In perl.git, the branch blead has been updated
<http://perl5.git.perl.org/perl.git/commitdiff/ca31f56c9ea43ef6c05c38da5542fb95a322f2c1?hp=223483699b06992e953eb5468dbc63a71b52fb3e>
- Log -----------------------------------------------------------------
commit ca31f56c9ea43ef6c05c38da5542fb95a322f2c1
Author: James E Keenan <jkee...@cpan.org>
Date: Mon Feb 27 12:24:25 2017 -0500
When and how to use Devel::PatchPerl to repair older builds.
Following recommendation by Matthew Horsfall.
-----------------------------------------------------------------------
Summary of changes:
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 d05a29d6d7..d8d75c1cb0 100644
--- a/pod/perlgit.pod
+++ b/pod/perlgit.pod
@@ -481,6 +481,13 @@ the "first commit where the bug is solved".
C<git help bisect> 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<make> 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<perlhack/Building perl at older commits>.
+
=head2 Topic branches and rewriting history
Individual committers should create topic branches under
diff --git a/pod/perlhack.pod b/pod/perlhack.pod
index 4c645a6c41..a676f46afb 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<make> 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<perl #72414|https://rt.perl.org/Ticket/Display.html?id=72414>.
+Use of F<Porting/bisect.pl> had identified commit
+C<ba77e4cc9d1ceebf472c9c5c18b2377ee47062e6> as the commit in which a bug was
+corrected. To confirm, a P5P developer wanted to configure and build perl at
+commit C<ba77e4c^> (presumably "bad") and then at C<ba77e4c> (presumably
+"good"). Normal configuration and build was attempted:
+
+ $ sh ./Configure -des -Dusedevel
+ $ make test_prep
+
+C<make>, 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<make test_prep> 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 34b1a33b2d..36ad542bb7 100644
--- a/t/porting/known_pod_issues.dat
+++ b/t/porting/known_pod_issues.dat
@@ -348,6 +348,7 @@ 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
--
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