p5pRT p5pRT commented Feb 6, 2017

From jkahrman@mathworks.com

After further testing of the postponed feature with the fix and comparing to 5.8.8 behavior, I seem to have made a mistake in my recording of the expected behavior.

While postponed breakpoints ARE broken in (at least) 5.20 and later, I was under the impression that they behaved like regular breakpoints when the file was already loaded. They do not, even in 5.8.8.

So while my first test case IS a regression, my second and third test cases are not.

@p5pRT
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@p5pRT p5pRT commented Feb 6, 2017

From [Unknown Contact. See original ticket]

After further testing of the postponed feature with the fix and comparing to 5.8.8 behavior, I seem to have made a mistake in my recording of the expected behavior.

While postponed breakpoints ARE broken in (at least) 5.20 and later, I was under the impression that they behaved like regular breakpoints when the file was already loaded. They do not, even in 5.8.8.

So while my first test case IS a regression, my second and third test cases are not.

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