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[PATCH] How to use Devel::PatchPerl to repair older builds #15900

Closed p5pRT closed 7 years ago

p5pRT commented 7 years ago

Migrated from rt.perl.org#130885 (status was 'resolved')

Searchable as RT130885$

p5pRT commented 7 years ago

From @jkeenan

Created by @jkeenan

The patch attached reflects discussion on #p5p today and is documentation-only. The patch discusses when and how someone debugging problems in the core distribution would use CPAN library Devel​::PatchPerl to get perl to build at an old commit.

Thanks to alh for guidance.

Please review.

Perl Info ``` Flags: category=docs severity=wishlist Site configuration information for perl 5.12.5: Configured by jkeenan at Sun Feb 26 21:10:57 EST 2017. Summary of my perl5 (revision 5 version 12 subversion 5) configuration: Platform: osname=linux, osvers=4.4.0-64-generic, archname=x86_64-linux uname='linux zareason 4.4.0-64-generic #85-ubuntu smp mon feb 20 11:50:30 utc 2017 x86_64 x86_64 x86_64 gnulinux ' config_args='-de -Dprefix=/home/jkeenan/perl5/perlbrew/perls/perl-5.12.5 -Aeval:scriptdir=/home/jkeenan/perl5/perlbrew/perls/perl-5.12.5/bin' hint=recommended, useposix=true, d_sigaction=define useithreads=undef, usemultiplicity=undef useperlio=define, d_sfio=undef, uselargefiles=define, usesocks=undef use64bitint=define, use64bitall=define, uselongdouble=undef usemymalloc=n, bincompat5005=undef Compiler: cc='cc', ccflags ='-fno-strict-aliasing -pipe -fstack-protector -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64', optimize='-O2', cppflags='-fno-strict-aliasing -pipe -fstack-protector -I/usr/local/include' ccversion='', gccversion='5.4.0 20160609', 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 /lib/x86_64-linux-gnu /lib/../lib /usr/lib/x86_64-linux-gnu /usr/lib/../lib /lib /usr/lib /lib64 /usr/lib64 libs=-lnsl -ldb -ldl -lm -lcrypt -lutil -lc perllibs=-lnsl -ldl -lm -lcrypt -lutil -lc libc=libc-2.23.so, so=so, useshrplib=false, libperl=libperl.a gnulibc_version='2.23' Dynamic Linking: dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E' cccdlflags='-fPIC', lddlflags='-shared -O2 -L/usr/local/lib -fstack-protector' Locally applied patches: Devel::PatchPerl 1.38 @INC for perl 5.12.5: /home/jkeenan/perl5/perlbrew/perls/perl-5.12.5/lib/site_perl/5.12.5/x86_64-linux /home/jkeenan/perl5/perlbrew/perls/perl-5.12.5/lib/site_perl/5.12.5 /home/jkeenan/perl5/perlbrew/perls/perl-5.12.5/lib/5.12.5/x86_64-linux /home/jkeenan/perl5/perlbrew/perls/perl-5.12.5/lib/5.12.5 . Environment for perl 5.12.5: HOME=/home/jkeenan LANG=en_US.UTF-8 LANGUAGE=en_US LD_LIBRARY_PATH (unset) LOGDIR (unset) PATH=/home/jkeenan/perl5/perlbrew/bin:/home/jkeenan/perl5/perlbrew/perls/perl-5.12.5/bin:/usr/lib/ccache:/usr/local/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin:/home/jkeenan/bin:/home/jkeenan/bin/perl:/home/jkeenan/bin/shell PERLBREW_BASHRC_VERSION=0.78 PERLBREW_HOME=/home/jkeenan/.perlbrew PERLBREW_MANPATH=/home/jkeenan/perl5/perlbrew/perls/perl-5.12.5/man PERLBREW_PATH=/home/jkeenan/perl5/perlbrew/bin:/home/jkeenan/perl5/perlbrew/perls/perl-5.12.5/bin PERLBREW_PERL=perl-5.12.5 PERLBREW_ROOT=/home/jkeenan/perl5/perlbrew PERLBREW_VERSION=0.78 PERL_BADLANG (unset) PERL_WORKDIR=/home/jkeenan/gitwork/perl SHELL=/bin/bash ```
p5pRT commented 7 years ago

From @jkeenan

0001-When-and-how-to-use-Devel-PatchPerl-to-repair-older-.patch ```diff From 07b35b6fe060e658ccb06d46362abdef0e8c8f34 Mon Sep 17 00:00:00 2001 From: James E Keenan Date: Mon, 27 Feb 2017 12:24:25 -0500 Subject: [PATCH] When and how to use Devel::PatchPerl to repair older builds. Following recommendation by Matthew Horsfall. --- pod/perlgit.pod | 7 ++++++ pod/perlhack.pod | 49 ++++++++++++++++++++++++++++++++++++++++++ t/porting/known_pod_issues.dat | 1 + 3 files changed, 57 insertions(+) diff --git a/pod/perlgit.pod b/pod/perlgit.pod index 9d3edcc..12aace2 100644 --- a/pod/perlgit.pod +++ b/pod/perlgit.pod @@ -481,6 +481,13 @@ the "first commit where the bug is solved". C has much more information on how you can tweak your binary searches. +Following bisection you may wish to configure, build and test perl at +commits identified by the bisection process. Sometimes, particularly +with older perls, C may fail during this process. In this case +you may be able to patch the source code at the older commit point. To +do so, please follow the suggestions provided in +L. + =head2 Topic branches and rewriting history Individual committers should create topic branches under diff --git a/pod/perlhack.pod b/pod/perlhack.pod index c8c6b86..7572d83 100644 --- a/pod/perlhack.pod +++ b/pod/perlhack.pod @@ -1041,6 +1041,55 @@ is broken (for example, the utf8 length cache on long utf8 strings). Add a test that will take a fraction of a second normally, and minutes otherwise, causing the test file to time out on failure. +=head2 Building perl at older commits + +In the course of hacking on the Perl core distribution, you may have occasion +to configure, build and test perl at an old commit. Sometimes C will +fail during this process. If that happens, you may be able to salvage the +situation by using the Devel::PatchPerl library from CPAN (not included in the +core) to bring the source code at that commit to a buildable state. + +Here's a real world example, taken from work done to resolve +L. +Use of F had identified commit +C as the commit in which a bug was +corrected. To confirm, a P5P developer wanted to configure and build perl at +commit C (presumably "bad") and then at C (presumably +"good"). Normal configuration and build was attempted: + + $ sh ./Configure -des -Dusedevel + $ make test_prep + +C, however, failed with output (excerpted) like this: + + cc -fstack-protector -L/usr/local/lib -o miniperl \ + gv.o toke.o perly.o pad.o regcomp.o dump.o util.o \ + mg.o reentr.o mro.o hv.o av.o run.o pp_hot.o sv.o \ + pp.o scope.o pp_ctl.o pp_sys.o doop.o doio.o regexec.o \ + utf8.o taint.o deb.o universal.o globals.o perlio.o \ + perlapi.o numeric.o mathoms.o locale.o pp_pack.o pp_sort.o \ + miniperlmain.o opmini.o perlmini.o + pp.o: In function `Perl_pp_pow': + pp.c:(.text+0x2db9): undefined reference to `pow' + ... + collect2: error: ld returned 1 exit status + makefile:348: recipe for target 'miniperl' failed + make: *** [miniperl] Error 1 + +Another P5P contributor recommended installation and use of Devel::PatchPerl +for this situation, first to determine the version of perl at the commit in +question, then to patch the source code at that point to facilitate a build. + + $ perl -MDevel::PatchPerl -e \ + 'print Devel::PatchPerl->determine_version("/path/to/sourcecode"), "\n";' + 5.11.1 + $ perl -MDevel::PatchPerl -e \ + 'Devel::PatchPerl->patch_source("5.11.1", "/path/to/sourcecode");' + +Once the source was patched, C<./Configure> and C were called +and completed successfully, enabling confirmation of the findings in RT +#72414. + =head1 MORE READING FOR GUTS HACKERS To hack on the Perl guts, you'll need to read the following things: diff --git a/t/porting/known_pod_issues.dat b/t/porting/known_pod_issues.dat index 44c13ff..ebe09a9 100644 --- a/t/porting/known_pod_issues.dat +++ b/t/porting/known_pod_issues.dat @@ -343,6 +343,7 @@ pod/perlgit.pod ? Should you be using F<...> or maybe L<...> instead of 1 pod/perlgit.pod Verbatim line length including indents exceeds 79 by 1 pod/perlguts.pod ? Should you be using L<...> instead of 1 pod/perlhack.pod ? Should you be using L<...> instead of 1 +pod/perlhack.pod Verbatim line length including indents exceeds 79 by 2 pod/perlhist.pod Verbatim line length including indents exceeds 79 by 1 pod/perlhpux.pod Verbatim line length including indents exceeds 79 by 1 pod/perlinterp.pod ? Should you be using L<...> instead of 1 -- 2.7.4 ```
p5pRT commented 7 years ago

From @xsawyerx

On 02/27/2017 08​:15 PM\, James E Keenan (via RT) wrote​:

# New Ticket Created by James E Keenan # Please include the string​: [perl #130885] # in the subject line of all future correspondence about this issue. # \<URL​: https://rt-archive.perl.org/perl5/Ticket/Display.html?id=130885 >

This is a bug report for perl from jkeenan@​cpan.org\, generated with the help of perlbug 1.39 running under perl 5.12.5.

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

The patch attached reflects discussion on #p5p today and is documentation-only. The patch discusses when and how someone debugging problems in the core distribution would use CPAN library Devel​::PatchPerl to get perl to build at an old commit.

I like this patch and these kinds of patches. :)

p5pRT commented 7 years ago

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

p5pRT commented 7 years ago

From @wolfsage

On Tue\, Feb 28\, 2017 at 8​:15 AM\, Matthew Horsfall (alh) \wolfsage@&#8203;gmail\.com wrote​:

On Tue\, Feb 28\, 2017 at 4​:42 AM\, Sawyer X \xsawyerx@&#8203;gmail\.com wrote​:

On 02/27/2017 08​:15 PM\, James E Keenan (via RT) wrote​:

The patch attached reflects discussion on #p5p today and is documentation-only. The patch discusses when and how someone debugging problems in the core distribution would use CPAN library Devel​::PatchPerl to get perl to build at an old commit.

I like this patch and these kinds of patches. :)

Agreed! Thanks James\, I wasn't even aware of 'determine_version'!

-- Matthew Horsfall (alh)

p5pRT commented 7 years ago

From @jkeenan

On Tue\, 28 Feb 2017 09​:43​:36 GMT\, xsawyerx@​gmail.com wrote​:

On 02/27/2017 08​:15 PM\, James E Keenan (via RT) wrote​:

# New Ticket Created by James E Keenan # Please include the string​: [perl #130885] # in the subject line of all future correspondence about this issue. # \<URL​: https://rt-archive.perl.org/perl5/Ticket/Display.html?id=130885 >

This is a bug report for perl from jkeenan@​cpan.org\, generated with the help of perlbug 1.39 running under perl 5.12.5.

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

The patch attached reflects discussion on #p5p today and is documentation-only. The patch discusses when and how someone debugging problems in the core distribution would use CPAN library Devel​::PatchPerl to get perl to build at an old commit.

I like this patch and these kinds of patches. :)

Applied to blead in ca31f56c9ea43ef6c05c38da5542fb95a322f2c1. Marking ticket Resolved.

Thank you very much.

-- James E Keenan (jkeenan@​cpan.org)

p5pRT commented 7 years ago

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