Out-of-date info on DEBUGGING in perlhacktips, perlrun #15462

p5pRT · 2016-07-19T14:09:28Z

Migrated from rt.perl.org#128670 (status was 'resolved')

Searchable as RT128670$

p5pRT · 2016-07-19T14:09:28Z

From gdg@zplane.com

Created by gdg@zplane.com

Both perlhacktips.pod and perlrun.pod contain some out of date info on
enabling the compiler -DDEBUGGING option during configuration: Both documents
indicate that running ./Configure with -Doptimize=-g will also enable the
compiler -DDEBUGGING option, but this has evidently not been the case for
many years.

Clarification regarding the relationship between the ./Configure
-DDEBUGGING option and the compiler -DDEBUGGING option would also be
helpful for the newbie perl hacker.

More in this thread:

http://www.nntp.perl.org/group/perl.perl5.porters/2016/07/msg238127.html

Perl Info


Flags:
    category=docs
    severity=medium

Site configuration information for perl 5.24.0:

Configured by builduser at Tue May 10 17:41:50 CEST 2016.

Summary of my perl5 (revision 5 version 24 subversion 0) configuration:
   
  Platform:
    osname=linux, osvers=4.5.2-1-arch, archname=i686-linux-thread-multi
    uname='linux flo-32 4.5.2-1-arch #1 smp preempt thu apr 21 18:21:27 cest 2016 i686 gnulinux '
    config_args='-des -Dusethreads -Duseshrplib -Doptimize=-march=i686 -mtune=generic -O2 -pipe -fstack-protector-strong -Dprefix=/usr -Dvendorprefix=/usr -Dprivlib=/usr/share/perl5/core_perl -Darchlib=/usr/lib/perl5/core_perl -Dsitelib=/usr/share/perl5/site_perl -Dsitearch=/usr/lib/perl5/site_perl -Dvendorlib=/usr/share/perl5/vendor_perl -Dvendorarch=/usr/lib/perl5/vendor_perl -Dscriptdir=/usr/bin/core_perl -Dsitescript=/usr/bin/site_perl -Dvendorscript=/usr/bin/vendor_perl -Dinc_version_list=none -Dman1ext=1perl -Dman3ext=3perl -Dlddlflags=-shared -Wl,-O1,--sort-common,--as-needed,-z,relro -Dldflags=-Wl,-O1,--sort-common,--as-needed,-z,relro'
    hint=recommended, useposix=true, d_sigaction=define
    useithreads=define, usemultiplicity=define
    use64bitint=undef, use64bitall=undef, uselongdouble=undef
    usemymalloc=n, bincompat5005=undef
  Compiler:
    cc='cc', ccflags ='-D_REENTRANT -D_GNU_SOURCE -fwrapv -fno-strict-aliasing -pipe -fstack-protector-strong -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64',
    optimize='-march=i686 -mtune=generic -O2 -pipe -fstack-protector-strong',
    cppflags='-D_REENTRANT -D_GNU_SOURCE -fwrapv -fno-strict-aliasing -pipe -fstack-protector-strong -I/usr/local/include'
    ccversion='', gccversion='6.1.1 20160501', gccosandvers=''
    intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=1234, doublekind=3
    d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=12, longdblkind=3
    ivtype='long', ivsize=4, nvtype='double', nvsize=8, Off_t='off_t', lseeksize=8
    alignbytes=4, prototype=define
  Linker and Libraries:
    ld='cc', ldflags ='-Wl,-O1,--sort-common,--as-needed,-z,relro -fstack-protector-strong -L/usr/local/lib'
    libpth=/usr/local/lib /usr/lib/gcc/i686-pc-linux-gnu/6.1.1/include-fixed /usr/lib /lib
    libs=-lpthread -lnsl -lgdbm -ldb -ldl -lm -lcrypt -lutil -lc -lgdbm_compat
    perllibs=-lpthread -lnsl -ldl -lm -lcrypt -lutil -lc
    libc=libc-2.23.so, so=so, useshrplib=true, libperl=libperl.so
    gnulibc_version='2.23'
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E -Wl,-rpath,/usr/lib/perl5/core_perl/CORE'
    cccdlflags='-fPIC', lddlflags='-shared -Wl,-O1,--sort-common,--as-needed,-z,relro -L/usr/local/lib -fstack-protector-strong'



@INC for perl 5.24.0:
    /home/gdg/locperl/lib/perl5/i686-linux-thread-multi
    /home/gdg/locperl/lib/perl5
    /home/gdg/lib/perllib
    /usr/lib/perl5/site_perl
    /usr/share/perl5/site_perl
    /usr/lib/perl5/vendor_perl
    /usr/share/perl5/vendor_perl
    /usr/lib/perl5/core_perl
    /usr/share/perl5/core_perl
    .


Environment for perl 5.24.0:
    HOME=/home/gdg
    LANG=en_US.UTF-8
    LANGUAGE (unset)
    LC_ALL=en_US
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    PATH=/home/gdg/bin:/usr/local/bin:/usr/bin:.:/usr/bin/core_perl:/usr/bin/vendor_perl:/opt/bin32-jre/jre/bin
    PERL5LIB=/home/gdg/locperl/lib/perl5:/home/gdg/lib/perllib
    PERL_BADLANG (unset)
    SHELL=/bin/bash

p5pRT · 2016-07-27T23:53:30Z

From @jkeenan

On Tue Jul 19 07:09:28 2016, gdg@zplane.com wrote:

This is a bug report for perl from gdg@zplane.com,
generated with the help of perlbug 1.40 running under perl 5.24.0.

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

Both perlhacktips.pod and perlrun.pod contain some out of date info on
enabling the compiler -DDEBUGGING option during configuration: Both
documents
indicate that running ./Configure with -Doptimize=-g will also enable
the
compiler -DDEBUGGING option, but this has evidently not been the case
for
many years.

Clarification regarding the relationship between the ./Configure
-DDEBUGGING option and the compiler -DDEBUGGING option would also be
helpful for the newbie perl hacker.

More in this thread:

http://www.nntp.perl.org/group/perl.perl5.porters/2016/07/msg238127.html

Are these the sections of the documentation which you find misleading?

#####
pod/perlhacktips.pod

=head2 Poking at Perl

To really poke around with Perl, you'll probably want to build Perl for
debugging, like this:

./Configure -d -D optimize=-g
make

C<-g> is a flag to the C compiler to have it produce debugging
information which will allow us to step through a running program, and
to see in which C function we are at (without the debugging information
we might see only the numerical addresses of the functions, which is
not very helpful).

F<Configure> will also turn on the C<DEBUGGING> compilation symbol
which enables all the internal debugging code in Perl. There are a
whole bunch of things you can debug with this: L<perlrun> lists them
all, and the best way to find out about them is to play about with
them. The most useful options are probably
#####

#####
pod/perlrun.pod

All these flags require B<-DDEBUGGING> when you compile the Perl
executable (but see C<:opd> in L<Devel::Peek> or L<re/'debug' mode>
which may change this).
See the F<INSTALL> file in the Perl source distribution
for how to do this. This flag is automatically set if you include B<-g>
option when C<Configure> asks you about optimizer/debugger flags.
#####

Thank you very much.

--
James E Keenan (jkeenan@cpan.org)

p5pRT · 2016-07-27T23:53:30Z

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

p5pRT · 2016-07-28T00:13:35Z

From gdg@zplane.com

James E Keenan via RT <perlbug-followup@perl.org> [2016-07-27 16:53:30 -0700]:

On Tue Jul 19 07:09:28 2016, gdg@zplane.com wrote:

This is a bug report for perl from gdg@zplane.com,
generated with the help of perlbug 1.40 running under perl 5.24.0.

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

Both perlhacktips.pod and perlrun.pod contain some out of date info on
enabling the compiler -DDEBUGGING option during configuration: Both
documents
indicate that running ./Configure with -Doptimize=-g will also enable
the
compiler -DDEBUGGING option, but this has evidently not been the case
for
many years.

Clarification regarding the relationship between the ./Configure
-DDEBUGGING option and the compiler -DDEBUGGING option would also be
helpful for the newbie perl hacker.

More in this thread:

http://www.nntp.perl.org/group/perl.perl5.porters/2016/07/msg238127.html

Are these the sections of the documentation which you find misleading?

#####
pod/perlhacktips.pod

=head2 Poking at Perl

To really poke around with Perl, you'll probably want to build Perl for
debugging, like this:
\./Configure \-d \-D optimize=\-g
make
C<-g> is a flag to the C compiler to have it produce debugging
information which will allow us to step through a running program, and
to see in which C function we are at (without the debugging information
we might see only the numerical addresses of the functions, which is
not very helpful).

F<Configure> will also turn on the C<DEBUGGING> compilation symbol
which enables all the internal debugging code in Perl. There are a
whole bunch of things you can debug with this: L<perlrun> lists them
all, and the best way to find out about them is to play about with
them. The most useful options are probably
#####

#####
pod/perlrun.pod

All these flags require B<-DDEBUGGING> when you compile the Perl
executable (but see C<:opd> in L<Devel::Peek> or L<re/'debug' mode>
which may change this).
See the F<INSTALL> file in the Perl source distribution
for how to do this. This flag is automatically set if you include B<-g>
option when C<Configure> asks you about optimizer/debugger flags.
#####

Yes, but mainly the text specifically referring to -g, implying that -g also
turns on the -DDEBUGGING compiler symbol.

Also, it's more than misleading, it's just wrong, at least with modern
perls. At least, that was my experience, and also what I came away with
from reading the responses in the thread where I asked about it. From
those responses, it sounded like Configure -g used to behave the way
that's described in the excerpted text above, but hasn't for quite some time.

p5pRT · 2016-08-08T11:45:10Z

From @iabyn

On Wed, Jul 27, 2016 at 06:13:01PM -0600, Glenn Golden wrote:

Yes, but mainly the text specifically referring to -g, implying that -g also
turns on the -DDEBUGGING compiler symbol.

Also, it's more than misleading, it's just wrong, at least with modern
perls. At least, that was my experience, and also what I came away with
from reading the responses in the thread where I asked about it. From
those responses, it sounded like Configure -g used to behave the way
that's described in the excerpted text above, but hasn't for quite some time.

With commit v5.25.3-166-gf075db8, I've reworked the text in INSTALL,
perlhacktips and perlrun to hopefully make things clearer.

--
All wight. I will give you one more chance. This time, I want to hear
no Wubens. No Weginalds. No Wudolf the wed-nosed weindeers.
-- Life of Brian

p5pRT · 2016-08-08T11:46:21Z

@iabyn - Status changed from 'open' to 'resolved'

p5pRT · 2016-08-08T11:58:46Z

From gdg@zplane.com

Dave Mitchell <davem@iabyn.com> [2016-08-08 12:44:10 +0100]:

On Wed, Jul 27, 2016 at 06:13:01PM -0600, Glenn Golden wrote:

Yes, but mainly the text specifically referring to -g, implying that -g also
turns on the -DDEBUGGING compiler symbol.

Also, it's more than misleading, it's just wrong, at least with modern
perls. At least, that was my experience, and also what I came away with
from reading the responses in the thread where I asked about it. From
those responses, it sounded like Configure -g used to behave the way
that's described in the excerpted text above, but hasn't for quite some time.

With commit v5.25.3-166-gf075db8, I've reworked the text in INSTALL,
perlhacktips and perlrun to hopefully make things clearer.

Thanks Dave! Much improved.

p5pRT closed this as completed Aug 8, 2016

p5pRT added Severity Medium distro-Linux documentation labels Oct 19, 2019

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Out-of-date info on DEBUGGING in perlhacktips, perlrun #15462

Out-of-date info on DEBUGGING in perlhacktips, perlrun #15462

p5pRT commented Jul 19, 2016

p5pRT commented Jul 19, 2016

p5pRT commented Jul 27, 2016

p5pRT commented Jul 27, 2016

p5pRT commented Jul 28, 2016

p5pRT commented Aug 8, 2016

p5pRT commented Aug 8, 2016

p5pRT commented Aug 8, 2016

Out-of-date info on DEBUGGING in perlhacktips, perlrun #15462

Out-of-date info on DEBUGGING in perlhacktips, perlrun #15462

Comments

p5pRT commented Jul 19, 2016

p5pRT commented Jul 19, 2016

From gdg@zplane.com

Created by gdg@zplane.com

p5pRT commented Jul 27, 2016

From @jkeenan

p5pRT commented Jul 27, 2016

p5pRT commented Jul 28, 2016

From gdg@zplane.com

p5pRT commented Aug 8, 2016

From @iabyn

p5pRT commented Aug 8, 2016

p5pRT commented Aug 8, 2016

From gdg@zplane.com